installing 220V outlet for air compressor
Michael Shaffer
questions.
1) The instructions say to wire it straight to the fuse box (no outlet).
Should I really do it this way or would it be ok to install an outlet
in my garage? I would prefer that since it would be easier to unplug it
if I have to move it for some reason.
2) I know I need 10 guage wire but is there any special kind? (Grade, etc..)
3) Should 30 amp breaker be good since the compressor uses 15 amps??
Thanks
BTW here's the compressor
-----------------------------------------------------------------------
http://www.sears.com/data/product_images/tools/large/00918419000-dlv.jpg
Craftsman 60 gal. Air Compressor, 7 hp, Vertical Tank, Oillube Pump
Air compressor features 150 psi and motor has thermal overload
protection. Has a 2 cyclinder oillube pump and provides large air
storage space in a minimum amount or air space with its 60 gal. tank.
Can have heavy-duty use of most air tools and is made of durable
construction with lower oil consumption for longer pump life. It has an
improved dissipation of heat for better filtration and a globe valve
included. It also has an automotive type paper filter that is for better
filtration.
$449
Matt W.
wrote:
> 1) The instructions say to wire it straight to the fuse box (no outlet).
There is no reason that I can see why you can't connect a compressor to an
outlet. You can bet your bippy that's what I would do.
> 2) I know I need 10 guage wire but is there any special kind? (Grade,
> etc..)
How do you know you need 10 gauge wire if you don't know what size breaker
you are using yet? Breakers are sized to protect the wire. If you use a
30amp breaker, you will need 10 gauge wire. If you use a 20amp breaker, you
could use 12 gauge. 15amp breaker would let you use 14 gauge. That said, I
would go ahead with some #10 stranded THHN copper and a 30amp breaker.
> 3) Should 30 amp breaker be good since the compressor uses 15 amps??
Sounds goodm that's what I'd do. But you could get a 20 amp breaker and use
12 gauge.
--
Matt W.
Sent Using M2, Opera's revolutionary e-mail client
http://www.opera.com/m2/
jobel
1: How far from the breaker box it the compressor? That Is how much
wire will it take to make the run between the breaker box and the
compressor?
2; What is the HP of your compressor?
From what you have said in your post an out let should be no problem
and if the run is under 30 feet # 12 - 2 with ground wire is more
than adaquite.. My compressor is 5HP and I run it almost 40 ft on #12
wire no problem. In fact when I wired my shop I wired 229 through out
making every other outlet off a different leg. This serves two purpose
on is to balance the load if I am running more than one machine the
other is to have 220 available any where that I might need it in the
future, My compressor is at the end of this run all on a 30 amp
breaker and #12 wire. Never thrown a breaker. I use a 20 amp plug to
plug my compressor into the line. If you had several 100 feet of wire
between your breaker box and the compressor I might think you would
need #10. In my last shop I had about a 100 ft run to make from the
maine breaker to the sub panel in the shop and I ran #8 into the whole
shop including a 5 HP compressor and a 5500 watt electric heater in
the winter and a 2 1/2 ton air conditioner in the summer.
John Lehman
On Sun, 09 Mar 2003 01:13:06 GMT, Michael Shaffer
<michael...@cox.net> wrote:
Wade
> wire no problem. In fact when I wired my shop I wired 229 through out
> making every other outlet off a different leg. This serves two purpose
> on is to balance the load if I am running more than one machine the
> other is to have 220 available any where that I might need it in the
> future, My compressor is at the end of this run all on a 30 amp
> breaker and #12 wire. Never thrown a breaker. I use a 20
Its a good thing you have never "thrown" a breaker because the inadequate
wire could overheat before you did.
Or is 30a of 229 okay on #12 wire?
Please be more careful with your advice.
Jim P.
Jim P.
"jobel" <jo...@pldi.net> wrote in message
news:jm6l6vco5lthdqk6d...@4ax.com...
Matt W.
> Need to ask a couple of questions.
> 1: How far from the breaker box it the compressor? That Is how much
> wire will it take to make the run between the breaker box and the
> compressor?
> 2; What is the HP of your compressor?
What do either of these Q's have to do with wire and breaker size??? Mike
said his compressor uses 15 amps. That's probably running load, therefore
he should never "throw" a 20 amp breaker, but may be well served to use a
30amp for future upsizing.
> In fact when I wired my shop I wired 229 through out
> making every other outlet off a different leg.
Since 220 uses BOTH legs of your service, how can you run each outlet "off
a different leg"???
> My compressor is at the end of this run all on a 30 amp
> breaker and #12 wire. Never thrown a breaker.
You won't likely "throw" a 30 amp breaker, you're more likely to melt your
wire and/or start a fire. People who don't know what they are doing are
very dangerous. Even the most basic of home wiring books describes the
relationship between wire size and ampacity rating. It is NOT just "use
what works, or makes me feel right".
A 30 amp breaker is oversized for a 12 ga wire. You should start over
before you burn your house down.
> I ran #8 into the whole
> shop including a 5 HP compressor and a 5500 watt electric heater in
> the winter and a 2 1/2 ton air conditioner in the summer.
On what size breaker? Based on your "calculations" above, I'd guess 70 amp?
Fire waiting to happen!
jobel
You conclusions are right but you reasoning is wrong. The breaker is
there to prevent you from overloading the circuit and generally if you
have #14 wire it is fused at 15 amps and 12 is fused at 20 amps, but
that is not the whole story. The length of the wire has more to do
with how much current a circuit can carry. For short distances #12
will carry 50 amps. But don't try it with a #12 100 ft extension cord.
This is due to the resistance of the wire, the longer the wire the
more resistance. The more resistance the more voltage drop between the
source and the load, The more voltage drop the more watts dissipated
in the wire. Watts equals heat.To many watts to much heat, the wire
burns up. So the bottom line is really the length of the run. How ever
if you live in some areas the code may have other things to say about
it. The last time we saw a building inspector in this town he was lost
and just wanted directions
Also #12 solid will carry more current than stranded. This is because
the cross sectional area of solid wire is greater than stranded. hence
less resistance.
John Lehman
Daniel
basement. And I asked the electrical inspector what to do about my needfor
electricity in my garage, he said a 60 amp breaker, #8 wire to a panel in
the garage. About 45 feet away (attached garage). He was aware exactly what
I would be running for wwing equipment.
Daniel
"Matt W." <matt@*woodwork*worzala.com> wrote in message
news:oprlqw4z...@news.core.com...
jobel
It should have been 220 But I guess you couldn't figure that out.
John Lehman
Mark Winlund
"jobel" <jo...@pldi.net> wrote
My compressor is at the end of this run all on a 30 amp
> breaker and #12 wire.
I hope you have good fire insurance.... I woudn't mention your wiring
practices to your insurance agent, either.....
Mark
David A. Frantz
If this is a stationary piece of equipement that will be runniing to any
great extent then yes wiring direct would be the way to go. Providing
of course that you obey all the little details contained withing the NEC.
One of these that might apply would be the need for a disconnect if one
is not supplied.
The breaker should not be sized any larger than required to reliably run
the compressor. The wire running to the motor should be sized to
1. Properly handle the rating of the breaker selected. The wire should
never be less that what the breaker can properly protect.
2. Have its sized increased, if needed, to eliminate excessive voltage
drop.
3. Meet all other NEC requirements for feeding a motor load.
Hope this helps. At this moment in time I'm sticking with a hand me
down compressor so I don't have to deal with a proper instalaltion of a
stationary device.
Thanks
dave
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Phisherman
<michael...@cox.net> wrote:
>Hi I'm installing a large air compressor in my garage and have a couple
>questions.
>
>1) The instructions say to wire it straight to the fuse box (no outlet).
> Should I really do it this way or would it be ok to install an outlet
>in my garage? I would prefer that since it would be easier to unplug it
>if I have to move it for some reason.
That's a bit strange. It is better to install a receptacle outlet.
It is MUCH better to see an unplugged machine (than a circuit-breaker
switch) when you need to service it.
>
>2) I know I need 10 guage wire but is there any special kind? (Grade, etc..)
The regular Romex with ground for interior use should be fine.
>
>3) Should 30 amp breaker be good since the compressor uses 15 amps??
>
That sounds about right, a 20 amp breaker may blow during motor
startup. However something doesn't seem right ...
15*220=3300 watts = 4.4 HP
and somewhat less considering a power factor, yet you state your
compressor is 7 horsepower. I suspect your amperage is more than 15?
jobel
The wiring in my shop is more likely safer than the wiring in your
house. All run in conduit grounded with dust proof outlets. My 30 amp
breaker is perfectly legal with the way the wiring is installed. The
reason I use a 30 amp breaker is if I am running the table saw under
a full load and the compressor kicks in it will not trip the breaker
do to the current surge when the compressor starts. A safety factor
when running the saw.
As I said in an earlyer post some local codes will not allow you to do
this.
Matt W.
John, I respectfully disagree.
