Why no neutral with 220V wiring?
Gary Watts
ground. Yet, in the same wiring, 220V applications have 2 hots, a ground a
and no netural. Isn't this the same safety issue?
Gary
bruno bienenfeld
In USA power system is different than European.Without going into
technical details it is " Y " vs " Delta " power configuration.
If you need more elaborate info e-mail.
Regards
Bruno AA6AD
Mike J Oropeza
>
> Obviously a regular 120V single phase home wiring has a hot, netural and a
> ground. Yet, in the same wiring, 220V applications have 2 hots, a ground a
> and no netural. Isn't this the same safety issue?
It is safe without a neutral. Each hot is 120V that is out-of-phase by
180 degrees. If one leg is positive, the other is negative, and the
voltage is the difference between the two (i.e. 120 - -120 = 240). That
is, 240V is present only when measured against both hots. Either hot
provides 120V to ground or neutral (which are usually electrically
equivalent, but have different purposes) (i.e. 120 - 0 = 120). The
ground is provided so that if voltage is applied to the chassis of a
device, electricity will flow to earth through the ground instead of the
person touching the device. Neutral (or common) is provided to provide a
flow to earth for operation of the device.
--
Mike J Oropeza
Those who hear not the music, think the dancers mad ~{';'}~
Greg Fretwell
is a "pure" 240v load there would be no purpose for the neutral but you
still need the Equipment Grounding Conductor for safety reasons.
There was an aberration in the National Electric Code since the copper
rationing of WWII that allowed ranges and driers to share the ground and
neutral only providing a 3 prong plug even if they had a neutral load.
The NFPA finally figured out the war was over in 1996 and made that
exception go away. Now you need a 4 prong plug on new construction and
renovation.
BTW some local codes have required a 4 wire feeder to these receptacles
for years so this might not be the problem it seems. The ground went to
the box with the white wire going to the 3d prong of the receptacle. If
you have 10/3 or 8/3 with ground the receptacle swap is easy.
Greg gwa...@cv.hp.com (Gary Watts) wrote:
>
>Obviously a regular 120V single phase home wiring has a hot, netural and
a
>ground. Yet, in the same wiring, 220V applications have 2 hots, a
ground a
>and no netural. Isn't this the same safety issue?
>
>Gary
Sam Goldwasser
> Obviously a regular 120V single phase home wiring has a hot, netural and a
> ground. Yet, in the same wiring, 220V applications have 2 hots, a ground a
> and no netural. Isn't this the same safety issue?
No, it still has the Ground. If the appliance has no need of 120, what exactly
would you propose it do with the Neutral? :-)
--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Sam's Laser FAQ: http://www.misty.com/~don/lasersam.html
Sharon & Joe L.
Gary Watts wrote in message <734c6d$rqg$1...@ocean.cup.hp.com>...
>Obviously a regular 120V single phase home wiring has a hot, netural and a
>ground. Yet, in the same wiring, 220V applications have 2 hots, a ground a
>and no netural. Isn't this the same safety issue?
>
has when the white neutral is tied to the same bar in the service pannel?
(or at least it seems so.) Not knocking anyone or any code requirements,
just wanting to know the principle behind it. Thanks, Joe
Robert Hancock
current that does not normally carry current itself. If you used the same
wire for the neutral and case ground then if the neutral became disconnected
and you turned the device on then the case would become live.
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from rhan...@nospamsk.sympatico.ca
Home Page: http://www.geocities.com/TimesSquare/Arcade/9967/
Sharon & Joe L. wrote in message <3655e...@tornado.tcccom.net>...
JCoggins
(cracked anyway from all the heat) suddenly fails and makes the metal
enclosure electrically hot.
With no ground wire, current has to travel whatever path there is: you,
floor, dirt, walls. And there may so much resistance that there's not enough
current to trip the breaker. A steady one amp will kill you. A few more
might start a fire, whether you're there or not.
With a ground wire connected to the enclosure, the fault current finds a low
resistance path back to the panel, where it should trip the breaker.
With one course, you might be lucky. With the other, you planned ahead.
lang...@teleport.com
>>Obviously a regular 120V single phase home wiring has a hot, netural and a
>>ground. Yet, in the same wiring, 220V applications have 2 hots, a ground a
>>and no netural. Isn't this the same safety issue?
Every safe circuit has two wires that carry the current (one for
supply), one for return), and one that caries nothing unless there is
a fault.
In 110V, one of the current carrying wires is hot (110V) the other is
neutral.
In 220V, one of the current carrying wires is hot (+110V), the other
is hot, at opposite polarity (-110V).
Both use the bare ground to carry current away from any housing or
other metal object that a damaged hot wire might contact.