> The breaker is
> there to prevent you from overloading the circuit and generally if you
> have #14 wire it is fused at 15 amps and 12 is fused at 20 amps, but
> that is not the whole story.
Per the 1993 National Electrical Code (NEC) - Section 210-19
"The ampacity of a conductor must not be less than the rating of the
overcurrent device protecting that conductor."
The size of the wire is what determines the size of the breaker. Period. Of
course you must choose the wire sixe that matches the overall current
capacity you need.
> The length of the wire has more to do
> with how much current a circuit can carry. For short distances #12
> will carry 50 amps. But don't try it with a #12 100 ft extension cord.
> This is due to the resistance of the wire, the longer the wire the
> more resistance.
Wire size may need to be increased to compensate for voltage drop on longer
runs. But to say that length has MORE to do with ampacity than cross-
sectional area (size) is ludicrous. And dangerous.
> Also #12 solid will carry more current than stranded. This is because
> the cross sectional area of solid wire is greater than stranded. hence
> less resistance.
Per the 1993 National Electrical Code (NEC) - Table 310-6
Allowable Ampacities of Insulated Conductors
There is NO specification for a different ampacity rating using a solid or
stranded wire. They have the same cross-sectional area and the same
ampacity rating.
Thomas D. Horne
Both of you who have responded critically are neglecting the fact that
you are discussing a motor branch circuit which is an entirely different
animal than many other branch circuits. The conductors are sized to
1.25 of the largest motors current plus the sum of the current flows of
all other motors. The short circuit and ground fault protection is
sized in accordance with the appropriate table of the motor chapter of
the NEC and it is usually 150% to 300% of the full load motor current.
The overload protection installed at the motor protects the branch
circuit from overload in much the same way as a main breaker protects
the service entry conductors of the home from overload by limiting the
current that the load can draw. It is quite common to have motor branch
circuit with fault protection far larger than the wire can safely carry
for any length of time. The larger size of breaker or fuse is often
essential to allow the motor/s to start without nuisance tripping.
The code does not force you to use the smallest size that the tables
permit. You could up size the wire to the size of the breaker that is
necessary to permit the motor to start but that is certainly not
required. There are millions of motor circuits in use with similar
arrangement that operate safely every day.
That having been said if the "every other outlet" being described in
this particular case are general use receptacles that is a violation of
the US NEC.
--
Tom
jsdeboo
> Hi I'm installing a large air compressor in my garage and have a couple
> questions.
>
> 1) The instructions say to wire it straight to the fuse box (no outlet).
> Should I really do it this way or would it be ok to install an outlet
> in my garage? I would prefer that since it would be easier to unplug it
> if I have to move it for some reason.
>
> 2) I know I need 10 guage wire but is there any special kind? (Grade, etc..)
>
> 3) Should 30 amp breaker be good since the compressor uses 15 amps??
I'll bet you're sorry you asked that particular question in this WW forum huh?
I mentioned a good book a few months ago for doing electrical wiring and was
bombarded by zealots whining about wiring, lawsuits, insurance claims etc.
Christ, all Iwanted to do was recommend a decent read on wiring.
Got ahold of a book called Wiring 123 (bright golden hardback cover), libraries
have it usually, Home Depot carries it and I just bought a copy on clearence or
$6.99 @ Hastings. Anyway, it'll tell you whats up with wiring etc. From there
*YOU* can determine if you want to tackle it or have an electrician do it.
--
John S. DeBoo
jsd...@abq.com
Wade
> Hey I hit a wrong key so sue me
> It should have been 220 But I guess you couldn't figure that out.
No, I couldn't figure out how some moron could advise others to use
inadequate wire.
Perhaps you have heard that a 30a circuit requires 10awg, or do you figure
just 40' of it won't really matter?
You had better rethink that one. (or is the NEC one big "wrong key"?)
You want to keep going or will you leave now?
Wade
> The conductors are sized to
> 1.25 of the largest motors current plus the sum of the current flows of
> all other motors.
Please cite a code section.
My copy pretty clearly say that the OVERLOAD PROTECTION is 1.25 time the
motor's full load draw. Sure, the wire has to be that large also, but the
breaker can't be larger unless the wire is also, contrary to your claim.
ATP
> Matt
> You conclusions are right but you reasoning is wrong. The breaker is
> there to prevent you from overloading the circuit and generally if you
> have #14 wire it is fused at 15 amps and 12 is fused at 20 amps, but
> that is not the whole story. The length of the wire has more to do
> with how much current a circuit can carry. For short distances #12
> will carry 50 amps. But don't try it with a #12 100 ft extension cord.
> This is due to the resistance of the wire, the longer the wire the
> more resistance. The more resistance the more voltage drop between the
> source and the load, The more voltage drop the more watts dissipated
> in the wire. Watts equals heat.To many watts to much heat, the wire
> burns up. So the bottom line is really the length of the run. How ever
> if you live in some areas the code may have other things to say about
> it.
Almost all jurisdictions have adopted the National Electric Code, obviously
with various degrees of enforcement and some have added more restrictive
provisions (such as NYC). The NEC looks at how hot a given wire will get at
different ampacities and whether or not the insulation on the wire is rated
to take it. This is reflected in Table 310-16, although small branch
circuits are not allowed to utilize the full ampacity of THHN and are rated
more conservatively. The length of the circuit may increase total amperage
draw with an inductive load, but length of the circuit has no bearing on
ampacity calculations for branch circuits. Internal wiring on utilization
devices is often smaller for the reasons John stated, but even if a branch
circuit was only a one foot home run to the panel a 30 amp circuit would
require a #10 wire. (unless covered by an exception for refrigeration or A/C
Jeff Cochran
>
>> The breaker is
>> there to prevent you from overloading the circuit and generally if you
>> have #14 wire it is fused at 15 amps and 12 is fused at 20 amps, but
>> that is not the whole story.
>
>Per the 1993 National Electrical Code (NEC) - Section 210-19
>"The ampacity of a conductor must not be less than the rating of the
>overcurrent device protecting that conductor."
"Not less than" also means "can be more than".
>The size of the wire is what determines the size of the breaker. Period.
Ahhh... No. The size of the breaker determines a minimum wire size.
You can always upsize the wire. You can't downsize it below the
breaker requirement.
Jeff
Matt W.
wrote:
> "Not less than" also means "can be more than".
>
>> The size of the wire is what determines the size of the breaker. Period.
>
> Ahhh... No. The size of the breaker determines a minimum wire size.
> You can always upsize the wire. You can't downsize it below the
> breaker requirement.
Jeff,
I never meant to say you can't OVERsize any wire. Only that you can't
UNDERsize. Sorry if that wasn't clear. The overcurrent device is there to
protect the wire. It's NOT sized according to the needs of the circuit, the
WIRE is sized according to the needs of the circuit, the OCD is sized to
protect the wire (of course, it's mostly a chicken and egg thing, one leads
to the other). Many people put in larger wire than is needed right now, so
that in the future, if they need to use higher amperage equipment, they
can. That's not a problem. I didn't see anywhere in any of the posts that
people were concerned about OVERsized wire. Only with the recommendation to
use undersized wire.
Matt W.
<hor...@mindspring.com> wrote:
> That having been said if the "every other outlet" being described in this
> particular case are general use receptacles that is a violation of the US
> NEC.
Bingo!
Tbone
I would like to see the code that allows this.
--
If at first you don't succeed, you're not cut out for skydiving
volts500
"Michael Shaffer" <michael...@cox.net> wrote in message
news:3E6A9525...@cox.net...
We can't answer your questions until we know the _actual_ motor nameplate HP
and or FLA (Full Load Amps). That 7 HP number is useless because it is the
Tim Allen (arrrrrrrr, arrrrrrr) _developed_ HP..........we need actual HP,
not developed. When you say the compressor "uses 15 amps," that helps some,
but is still not specific enough. Is the 15 amps the motor FLA or the
"minimum circuit ampacity?"
The usual way to wire a compressor like that is to run a circuit from the
main panel to a fused disconnect at the compressor, then use 1/2 inch
Greenfield flex to the compressor from the disconnect..........if you need
to move the compressor simply turn off the disconnect, remove the wires
from the lugs, remove the locknut on the flex connector and pull the flex
whip out......about a 2 minute job.
Tbone
> questions.
>
> 1) The instructions say to wire it straight to the fuse box (no outlet).
> Should I really do it this way or would it be ok to install an outlet
> in my garage? I would prefer that since it would be easier to unplug it
> if I have to move it for some reason.
Sure, just make sure that the compressor has the ability to properly anchor
the cord that you want to use.
>
> 2) I know I need 10 guage wire but is there any special kind? (Grade,
etc..)
Wire size is dependant on the breaker that you intend to use. Many
electrical codes require both the common and a ground be connected at the
outlet with the branch connections so use 10/3 with ground. If the wire is
going to be exposed then you will probably need to use conduit to protect
it.
>
> 3) Should 30 amp breaker be good since the compressor uses 15 amps??
The breaker is not there to protect the compressor, it is there to protect
the circuit. A thirty amp breaker is fine for 10 guage wire but make sure
that the outlet you are going to use is also rated for 30 Amps.
>
> Thanks
>
>
> BTW here's the compressor
>
> -----------------------------------------------------------------------
>
> http://www.sears.com/data/product_images/tools/large/00918419000-dlv.jpg
>
> Craftsman 60 gal. Air Compressor, 7 hp, Vertical Tank, Oillube Pump
> Air compressor features 150 psi and motor has thermal overload
> protection. Has a 2 cyclinder oillube pump and provides large air
> storage space in a minimum amount or air space with its 60 gal. tank.
>
> Can have heavy-duty use of most air tools and is made of durable
> construction with lower oil consumption for longer pump life. It has an
> improved dissipation of heat for better filtration and a globe valve
> included. It also has an automotive type paper filter that is for better
> filtration.
> $449
Thomas D. Horne
What you are loosing track of is that the overload protection can be
located at the motor. The breaker protecting the branch circuit from
fault is not the overload protection for the circuit. Mike Holt just
sent out a great tutorial to subscribers that makes the very point I'm
trying to make.
--
Tom
430.52 Rating or Setting for Individual Motor Circuit.
(A) General. The motor branch-circuit short-circuit and ground-fault
protective device shall comply with 430.52(B) and either 430.52(C) or
(D), as applicable.
(B) All Motors. The motor branch-circuit short-circuit and ground-fault
protective device shall be capable of carrying the starting current of
the motor.
(C) Rating or Setting.
(1) In Accordance with Table 430.52. A protective device that has a
rating or setting not exceeding the value calculated according to the
values given in Table 430.52 shall be used.
Table 430.52 Maximum Rating or Setting of Motor Branch-Circuit
Short-Circuit and Ground-Fault Protective Devices
Percentage of Full-Load Current
Type of Motor Nontime Delay Fuse1 Dual Element (Time-Delay) Fuse1
Instantaneous Trip Breaker Inverse Time Breaker2
Single-phase motors 300 175 800 250
AC polyphase motors other than wound-rotor
Squirrel cage -- other than Design E or Design B energy efficient
300 175 800 250
Design E or Design B energy efficient 300 175 1100 250
Synchronous3 300 175 800 250
Wound rotor 150 150 800 150
Direct current (constant voltage) 150 150 250 150
Note: For certain exceptions to the values specified, see 430.54.
1The values in the Nontime Delay Fuse column apply to Time-Delay Class
CC fuses.
2The values given in the last column also cover the ratings of
nonadjustable inverse time types of circuit breakers that may be
modified as in 430.52(C), Exception No. 1 and No. 2.
3Synchronous motors of the low-torque, low-speed type (usually 450 rpm
or lower), such as are used to drive reciprocating compressors, pumps,
and so forth, that start unloaded, do not require a fuse rating or
circuit-breaker setting in excess of 200 percent of full-load current.
Exception No. 1: Where the values for branch-circuit short-circuit and
ground-fault protective devices determined by Table 430.52 do not
correspond to the standard sizes or ratings of fuses, nonadjustable
circuit breakers, thermal protective devices, or possible settings of
adjustable circuit breakers, a higher size, rating, or possible setting
that does not exceed the next higher standard ampere rating shall be
permitted.
Exception No. 2: Where the rating specified in Table 430.52, as modified
by Exception No. 1, is not sufficient for the starting current of the
motor:
(a) The rating of a nontime-delay fuse not exceeding 600 amperes or a
time-delay Class CC fuse shall be permitted to be increased but shall in
no case exceed 400 percent of the full-load current.
(b) The rating of a time-delay (dual-element) fuse shall be permitted to
be increased but shall in no case exceed 225 percent of the full-load
current.
(c) The rating of an inverse time circuit breaker shall be permitted to
be increased but shall in no case exceed 400 percent for full-load
currents of 100 amperes or less or 300 percent for full-load currents
greater than 100 amperes.
(d) The rating of a fuse of 601-6000 ampere classification shall be
permitted to be increased but shall in no case exceed 300 percent of the
full-load current.
FPN:See Annex D, Example D8, and Figure 430.1.
430.53 Several Motors or Loads on One Branch Circuit.
Two or more motors or one or more motors and other loads shall be
permitted to be connected to the same branch circuit under conditions
specified in 430.53(D) and in 430.53(A), (B), or (C).
(B) If Smallest Rated Motor Protected. If the branch-circuit
short-circuit and ground-fault protective device is selected not to
exceed that allowed by 430.52 for the smallest rated motor, two or more
motors or one or more motors and other load(s), with each motor having
individual overload protection, shall be permitted to be connected to a
branch circuit where it can be determined that the branch-circuit
short-circuit and ground-fault protective device will not open under the
most severe normal conditions of service that might be encountered.
Mike
12 gauge copper type TW wire has a maximum capacity of 25 amps in a
cable and SHALL BE USED WITH A MAXIMUM OVERCURRENT PROTECTION DEVICE
(breaker) of 20 AMPS.
(You really should change your 30 amp breakers to 20 amp breakers.
Your compressor will still run fine and not trip the 20 amp breakers).
10 gauge copper is rated at 30 amps in a cable.
Wire ratings are based in part on how well the wire can disipate heat
do to resistance and the heat rating of the insulation. Because
"romex" is individually insulated wires wrapped with plastic it has
lower ampacity ratings than free run wire not wrapped in plastic to
make a cable. The purpose of a over current protection device (Circut
breaker) is to ensure that a wire does not carry more current than it
is rated for, heat up and cuase a fire. There are hundreds of sites
that list capacity ratings of wire here is one:
http://www.desertelectric.com/knowhow/table3.htm
I am pretty sure romex type wire used most commonly in residents is
type T or TW.
I always thought that all the hassle of inspections was just a
headache to make life misserable. I guess I couldn't believe that
someone wouldn't take the 15 minutes to research what they were doing,
spend the extra couple of bucks to purchase the correct materials and
then do a wiring job properly in there own home. The more I read this
forum the more I realize that this is not the case and inspectors
should be more intrusive!
Dr. Know
<michael...@cox.net> wrote:
>Hi I'm installing a large air compressor in my garage and have a couple
>questions.
>
>1) The instructions say to wire it straight to the fuse box (no outlet).
> Should I really do it this way or would it be ok to install an outlet
>in my garage? I would prefer that since it would be easier to unplug it
>if I have to move it for some reason.
>
>2) I know I need 10 guage wire but is there any special kind? (Grade, etc..)
>
>3) Should 30 amp breaker be good since the compressor uses 15 amps??
The updated 2002 NEC has guidelines that you should follow.
One thing you may miss, however, is that if there is no disconnect
(plug/socket) on the compressor, the breaker must be line of site and
within 50 feet. Also, you may have to use High Magnetic Trip Breakers
to handle the inrush current of the induction motor. Home breakers
are designed to trip quite quickly, and my cause annoyance tripping
when starting up loads such as large motors.
General guidelines:
10 gauge = 30 amps,
12 gauge = 20 amps,
14 gauge = 15 amps.
Wire size may be larger, never smaller.
It is to your advantage to insure that your wiring meets code - NEC
and any local perversions - and that it be inspected. Failing that,
should something go wrong - fire, etc. - your insurance company can
refuse to pay.
Self Help electrical forum run by an electrical inspector:
http://www.selfhelpforums.com/viewforum.php?f=16
General home wiring help:
http://www.homewiringandmore.com/
G
Wade
not cause nuisance trips; only that you also have to use wire sized to the
breaker.
Nothing in your long quote allowed smaller wire.
Michael Shaffer
7HP
jobel wrote:
> Need to ask a couple of questions.
> 1: How far from the breaker box it the compressor? That Is how much
> wire will it take to make the run between the breaker box and the
> compressor?
> 2; What is the HP of your compressor?
>
> From what you have said in your post an out let should be no problem
> and if the run is under 30 feet # 12 - 2 with ground wire is more
> than adaquite.. My compressor is 5HP and I run it almost 40 ft on #12
> wire no problem. In fact when I wired my shop I wired 229 through out
> making every other outlet off a different leg. This serves two purpose
> on is to balance the load if I am running more than one machine the
> other is to have 220 available any where that I might need it in the
> future, My compressor is at the end of this run all on a 30 amp
> breaker and #12 wire. Never thrown a breaker. I use a 20 amp plug to
> plug my compressor into the line. If you had several 100 feet of wire
> between your breaker box and the compressor I might think you would
> need #10. In my last shop I had about a 100 ft run to make from the
> maine breaker to the sub panel in the shop and I ran #8 into the whole
> shop including a 5 HP compressor and a 5500 watt electric heater in
> the winter and a 2 1/2 ton air conditioner in the summer.