On Fri, 20 Nov 1998 16:02:44 -0600, "Sharon & Joe L."
<sha...@nconnect.net> wrote:
>Something I've always wondered about is what purpose the bare copper wire
>has when the white neutral is tied to the same bar in the service pannel?
>(or at least it seems so.) Not knocking anyone or any code requirements,
>just wanting to know the principle behind it. Thanks, Joe
Neutral carries current back to the ground bar in normal use, ground
carries current only when there is a fault such as a short between the
hot wire and a grounded housing.
Think of the cable as a highway. The southbound lanes take cars to
their destinations, the northbound lanes take them back home. The
frontage road is not used, unless there is an emergency (such as an
accident that stops traffic), when it is used to get an ambulance to
the scene.
--
Bennet K. Langlotz
lang...@teleport.com
danh...@infonet.isl.net
>Obviously a regular 120V single phase home wiring has a hot, netural and a
>ground. Yet, in the same wiring, 220V applications have 2 hots, a ground a
>and no netural. Isn't this the same safety issue?
The same issue as what?? Properly installed and used, 240V is just as
safe as 120V.
Dan Hicks
Hey!! My advice is free -- take it for what it's worth!
http://www.millcomm.com/~danhicks
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Robert Hancock
volt circuit, it is no more dangerous than 120. Both lines are 120 volts
above ground so if you are grounded and grab a conductor it is the same as
if you grabbed the hot in a 120 volt circuit. Granted that's not very good
for you either :-)
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from rhan...@nospamsk.sympatico.ca
Home Page: http://www.geocities.com/TimesSquare/Arcade/9967/
danh...@infonet.isl.net wrote in message
<36562...@maxim.newsfeeds.com>...
dslosty
>On a 240v circuit you only need a neutral if there are 120v loads. If it
>is a "pure" 240v load there would be no purpose for the neutral but you
>still need the Equipment Grounding Conductor for safety reasons.
>There was an aberration in the National Electric Code since the copper
>rationing of WWII that allowed ranges and driers to share the ground and
>neutral only providing a 3 prong plug even if they had a neutral load.
>The NFPA finally figured out the war was over in 1996 and made that
>exception go away. Now you need a 4 prong plug on new construction and
>renovation.
>BTW some local codes have required a 4 wire feeder to these receptacles
>for years so this might not be the problem it seems. The ground went to
>the box with the white wire going to the 3d prong of the receptacle. If
>you have 10/3 or 8/3 with ground the receptacle swap is easy.
>
>
> Greg gwa...@cv.hp.com (Gary Watts) wrote:
In terms of using a 4 wire dryer or range plug, I agree that the new
code does require separate neutral and ground. However, I wonder at
the practicality.
After installing several appliances this year, I noticed that they
all came thru from the manufacturer with with the neutral and the
ground lugs strapped together - generally with a small buss bar.
Obviously, this buss bar has to be removed to separate neutral and
ground - few people are doing this. Thus the chassis is connected
to both neutral and ground.
In my, probably incorrect opinion, not removing the buss is good.
It provides a redundant path for fault currents. However, it does
violate the NEC regarding not having neutral and ground connected
together outside of the service entrance. Seems to me that the
appliance industry is in flux over this issue.
Doug
"Use it up, wear it out. Make it do, or do without."
Remove the "_" in my return address to reply.
AlarmHome
Dryer heating element is 240v fed by 2 insulated legs...timer,buzzer,etc are
probably 120v with return feed through the neutral conductor. If the strap
or buss is left in place this will place current flow in parallel with the
neutral wire. Thus the *fatal* possibility exists that someone downstream
could touch the bare ground and be zapped.
Anyone?
Cheers....Mike S.
danh...@infonet.isl.net
>My personal opinion....
>
>Dryer heating element is 240v fed by 2 insulated legs...timer,buzzer,etc are
>probably 120v with return feed through the neutral conductor. If the strap
>or buss is left in place this will place current flow in parallel with the
>neutral wire. Thus the *fatal* possibility exists that someone downstream
>could touch the bare ground and be zapped.
With the strap in place, there's the chance that they can touch the CASE
of the dryer and get zapped, even though the dryer itself doesn't have an
internal short. This is doubly true since many dryer outlets are miswired
to one extent or another, missing either ground or neutral connection.
The strap should ONLY be used if it is necessary to use a 3-prong pigtail
due to existing house wiring, and that should only be done if it is quite
impractical to replace the wiring.
Tom Gauldin
there is less temptation to tap one leg and the neutral for a "cheap"
120v connection. Where needed, as in an oven's light, the neutral is
required for just that purpose.
--
Tom Gauldin, Raleigh NC scou...@mindspring.com
ftp://ftp.mindspring.com/pub/users/scoundrl/home.htm
Here's to the land of the Longleaf Pine,
The Summerland, where the sun doth shine.