> John Lehman
>
>
> On Sun, 09 Mar 2003 01:13:06 GMT, Michael Shaffer
> <michael...@cox.net> wrote:
>
>
>>Hi I'm installing a large air compressor in my garage and have a couple
>>questions.
>>
>>1) The instructions say to wire it straight to the fuse box (no outlet).
>> Should I really do it this way or would it be ok to install an outlet
>>in my garage? I would prefer that since it would be easier to unplug it
>>if I have to move it for some reason.
>>
>>2) I know I need 10 guage wire but is there any special kind? (Grade, etc..)
>>
>>3) Should 30 amp breaker be good since the compressor uses 15 amps??
>>
Gary Coffman
>You conclusions are right but you reasoning is wrong. The breaker is
>there to prevent you from overloading the circuit and generally if you
>have #14 wire it is fused at 15 amps and 12 is fused at 20 amps, but
>that is not the whole story. The length of the wire has more to do
>with how much current a circuit can carry. For short distances #12
>will carry 50 amps. But don't try it with a #12 100 ft extension cord.
>This is due to the resistance of the wire, the longer the wire the
>more resistance. The more resistance the more voltage drop between the
>source and the load, The more voltage drop the more watts dissipated
>in the wire. Watts equals heat.To many watts to much heat, the wire
>burns up. So the bottom line is really the length of the run. How ever
>if you live in some areas the code may have other things to say about
>it. The last time we saw a building inspector in this town he was lost
>and just wanted directions
This is incorrect, and potentially dangerous advice. It is true that total
resistance increases with increasing wire length, and that may manifest
as voltage sag at the load. But the insulation heating a wire can tolerate
is solely due to its resistance per unit length. That's only a function of
wire gauge. In other words, it doesn't matter so much how much energy
the entire wire dissipates, what matters is how much it dissipates at any
given point along the wire.
A long wire may dissipate a lot of energy, but it does so over a lot of
surface area. For any wire, the amount of heat per unit length determines
how hot its insulation will become. That's the critical factor for safety.
The Code's ampacity tables are based on wire gauge and insulation
temperature rating for this reason.
Gary
jobel
>Need to ask a couple of questions.
>1: How far from the breaker box it the compressor? That Is how much
>wire will it take to make the run between the breaker box and the
>compressor?
>2; What is the HP of your compressor?
>
>From what you have said in your post an out let should be no problem
>and if the run is under 30 feet # 12 - 2 with ground wire is more
>than adaquite..
>
with information given #12- 2 with ground should be adequate for his
compressor especially if it was a short run. If you have a long run of
several 100 ft then I would go to a larger wire size because the
losses in the wire and could damage the motor because of low voltage
at start up.
Second I stated that the wireing in my shop is in conduit but
neglected to say that it was 3 #12 solid conductors plus ground run
through out. It is not romex. I would prefer to use a 25 amp breaker
but have been unable to find on for my breaker box. And I feel
comfortable with the 30 in there.
\
Next point A compressor only runs for a few minutes at a time and it
is not long enough to worry about wire heating unless the circuit is
seriously overloaded to begin with. In this case we were talking
about a dedicated run just for the compressor.
Next Item The cross sectional area of #12 solid and #12 stranded is
different. Most #12 stranded wire is 6 conductors around 1 conductor.
This creates small gaps there for less copper in the same cross
sectional area. The code makes no destination between them because
for the safety factors in the built into the code. But there is an 10
to 15 % loss in cross sectional area between solid and stranded.
Next I do not appreciate being called a moron . I was not telling him
to do any thing wrong and said several times that the local code may
not permit hooking it up that way. But if you live in the country like
I do you can do just about anything you want. When we remolded this
house I found several outlets with out boxes and caulking used to hold
them in the wall.
No some idiot will come back and say that I was telling him to just
caulk the outlet to the wall.
volts500
purpose circuits.
"Wade" <wlip...@yahoo.com> wrote in message
news:v6mgcuq...@corp.supernews.com...
Wade, you are arguing against a point that is common knowledge to _anyone_
who knows motor wiring. Get your (2002 NEC) code book and follow along if
you can. A 1999 or 1996 NEC code book will suffice, only the referenced
Section
numbers will be different, and the wording slightly different. The
principles are the same.
See Table 310.16. See the asterisk (*) next to the 14, 12, and 10 gauge
wires? The asterisk at the bottom of the page says to "see 240.4(D)". What
does Section 240.4(D) say? :
240.4 Protection of Conductors.
240.4(D) Small Conductors: "UNLESS SPECIFICALLY PERMITTED IN 240.4(E)
THROUGH (G), the overcurrent protection shall not exceed 15 amperes for 14
AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper........and so
on."
Now look at 240.4(G):
240.4(G) Overcurrent Protection for Specific Conductor Applications.
"Overcurrent protection for the specific conductors SHALL BE PERMITTED as
referenced in Table 240.4(G)."
Look at Table 240.4(G) Specific Conductor Applications. You will see MOTORS
listed in this table (Article 430, Parts III, IV, V, VI, VII)
GOT IT so far?
Look at Article 430, Part IV. Motor Branch-Circuit Short-Circuit and
Ground-Fault Protection
430.52 Rating or Setting for Individual Motor Circuit.
430(A) General. "The motor branch-circuit short-citrcuit and ground-fault
protective device SHALL comply with 430.52(B) and either 430.52(C) or (D),
as applicable."
What does Section 430.52(B) say? "The motor branch-circuit short-circuit
and ground fault protective device shall be capable of carrying the starting
current of the motor."
Section 430.52(C) Rating or setting.
Section 430.52(C)(1) "In Accordance with Table 430.52. A protective device
that has a rating or setting not exceeding the value calculated according to
the values given in Table 430.52 shall be used...........and so on"
What does Table 430.52 (Maximum Rating or setting of Motor branch-Circuit
Short-Circuit and Ground-Fault Protective Devices) say? For a single-phase
motor, the percentage of Full-Load Current for a Nontime Delay Fuse is 300%,
for a Dual Element (Time-Delay) Fuse, 175%, and 250% for an Inverse Time
Breaker.
What does all this mean? As an example, lets say that the OP's compressor
motor is really a 3 HP motor (we know that the _developed_ HP is 7HP, which
cannot be used for the calculation.)
Looking at Table 430.148 (Full-Load Currents in Amperes, Single Phase
Alternating-Current Motors), one sees that the FLA for a 3 HP, 230 volt,
single-phase motor is 17 amps. Taking 125% of 17 amps (from 430.22) one
gets 21.25 amps. The _minimum_ ampacity of the _conductors_ MUST_ be 21.25
amps. Looking at Table 310.16 again, and assuming that romex is used
(reading from the 60 degree C column per 334.80), one determines that a #12
romex is required (good for 25 amps in this case.)
Now figure the fuse/breaker size. For a nontime-delay fuse: 17amps x 300% =
51 amps. Since 430.52(C)(1) Exception No. 1 permits going to the next
standard size fuse, per 240.6, up to a 60 amp nontime-delay fuse can be
used on the #12 wire for the motor.
For a time-delay fuse: 17amps x 175% = 29.75amps, up to a 30 amp time-delay
fuse can be used on the #12 wire for the motor.
For an inverse-time breaker: 17 amps x 250% = 42.5amps, up to a 45amp
inverse-time breaker can be used on the #12 wire for the motor.
Good wiring practice is to use the _lowest_ fuse/breaker that will allow
the motor to start. That is why I recommended to the OP in another post
that the usual practice is to install a fused disconnect at the compressor,
so that lowest possible fuse can be used. In this 3HP example, I would
start with a 20 amp time-delay fuse.........if that didn't hold, try a 25amp
TD, and so on.........NOT to exceed a 30 amp TD fuse, as calculated.
As far as OVERLOAD protection for the motor, the motor has a built-in
thermal overload protector.........otherwise one would also have to provide
a motor starter with correctly sized overloads.
Sorry about the long post, but sometimes there is more to electrical work
than a roll of baling wire and a set of Kleins.
Nate B
"Michael Shaffer"
> 10 feet (breaker is in basement near garage)
> 7HP
Your plan is fine. I would drop the breaker down to 20 amps or so, just to
make myself feel better about protecting the compressor - even though the
motor has its own protection. The owner's manual for these larger motors
usually suggests a breaker size.
Consider: I just ran a 220 out to the garage, but I used 6 ga wire.
Everything got drywalled over after, so another run later is almost
impossible w/o significant demo. With the thicker wire, I have more
flexibility. Arc welder, sub panel, even a simple compressor. In the
immediate future, I'm going to run a Unisaw with it, probably 20 amp
breaker. Judging from the amount of money you spent on the compressor, a
couple extra bucks on wire won't kill your budget. The voltage drop will be
slightly decreased by thicker wire (no big deal in your situation), and you
will also be way compliant on code.
- Nate
Matt W.
wrote:
> Please note: The following comments do NOT apply to standard general
> purpose circuits.