Where the weak grow strong, and the strong grow great,
Here's to Downhome, the Old North State.
----------------------------------------------------------------------
-------------------
Sam Goldwasser wrote in message ...
>In article <734c6d$rqg$1...@ocean.cup.hp.com> gwa...@cv.hp.com (Gary
Watts) writes:
>
>> Obviously a regular 120V single phase home wiring has a hot,
netural and a
>> ground. Yet, in the same wiring, 220V applications have 2 hots,
a ground a
>> and no netural. Isn't this the same safety issue?
>
Tom Gauldin
>>>
>>Something I've always wondered about is what purpose the bare copper
wire
>>has when the white neutral is tied to the same bar in the service
pannel?
>>(or at least it seems so.) Not knocking anyone or any code
requirements,
>>just wanting to know the principle behind it. Thanks, Joe
>>
The neutral is "defined" as a return leg for current to the
transformer. Neutral wires are not supposed to be switched, for
instance, but it has been known to happen, particularly in more
confusing circuits like 3-way and 4-way lighting. When a switch
regulates something, such as a light, via the neutral wire, the light
fixture MAY be accidentally "hot" from contact with either wire, and
not trip the breaker. The bare ground, by definition and use, may
NEVER be broken, thus insuring that anything it touches must be
grounded.
JCoggins
Tom Gauldin wrote in message <737dr6$bje$1...@camel25.mindspring.com>...
Dan Canister
>In USA power system is different than European.Without going into
>technical details it is " Y " vs " Delta " power configuration.
H'mm, I don't think this has anything to do with the original question, but
if you are implying that a delta connection is more safe, I don't believe
that to be true. Your talking three phase verses two.
Greg Fretwell
pole (osing one primary phase and ground). but on our side it is just a
center tapped 240v secondary with the tap grounded. I think they give you
2 phases of a "floating delta" in europe with no ground reference.
Theoretically you can touch the hot and be a "bird on a wire" or so I
understand. There are apllications where you can have ungrounded delta
here but you need some extra stuff and AHJ approval.
Greg
JS
or grey.The bare wire is connected to the metal in the case or
structure of appliances and electrical equipment. Its's purpose is to
serve as a low impedance path back to the transformer, should the hot
wire somehow touch the case or equipment. The current flow then
returning to the panel, and therefore through the breaker, will trip
the breaker, cutting off current flow. The ground wire is a safety
feature, the neutral is the normal return path for current. The main
panel is the only place they are normally allowed to be tied together.
J
MZ
240v, 1 neutral which is connected to ground at the generating company's
supply, and 1 ground wire which is connected to your house ground rod/water
pipes. You can get 2-phases of hot coming in to your house if you need to
operate some heavy industrial standard equipment which requres 480 v. In
North America you normally have 2-phases of 110 and you try to balance the
load returning on the neutral. In the UK the electricity company distributes
3-phases of 240v to a street, with 1 phase going to 1 house, another to a
neighbour and the third phase going to the other neighbour etc.
MZ
Greg Fretwell wrote in message
<7384ls$1fhq$1...@newssvr03-int.news.prodigy.com>...
Greg Fretwell
I bet that will wake you up in the morning when the shaver drops in the
sink.
Greg
JCoggins
around the shower head. It's used for an inline electric heater -- hot water
on demand. Step in there and turn the water on! Never did understand what
you have to reach out and touch to make the water hotter.
Greg Fretwell wrote in message
<739p1j$1i8q$2...@newssvr03-int.news.prodigy.com>...
Calvin Henry-Cotnam
>After installing several appliances this year, I noticed that they
>all came thru from the manufacturer with with the neutral and the
>ground lugs strapped together - generally with a small buss bar.
>Obviously, this buss bar has to be removed to separate neutral and
>ground - few people are doing this. Thus the chassis is connected
>to both neutral and ground.
>
>In my, probably incorrect opinion, not removing the buss is good.
>It provides a redundant path for fault currents. However, it does
>violate the NEC regarding not having neutral and ground connected
>together outside of the service entrance.
It also provides a redundant path for any 120 V load currents, which
means there will be a voltage drop on the ground conductor between
the service panel and the appliance. Ergo, the chassis of the appliance
will not be at ground potential.
--
Calvin Henry-Cotnam | "The greatest gift interracial couples
DAXaCK associates | and families bestow on society is the
Scarborough, Ontario, Canada | reality of equality."
http://home.ica.net/~calvinhc | -- Candace Mills, Magazine Publisher
----------------------------------------------------------------------------
NOTE: if replying by email, remove the '*' - it's there to block junk email!
dslosty
>In <736d7b$i95$1...@birch.prod.itd.earthlink.net>, "AlarmHome" <Alar...@Zdnetmail.com> writes:
>>My personal opinion....