<SNIP>
> Get your (2002 NEC) code book and follow along if
> you can. A 1999 or 1996 NEC code book will suffice, only the referenced
> Section
> numbers will be different, and the wording slightly different. The
> principles are the same.
<SNIP>
> Sorry about the long post, but sometimes there is more to electrical work
> than a roll of baling wire and a set of Kleins.
Volts,
This is an excellent run-through of the different considerations that need
to be considered where motor branches are being run. No need to apologize
for the length. I, for one, appreciate it. Thank you. I will keep this post
for future reference. I was under the impression that for any NEC
exceptions to "General Purpose" branches to be granted, the equipment HAD
to be hard-wired. And that anytime you put in a receptacle, the branch
becomes General Purpose. (With a few exceptions like the GFCI exception for
sump pumps and freezers.) Is that true?
I've never wired any dedicated motor circuits (and am not likely to have
the need to) because everything that I do is homeowner related and I've
never had a motor hard-wired (except for A/C units) in a residential
application. I'm not an electrician by trade, which is probably obvious by
now, but I study up on anything I do, and I even took a home wiring class
at one time to help me learn. I feel very comfortable doing home wiring
projects for myself and friends. I never will and never intend to make a
living at it. I generally live by the "rule-of-thumb" and if I don't know,
I don't guess; I ask a pro or the building inspector. I do know a few
things about electricity, however, as I was an Aviation Electrician for 11
years with a major airline.
To Jobel (John). I apologize for a somewhat mean-spirited attitude in one
of my earlier posts. While I do not engage in name-calling on Usenet, and
never will, I did act too mean-spirited in my response. I guess I was
having a bad day. No excuse, I'm sorry.
To all... I've enjoyed the discussion. I have learned from it (as always)
and hope I've contributed in some small way. That's what this forum is for.
Thanks,
Douglas Miller
>On Sat, 8 Mar 2003 18:43:22 -0800, "Mark Winlund"
><ma...@maxmachine.com> wrote:
>
>>
>>"jobel" <jo...@pldi.net> wrote
>>
>>My compressor is at the end of this run all on a 30 amp
>>> breaker and #12 wire.
>>
>>I hope you have good fire insurance.... I woudn't mention your wiring
>>practices to your insurance agent, either.....
>>
>>
>>Mark
>The wiring in my shop is more likely safer than the wiring in your
Very doubtful.
>house. All run in conduit grounded with dust proof outlets. My 30 amp
>breaker is perfectly legal with the way the wiring is installed. The
No, sorry, it's not. At least, not if you're in a jurisdiction that has
adopted the National Electrical Code. The maximum overcurrent protection
permitted under the NEC for 12ga wire is 20A, not 30. Putting 30A breakers on
a circuit wired with 12ga wire is absolutely a violation of the NEC, and is
not safe.
>reason I use a 30 amp breaker is if I am running the table saw under
>a full load and the compressor kicks in it will not trip the breaker
>do to the current surge when the compressor starts. A safety factor
>when running the saw.
>As I said in an earlyer post some local codes will not allow you to do
>this.
Kind of an understatement, actually, since the *national* code does not allow
it. I wonder if you can point to *any* local code that *does* allow it.
--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)
Save the baby humans - stop partial-birth abortion NOW
Dell Phinus
> questions.
>
> 1) The instructions say to wire it straight to the fuse box (no outlet).
> Should I really do it this way or would it be ok to install an outlet
> in my garage? I would prefer that since it would be easier to unplug it
> if I have to move it for some reason.
>
> 2) I know I need 10 guage wire but is there any special kind? (Grade, etc..)
>
> 3) Should 30 amp breaker be good since the compressor uses 15 amps??
>
> Thanks
>
>
> BTW here's the compressor
>
> -----------------------------------------------------------------------
>
> http://www.sears.com/data/product_images/tools/large/00918419000-dlv.jpg
>
> Craftsman 60 gal. Air Compressor, 7 hp, Vertical Tank, Oillube Pump
> Air compressor features 150 psi and motor has thermal overload
> protection. Has a 2 cyclinder oillube pump and provides large air
> storage space in a minimum amount or air space with its 60 gal. tank.
>
> Can have heavy-duty use of most air tools and is made of durable
> construction with lower oil consumption for longer pump life. It has an
> improved dissipation of heat for better filtration and a globe valve
> included. It also has an automotive type paper filter that is for better
> filtration.
> $449
There have been a lot responses to this that are mis-applying the NEC.
Mr. Horne is correct.
For motors, you size the conductors based on the namplate current
ratings ON THE MOTOR, or you use the HP to amps table in the NEC; the
NEC tells you when to use nameplate and when to use tables.
If it's a continuous duty motor, you size it to 125% of the FLA. If
it's more than one motor or combination loads on the circuit you size
the conductors to 125% of the largest, plus the others at 100%, plus
the combo loads.
Once you have the wire size picked, then you protect it UP TO 250% of
the FLA of the motor. If that value trips during start up, you can go
up to 400%.
YOU DO NOT HAVE TO RESIZE THE CONDUCTORS TO THE SIZE OF THE BREAKER.
The motor protection circuit (in the motor) protects the conductors
against overload. The breaker protects against shorts.
So it would be possible to end up with a 30 (even 50) amp breaker on
12 gage wire. Legally, safely, and properly.
You CAN oversize the wires, and many do, but you do not HAVE to.
Voltage drop SHOULD be a player, and may drive a wire size increase.
Again, pick the wires to let it run, pick the breaker to let it start.
Read article 430.
I'd recommend that anyone that can, get a copy of the 99 or 02 NEC
handbook from the library, or borrow or buy one, and read it cover to
cover. You'll be amazed at how much stuff you've heard as gospel over
the years is not to code.
To the guy with the multiple outlets, 8 gage and compressor on the
end, I ain't smart enough to figure that one out, but something don't
sound right. The fact that you have 120 volt 15/20 amp outlets on a
30 amp circuit IS a violation however, I'm pretty sure, if indeed that
is what you described.
jobel
these hardheads.
John Lehman
On 9 Mar 2003 11:30:44 -0800, dellp...@my-deja.com (Dell Phinus)
wrote:
Wade
Since code is very conservative, it must be perfectly safe; but putting a
45a breaker on #12 just doesn't seem right to me.
jobel
Your apology is accepted
John Lehman
Larry Caldwell
> I just had an electrical inspection done for a couple bedrooms I did in my
> basement. And I asked the electrical inspector what to do about my needfor
> electricity in my garage, he said a 60 amp breaker, #8 wire to a panel in
> the garage. About 45 feet away (attached garage). He was aware exactly what
> I would be running for wwing equipment.
You heard wrong. #8 copper is good for 40 amps. For a 60 amp breaker,
you need #4 copper.
Larry Caldwell
> Wire size is dependant on the breaker that you intend to use. Many
> electrical codes require both the common and a ground be connected at the
> outlet with the branch connections so use 10/3 with ground. If the wire is
> going to be exposed then you will probably need to use conduit to protect
> it.
That's what I thought. If he hard wires it he doesn't have to establish
a neutral for a balanced load, but if he wires a receptacle he has to run
both a neutral and a ground to the receptacle and use a 4 hole
receptacle.
volts500
> Thank you, your explanation was very clear.
>
> Since code is very conservative, it must be perfectly safe; but putting a
> 45a breaker on #12 just doesn't seem right to me.
Maybe this will help: Don't think in terms of the circuit being loaded to
45 amps......it isn't......under normal conditions any current over 125% of
the 17 amps (FLA) is only short-time and temporary under starting
conditions. Since 21.25 amps (17 x 125%) is the max. current draw (under
normal conditions) and the wire is good for 25 amps, the wires are not
overloaded.
In my example of then 3HP motor, the _overloads_ built into the motor (not
to be confused with a circuit breaker or fuse) protect the motor and the
wiring. In the
event of a sustained overload on the motor or a locked-rotor condition, the
motor_overloads_ are expected to function, not the fuses/breakers (they may
or may not). In the event of a short-circuit or ground-fault condition, the
fuses/breakers are expected to function......not the motor overloads.
Note that all motors do not have built-in overloads and the motors that
don't_must_ have (in ADDITION to the fuses/breakers) a separate motor
starter with the appropriate sized overloads installed.
The built-in thermal motor overloads are usually set
by the factory at 125% (or a bit higher) of the motor FLA.......that's why
the supply wires _must_ be capable of carrying 125% of the motor FLA. The
only function of the fuse/circuit breaker, in the case of a motor, is to
provide short-circuit and ground-fault protection. Since a very high
current flows in the event of either case (note that there _is_ a limit to
this per NEC....thus the 300%, 175%, and 250% numbers for the percentage of
FLA from Table 430.52 _NOT_ TO BE EXCEEDED), it has been determined by the
NEC that the higher fuses/circuit breakers are sufficient to provide
short-circuit and ground-fault protection (ONLY).