>>
>>Dryer heating element is 240v fed by 2 insulated legs...timer,buzzer,etc are
>>probably 120v with return feed through the neutral conductor. If the strap
>>or buss is left in place this will place current flow in parallel with the
>>neutral wire. Thus the *fatal* possibility exists that someone downstream
>>could touch the bare ground and be zapped.
>
>With the strap in place, there's the chance that they can touch the CASE
>of the dryer and get zapped, even though the dryer itself doesn't have an
>internal short. This is doubly true since many dryer outlets are miswired
>to one extent or another, missing either ground or neutral connection.
>
>The strap should ONLY be used if it is necessary to use a 3-prong pigtail
>due to existing house wiring, and that should only be done if it is quite
>impractical to replace the wiring.
>
>Dan Hicks
>Hey!! My advice is free -- take it for what it's worth!
>http://www.millcomm.com/~danhicks
>
For an individual to get zapped when a dryer or range chassis is
connected to both neutral and ground, there would have to be a very
large voltage drop or an open wire condition on both the neutral and
the ground wire. Not a likely scenario.
In any event, my main point was that manufacturers are not being too
emphatic about pulling the bussbar. To quote a recent manual that I
have here: "if local codes prohibit grounding through the neutral,
disconnect the factory installed bussbar".
On the other hand, they spent a full page extolling the virtues of the
"anti-tip device".
JCoggins
getting "zapped." Voltage does not kill or start fires; current does, and
it favors small resistances. From V=IR, these often produce small voltage
drops.
dslosty wrote in message <36592dee...@news.pipeline.com>...
Brian Denheyer
> current to trip the breaker. A steady one amp will kill you. A few more
> might start a fire, whether you're there or not.
Actually a steady 200mA will kill you. A very brief 1 A will kill
you, or make you're heart stop or make it do something that isn't good
for you.
Brian
--
Brian Denheyer
bri...@inetarena.com
dslosty
>Have to question the idea that a large voltage drop is a prerequisite for
>getting "zapped." Voltage does not kill or start fires; current does, and
>it favors small resistances. From V=IR, these often produce small voltage
>drops.
>
Death by electrocution can be caused by as little as 1 millamp if it
passes through the heart. However, the human body offers a skin
resistance of several megohms under normal conditions (not including
standing dripping wet on a concrete floor in bare feet - for example).
It does take quite a bit of voltage to push a lethal current thru the
human body. Ever see anyone get electrocuted by touching the output
of a 24 VAC bell transformer, which can put out several amps???
Only once have I seen a house wiring neutral float more than 20 volts
above ground. In that case, there was a corroded ground connection
at the service entrance and the house wiring load was severely
unbalanced between phases.
MZ
MZ
BillyFish
line with the 120 volt phases at 180 degrees to one another. There is a
neutral that allows you to run unbalanced loads. If the loads were balanced
all the time, you would not need the third wire.
Bill
JCoggins
current), then 3000 volts is the critical threshhold. Fact is, people die on
a lot less.
Trouble is, the 3,000,000 ohm resistance is very misleading. Make it 100
million or more. If you touched something and put yourself in parallel with
a 1 ohm fault path, the net resistance will always be less than 1 ohm! So
if 3000 volts is needed to force a milliamp into the heart, does that mean
you're safe at anything under 3000 amps?
dslosty wrote in message <365a83eb...@news.pipeline.com>...
nigel_...@my-dejanews.com
gwa...@cv.hp.com (Gary Watts) wrote:
> Obviously a regular 120V single phase home wiring has a hot, netural and a
> ground. Yet, in the same wiring, 220V applications have 2 hots, a ground a
> and no netural. Isn't this the same safety issue?
>
Gary:
If you're talking about the service entrance, then you get 2 hots and a
neutral, not a ground. The ground and neutral should be bonded at the service
entrance. The ground is then run separately from the neutral to all grounded
outlets.
Now, to what was probably your question, before the 1996 NEC electric dryers
and ranges were allowed to use 2 hots and the NEUTRAL, with the neutral being
used as the ground.
After the 1996, this practice has been disalowed. You must run 4 wires for
these. The reason for a neutral is because there is usually control
circuitry in the appliances (for clock, timer, thermostat, etc.) that runs
off 120 Volts, so there is current on the neutral.
Motors on the other hand are allowed to have 2 hots and a ground, with the
ground never conducting except when a fault occurs. So, in my home, my 220
Volt dryer should be 4 wires, but my 220 Volt table saw should only have 3.
I hope this helps,
Nigel
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