The fuses/breakers don't provide overload protection and the motor overloads
don't provide short-circuit and ground-fault protection.....but both working
_together_, full protection is obtained. This may not be obvious on motors
with built-in thermal overload protectors.....simply because one doesn't see
the motor thermal overloads.
Thomas D. Horne
Larry
You only need a grounded conductor connection to a receptacle if the
receptacle is of one of the patterns that is for connection of that
conductor to the equipment that will be run from the receptacle. There
are many receptacles that have no terminal for connecting the grounded
conductor.
--
Tom
Daniel
like LOL.
"Larry Caldwell" <lar...@teleport.com> wrote in message
news:MPG.18d569085...@news.earthlink.net...
Tbone
circuit with an outlet. Since anything can be plugged into it, don't think
that dedicated motor rules apply here.
--
If at first you don't succeed, you're not cut out for skydiving
"Dell Phinus" <dellp...@my-deja.com> wrote in message
news:4b88a248.03030...@posting.google.com...
Thomas D. Horne
Larry
He is right sixty amperes is too large a breaker to provide overload
protection to that 8 gauge feeder. If you draw sixty amps through eight
gauge THHN or even XHHW-2 the insulation will fail and dangerous arcing
may occur. Unless that breaker is sized as ground fault and short
circuit protection for motor loads and you have other overload
protection for that circuit you should reduce the breaker size to forty
amperes or change the wire size to 4 AWG.
--
Tom
Daniel
"Thomas D. Horne" <hor...@mindspring.com> wrote in message
news:3E6BFB21...@mindspring.com...
Mark Winlund
"jobel" <jo...@pldi.net> wrote in message
news:d98l6v419s60tqnvk...@4ax.com...
> Matt
> You conclusions are right but you reasoning is wrong. The breaker is
> there to prevent you from overloading the circuit and generally if you
> have #14 wire it is fused at 15 amps and 12 is fused at 20 amps, but
> that is not the whole story. The length of the wire has more to do
> with how much current a circuit can carry. For short distances #12
> will carry 50 amps. But don't try it with a #12 100 ft extension cord.
> This is due to the resistance of the wire, the longer the wire the
> more resistance. The more resistance the more voltage drop between the
> source and the load, The more voltage drop the more watts dissipated
> in the wire. Watts equals heat.To many watts to much heat, the wire
> burns up. So the bottom line is really the length of the run. How ever
> if you live in some areas the code may have other things to say about
> it. The last time we saw a building inspector in this town he was lost
> and just wanted directions
> the cross sectional area of solid wire is greater than stranded. hence
> less resistance.
> John Lehman
Wow. No disrespect intended, but you really need to have an electrician do
the work for you. Nearly everything you have said is incorrect, and would
be an extreme danger to yourself and your family.
Regards,
Mark
Mark Winlund
> On Sat, 8 Mar 2003 18:43:22 -0800, "Mark Winlund"
> <ma...@maxmachine.com> wrote:
>
> >
> >"jobel" <jo...@pldi.net> wrote
> >
> >My compressor is at the end of this run all on a 30 amp
> >> breaker and #12 wire.
> >
> >I hope you have good fire insurance.... I woudn't mention your wiring
> >practices to your insurance agent, either.....
> >
> >
> >Mark
> The wiring in my shop is more likely safer than the wiring in your
> breaker is perfectly legal with the way the wiring is installed. The
> a full load and the compressor kicks in it will not trip the breaker
> do to the current surge when the compressor starts. A safety factor
> when running the saw.
> As I said in an earlyer post some local codes will not allow you to do
> this.
Gentlemen, this is beginning to sound like a troll.... He clearly is
behaving in a confrontational manner. As long as the less experienced
members of the group understand that this person is *giving unsafe and bad
advice* apparently in order to cause arguments, it would be best to ignore
him.
Mark
jobel
facts. Better read it again. Also read all the post before putting you
2 cents in
On Sun, 09 Mar 2003 10:00:45 -0500, Gary Coffman <ke...@bellsouth.net>
wrote:
Gary Coffman
>First off Gary There is no faulty advice given in this post only
>facts. Better read it again. Also read all the post before putting you
>2 cents in
I read it. Your "facts" are incorrect, as is your physics. You've
demonstrated true, and at this point I might add willful, ignorance
with respect to the thermodynamics of electrical heating in an
extended linear structure.
Gary
Gary Coffman
>Are you sure about this Dell??? Remember, he intends to terminate this
>circuit with an outlet. Since anything can be plugged into it, don't think
>that dedicated motor rules apply here.
They don't.
Gary
Tom Horne
> "Thomas D. Horne" <hor...@mindspring.com> wrote in message
> news:3E6BFB21...@mindspring.com...
>
>>Daniel wrote:
>>
>>>Well, heck I'll give you the name of the sask-power employee if you
>>>would like LOL.
>>Larry
>>protection to that 8 gauge feeder. If you draw sixty amps through eight
>>gauge THHN or even XHHW-2 the insulation will fail and dangerous arcing
>>may occur. Unless that breaker is sized as ground fault and short
>>circuit protection for motor loads and you have other overload
>>protection for that circuit you should reduce the breaker size to forty
>>amperes or change the wire size to 4 AWG.
>>--
>>Tom
>>
>
>
not run in type NM cable. If you need to use cable then use type SE.
Do not use type USE! The US NEC would permit type NM with #6 AWG THHN
conductors, because the ampacity of the conductors does not correspond
to a standard breaker size, but the CEC may not.
--
Tom
Dell Phinus
I can't find anything in the code to indicate the rules are different
for circuits with dedicated motor loads and receptacles. 210
specifically states it does not apply to motor branch circuits. 430
gives requirements for the plug and receptacle; they must be HP rated.
If anyone has code references that say the motor rules don't apply,
please post 'em; I'm no expert here and always looking to learn...
Bottom line on this is the compressor manual specifically states that
it is to be permanently wired, and is a "fixed" unit. Since it is
being installed in vioaltion of it's instructions, it's no longer
"listed" and anything you do is not in compliance. The AHJ could deny
it based on that alone.
430.19(F) Cord-and-Plug-Connected Motors. For a
cord-and-plug-connected motor, a horsepower-rated attachment plug and
receptacle having ratings no less than the motor ratings shall be
permitted to serve as the disconnecting means for other than a Design
E motor and for a Design E motor rated 2 hp or less. For a Design E
motor rated more than 2 hp, an attachment plug and receptacle used as
the disconnecting means shall have a horsepower rating not less than
1.4 times the motor rating. A horsepower-rated attachment plug and
receptacle shall not be required for a cord-and-plug-connected
appliance in accordance with 422.32, a room air conditioner in
accordance with 440.63, or a portable motor rated 1/3 hp or less.
Tbone
> "Tbone" <Fatc...@noway.now> wrote in message
news:<ovucnXpnILV...@comcast.com>...
> > Are you sure about this Dell??? Remember, he intends to terminate this
> > circuit with an outlet. Since anything can be plugged into it, don't
think
> > that dedicated motor rules apply here.
> I can't find anything in the code to indicate the rules are different
> for circuits with dedicated motor loads and receptacles. 210
> specifically states it does not apply to motor branch circuits. 430
> gives requirements for the plug and receptacle; they must be HP rated.
> If anyone has code references that say the motor rules don't apply,
> please post 'em; I'm no expert here and always looking to learn...
Me either and that is why I'm questioning that. Remember, this is a
residential property, not commercial and if he moves, the next person can
plug anything (like a big welder) into that outlet that may be within range
of that breaker but overtax the wiring.
>
> Bottom line on this is the compressor manual specifically states that
> it is to be permanently wired, and is a "fixed" unit. Since it is
> being installed in vioaltion of it's instructions, it's no longer
> "listed" and anything you do is not in compliance. The AHJ could deny
> it based on that alone.
Was that a requirement or a recomendation?
>
> 430.19(F) Cord-and-Plug-Connected Motors. For a
> cord-and-plug-connected motor, a horsepower-rated attachment plug and
> receptacle having ratings no less than the motor ratings shall be
> permitted to serve as the disconnecting means for other than a Design
> E motor and for a Design E motor rated 2 hp or less. For a Design E
> motor rated more than 2 hp, an attachment plug and receptacle used as
> the disconnecting means shall have a horsepower rating not less than
> 1.4 times the motor rating. A horsepower-rated attachment plug and
> receptacle shall not be required for a cord-and-plug-connected
> appliance in accordance with 422.32, a room air conditioner in
> accordance with 440.63, or a portable motor rated 1/3 hp or less.
I understand this in a dedicated circuit. I guess that my question would be
can you even declare a dedicated circuit that terminates with an outlet in a
residence. His best bet would be to ask his building inspector as that is
the man with the final word.
Douglas Miller
>Would it be necessary to go to 4?
Yes, if you want to be legal and safe.
>Could I use 6 instead?
Not if you want to be legal and safe.
Regards,
Doug Miller
--
Real email address is alphageek /at/ milmac /dot/ com
Tom Horne
Doug
Would you please share on what you are basing that position. Is it the
CEC?
--
Tom
Tom Horne
>
> I can't find anything in the code to indicate the rules are different
> for circuits with dedicated motor loads and receptacles. 210
> specifically states it does not apply to motor branch circuits. 430
> gives requirements for the plug and receptacle; they must be HP rated.
> If anyone has code references that say the motor rules don't apply,
> please post 'em; I'm no expert here and always looking to learn...
>
> Bottom line on this is the compressor manual specifically states that
> it is to be permanently wired, and is a "fixed" unit. Since it is
> being installed in vioaltion of it's instructions, it's no longer
> "listed" and anything you do is not in compliance. The AHJ could deny
> it based on that alone.
>
> 430.19(F) Cord-and-Plug-Connected Motors. For a
> cord-and-plug-connected motor, a horsepower-rated attachment plug and
> receptacle having ratings no less than the motor ratings shall be
> permitted to serve as the disconnecting means for other than a Design
> E motor and for a Design E motor rated 2 hp or less. For a Design E
> motor rated more than 2 hp, an attachment plug and receptacle used as
> the disconnecting means shall have a horsepower rating not less than
> 1.4 times the motor rating. A horsepower-rated attachment plug and
> receptacle shall not be required for a cord-and-plug-connected
> appliance in accordance with 422.32, a room air conditioner in
> accordance with 440.63, or a portable motor rated 1/3 hp or less.
One thing that you may have missed is the code only requires you to obey
manufacturers instructions that are "included in the listing or
labeling." An example of included instructions are the note on a panel
label that says unused buss bar openings may be used to terminate up to
three (for example) equipment grounding conductors. Terminate four EGCs
and you are in violation of the listing or labeling. The packaging
includes a manufacturers instruction sheet that says USE ONLY ORIGINAL
MANUFACTURERS BREAKERS. Since that instruction is not on the label that
bares the laboratory listing mark and is not included as an entry on the
laboratory listing document it is not enforceable. If the code allows
the motor in question to be cord and plug connected than the
manufacturers unlabeled instruction manual does not change that.
--
Tom
roydan tomlinson
capability instead of a "Romex" style of cable.
When I check the table 310.16 and 310.17 tables in the NEC I see quite a bit
of difference in the ratings depending on if the cabling is running together
or seperated to allow for better cooling.
--
Just my thoughts.......Roydan
"Larry Caldwell" <lar...@teleport.com> wrote in message
news:MPG.18d569085...@news.earthlink.net...
Douglas Miller
>Douglas Miller wrote:
>> In article <u8Taa.432267$Yo4.15...@news1.calgary.shaw.ca>, "Daniel"
> <Spammersshou...@seriously.com> wrote:
>>
>>>Would it be necessary to go to 4?
>>
>>
>> Yes, if you want to be legal and safe.
>>
>>
>>>Could I use 6 instead?
>>
>>
>> Not if you want to be legal and safe.
>>
>Would you please share on what you are basing that position. Is it the
>CEC?
US NEC. I don't have a copy handy right now, so I'm going from memory and may
be mistaken, but I'm pretty sure #6 isn't approved for 60A.
Doug Winterburn
> US NEC. I don't have a copy handy right now, so I'm going from memory and may
> be mistaken, but I'm pretty sure #6 isn't approved for 60A.
Correct, the ampacity for #6 in other than open air is 55 amps.
-Doug
"There is nothing lower than the human race....Except the French."
--Mark Twain
... ...
Re: installing 220V outlet for air compressor
Group: alt.home.repair Date: Sat, Mar 8, 2003, 9:29pm (EST-1) From:
matt@*woodwork*worzala.com (Matt W.)
there to prevent you from overloading the circuit and generally if you
have #14 wire it is fused at 15 amps and 12 is fused at 20 amps, but
that is not the whole story.
ampacity of a conductor must not be less than the rating of the
overcurrent device protecting that conductor."
The size of the wire is what determines the size of the breaker. Period.
Of course you must choose the wire sixe that matches the overall current
capacity you need.
with how much current a circuit can carry. For short distances #12 will
carry 50 amps. But don't try it with a #12 100 ft extension cord. This
is due to the resistance of the wire, the longer the wire the more
resistance.
longer runs. But to say that length has MORE to do with ampacity than
cross- sectional area (size) is ludicrous. And dangerous.
the cross sectional area of solid wire is greater than stranded. hence
less resistance.
Ampacities of Insulated Conductors
There is NO specification for a different ampacity rating using a solid
or stranded wire. They have the same cross-sectional area and the same
ampacity rating.
--
Matt W.
Sent Using M2, Opera's revolutionary e-mail client
http://www.opera.com/m2
Maybe we should try the 2002 NEC seeing as that is the one in use at
this time.
BTW how come nobody mentioned matching the tepmerature rating of the
conductors insulation to that of the breaker???? I think that one came
out in the 1999 NEC .
Tom Horne
> In article <3E6CEBEE...@takomaparkfire.org>, Tom Horne <postm...@takomaparkfire.org> wrote:
>
>>Douglas Miller wrote:
>>
>>>In article <u8Taa.432267$Yo4.15...@news1.calgary.shaw.ca>, "Daniel"
>>
>><Spammersshou...@seriously.com> wrote:
>>
>>>>Would it be necessary to go to 4?
>>>
>>>
>>>Yes, if you want to be legal and safe.
>>>
>>>
>>>
>>>>Could I use 6 instead?
>>>
>>>
>>>Not if you want to be legal and safe.
>>>
>>
>
>>Would you please share on what you are basing that position. Is it the
>>CEC?
>
>
> US NEC. I don't have a copy handy right now, so I'm going from memory and may
> be mistaken, but I'm pretty sure #6 isn't approved for 60A.
>
> Regards,
> Doug Miller
> --
> Real email address is alphageek /at/ milmac /dot/ com
>
Even in type NM cable #6 AWG THHN can carry 55 amps. In other wiring
methods it is good to 65 amperes. When the ampacity of the wire does
not correspond to the rating of a standard circuit breaker the US NEC
specifically permits the use of the next higher standard size in
breakers up to 800 amperes.
--
Tom
ATP
Has Table 310-16 changed in the last ten years? #6 copper THHN is good for
75 amperes in a cable assembly. #8 copper THHN is rated at 55 amperes, which
would allow a 60 amp breaker as the next standard size. From my 1993 NEC
Handbook. Here's a chart from a wire manufacturer on the net:
http://www.awcwire.com/pdf/CT-B5-THHN.pdf
ATP
> Please note: The following comments do NOT apply to standard general
> purpose circuits.> news:v6mgcuq...@corp.supernews.com...
>> I am not disputing your right (obligation?) to put a breaker on that
>> will not cause nuisance trips; only that you also have to use wire
>> sized to the breaker.
>> Nothing in your long quote allowed smaller wire.
>
> Wade, you are arguing against a point that is common knowledge to
> _anyone_ who knows motor wiring. Get your (2002 NEC) code book and
> follow along if you can. A 1999 or 1996 NEC code book will suffice,
> only the referenced Section
> numbers will be different, and the wording slightly different. The
> principles are the same.
>
> See Table 310.16. See the asterisk (*) next to the 14, 12, and 10
> gauge wires? The asterisk at the bottom of the page says to "see
> 240.4(D)". What does Section 240.4(D) say? :
>
> 240.4 Protection of Conductors.
>
> 240.4(D) Small Conductors: "UNLESS SPECIFICALLY PERMITTED IN 240.4(E)
> THROUGH (G), the overcurrent protection shall not exceed 15 amperes
> for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG
> copper........and so on."
>
> Now look at 240.4(G):
>
> 240.4(G) Overcurrent Protection for Specific Conductor Applications.
> "Overcurrent protection for the specific conductors SHALL BE
> PERMITTED as referenced in Table 240.4(G)."
>
> Look at Table 240.4(G) Specific Conductor Applications. You will see
> MOTORS listed in this table (Article 430, Parts III, IV, V, VI, VII)
>
> GOT IT so far?
>
> Look at Article 430, Part IV. Motor Branch-Circuit Short-Circuit and
> Ground-Fault Protection
>
> 430.52 Rating or Setting for Individual Motor Circuit.
>
> 430(A) General. "The motor branch-circuit short-citrcuit and
> ground-fault protective device SHALL comply with 430.52(B) and either
> 430.52(C) or (D), as applicable."
>
> What does Section 430.52(B) say? "The motor branch-circuit
> short-circuit and ground fault protective device shall be capable of
> carrying the starting current of the motor."
>
> Section 430.52(C) Rating or setting.
>
> Section 430.52(C)(1) "In Accordance with Table 430.52. A protective
> device that has a rating or setting not exceeding the value
> calculated according to the values given in Table 430.52 shall be
> used...........and so on"
>
> What does Table 430.52 (Maximum Rating or setting of Motor
> branch-Circuit Short-Circuit and Ground-Fault Protective Devices)
> say? For a single-phase motor, the percentage of Full-Load Current
> for a Nontime Delay Fuse is 300%, for a Dual Element (Time-Delay)
> Fuse, 175%, and 250% for an Inverse Time Breaker.
>
> What does all this mean? As an example, lets say that the OP's
> compressor motor is really a 3 HP motor (we know that the _developed_
> HP is 7HP, which cannot be used for the calculation.)
>
> Looking at Table 430.148 (Full-Load Currents in Amperes, Single Phase
> Alternating-Current Motors), one sees that the FLA for a 3 HP, 230
> volt, single-phase motor is 17 amps. Taking 125% of 17 amps (from
> 430.22) one gets 21.25 amps. The _minimum_ ampacity of the
> _conductors_ MUST_ be 21.25 amps. Looking at Table 310.16 again, and
> assuming that romex is used (reading from the 60 degree C column per
> 334.80), one determines that a #12 romex is required (good for 25
> amps in this case.)
>
> Now figure the fuse/breaker size. For a nontime-delay fuse: 17amps x
> 300% = 51 amps. Since 430.52(C)(1) Exception No. 1 permits going to
> the next standard size fuse, per 240.6, up to a 60 amp nontime-delay
> fuse can be used on the #12 wire for the motor.
>
> For a time-delay fuse: 17amps x 175% = 29.75amps, up to a 30 amp
> time-delay fuse can be used on the #12 wire for the motor.
>
> For an inverse-time breaker: 17 amps x 250% = 42.5amps, up to a 45amp
> inverse-time breaker can be used on the #12 wire for the motor.
>
>
> Good wiring practice is to use the _lowest_ fuse/breaker that will
> allow the motor to start. That is why I recommended to the OP in
> another post that the usual practice is to install a fused disconnect
> at the compressor, so that lowest possible fuse can be used. In this
> 3HP example, I would start with a 20 amp time-delay fuse.........if
> that didn't hold, try a 25amp TD, and so on.........NOT to exceed a
> 30 amp TD fuse, as calculated.
>
> As far as OVERLOAD protection for the motor, the motor has a built-in
> thermal overload protector.........otherwise one would also have to
> provide a motor starter with correctly sized overloads.
>
> Sorry about the long post, but sometimes there is more to electrical
> work than a roll of baling wire and a set of Kleins.
Most of us who have passed a licensing exam are aware of the allowances for
motor circuits, but consider the following scenario John presents:
"The
reason I use a 30 amp breaker is if I am running the table saw under
a full load and the compressor kicks in it will not trip the breaker
do to the current surge when the compressor starts. A safety factor
when running the saw."
Right there you do not have a dedicated circuit. In addition, his
explanation of conductor sizing as being dependent on length was incorrect
except for the observation that small lengths of small gauge wire will not
create large voltage drops.
Tom Horne
>>Even in type NM cable #6 AWG THHN can carry 55 amps. In other wiring
>>methods it is good to 65 amperes. When the ampacity of the wire does
>>not correspond to the rating of a standard circuit breaker the US NEC
>>specifically permits the use of the next higher standard size in
>>breakers up to 800 amperes.
>
>
> Has Table 310-16 changed in the last ten years? #6 copper THHN is good for
> 75 amperes in a cable assembly. #8 copper THHN is rated at 55 amperes, which
> would allow a 60 amp breaker as the next standard size. From my 1993 NEC
> Handbook. Here's a chart from a wire manufacturer on the net:
> http://www.awcwire.com/pdf/CT-B5-THHN.pdf
>
>
ATP
Unless you have a source for breakers that include 90° Centigrade
terminations you cannot use the 90° column of the table as anything but
a starting point for derating the conductors for ambient temperature or
the number of conductors in a raceway. The code requires the use of the
60° column for the ampacity of the conductors in type NM cable.
Let me repeat that unless the terminations at both ends of the conductor
are listed for use at 90° C you cannot use the 90° ampacity for
selecting the Over Current Protective Device.
--
Tom
ATP
True. I must have been a little too far into my cardboard box of wine :-)
Although it's ironic that when you apply the exceptions for residential
services, you'd be in the 90 C column if the service was ever maxed out.
Mr G H Ireland
<jo...@pldi.net> wrote:
> The more resistance the more voltage drop between the
> source and the load, The more voltage drop the more watts dissipated
> burns up. So the bottom line is really the length of the run.
Not quite. A given length of wire will drop a certain voltage. A longer one
will drop more, but the original length will still drop the same as before
and will warm up the same, whether at the end of it is a motor, etc., or
some more wire.
Of course,the motor at the end of the wire will only get the power supply
voltage less the voltage drop in the wire and that is why a longer wire
requires a bigger wire diameter, not the heating of the wire, unless the
wire is wound up on a drum or such.
G.H.Ireland.
--
__ __ __ __ __ ___ _____________________________________________
|__||__)/ __/ \|\ ||_ | /
| || \\__/\__/| \||__ | /...Internet access for all Acorn RISC machines
___________________________/ ig...@argonet.co.uk
Bruce
The answer is very simple.
1. Go the the local Electrical inspector.
2. Pay the money for the building permit. In my area $10.00.
3. Ask the inspector what is acceptable in the area.
OR "CALL A lisensed Electrical Contractor to do the work
!!!!!!!!!!!!!!!!!!!!!!!!!!!
Why do so many people take a chance with something that can Burn down
your shop/house or KILL you in the blink of an eye?
I am probably wasting me time. I have made comments about this for a
long time, but there are tons of threads out there - all about 220V
circuits. Let the experts do it.
"Just one man's opinion."
The Other Bruce
Tom Horne <postm...@takomaparkfire.org> wrote in message news:<3E6CF37C...@takomaparkfire.org>...
Bainsville
doing it.
CALL A licensed Electrical Contractor
"Bruce" <MHWood...@hotmail.com> wrote in message
news:620c3eb4.03031...@posting.google.com...
John Rowlands
will find problems and situations that his knowlege will be insufficient
for, and you know what, he will ask a question. It may be in the form of
asking a fellow electrician, or in the form of consulting his code book and
textbooks, but he wil not profess to know everything. That would be
arrogant and even more dangerous than someone who will ask a question.
I can wire a house, I have done it in the past and am doing it now. I'm not
a licensed electrician and I do ask questions about stuff that I have not
done before. Electricity is simple if you understand the basics. Alot of
questions involve not the basic theory of electricity but involves specific
details.
If we were to follow your logic then none of the astronauts in the shuttle
should have been there. Why? Because they consult a manual for all of the
procedures that they accomplish. Certainly you would think that if they have
to ask a question or consult a manual then they shouldn't be flying that
shuttle.
--
Rick Rowlands
Tod Engine Foundation
34" x 68" x 60" Cross Compound Stationary Steam Engine
Historic Mechanical and Materials Engineering Landmark
Youngstown, OH
www.todengine.org
"Bainsville" <bainsv...@hotmail.com> wrote in message
news:qblca.6427$4q6.9...@news20.bellglobal.com...
volts500
"John Rowlands" <JROW...@neo.rr.com> wrote in message
news:7Hrca.68916$jP2.10...@twister.neo.rr.com...
> Well I wholeheartedly disagree with that one. Even a licensed electrician
> will find problems and situations that his knowlege will be insufficient
> for, and you know what, he will ask a question. It may be in the form of
> asking a fellow electrician, or in the form of consulting his code book
and
> textbooks, but he wil not profess to know everything. That would be
> arrogant and even more dangerous than someone who will ask a question.
>
> I can wire a house, I have done it in the past and am doing it now. I'm
not
> a licensed electrician and I do ask questions about stuff that I have not
> done before. Electricity is simple if you understand the basics. Alot of
> questions involve not the basic theory of electricity but involves
specific
> details.
>
> If we were to follow your logic then none of the astronauts in the shuttle
> should have been there. Why? Because they consult a manual for all of the
> procedures that they accomplish. Certainly you would think that if they
have
> to ask a question or consult a manual then they shouldn't be flying that
> shuttle.
>
>
> --
> Rick Rowlands
Perhaps you didn't read the RE: "Help with install of 30a breaker" thread
in alt.home.repair because of the idiot crossposting OP? The OP of this
thread is the same moron who started that thread. He wanted to install a
(bolt-on) Pushmatic breaker (obviously for the compressor) in his main panel
that doesn't have a disconnect. He doesn't have the skill or knowledge to
work it hot..........so after being told call the power company to let them
know he was pulling the meter (or let them do it) to de-energize the panel,
he suggested that he'll just wait for a power outage. Still think he should
be doing electrical work? NOT!
Jim Stewart
Sounds like Darwin at work to me.
Bruce
manufacturer says to "Hard Wire" it? Mifght be the only SAFE way to do
it - in their mind. HMMMMMMMMMMMMMMMMMMMMMM!
The Other Burce
"Bainsville" <bainsv...@hotmail.com> wrote in message news:<qblca.6427$4q6.9...@news20.bellglobal.com>...