Running electrical wire through PVC pipe
hibb
basement up to the second floor to make it easier to run more cable
(data cable, TV Coax and such) up there should I need to in the
future. I thought about just running the electric wire in the pipe too
but I though I read where someone on this group mentioned to not run
electric wire through PVC.
Did I misread something or is that true? It if is true, what is the
problem with it.
Sure seems like it would be easier to run wire in future projects. But
then if I do the job right, the won't be much reason to run more wire
for a long, long time anyway.
Thanks, David
mike
Google shop PVC conduit.
A separate issue is whether AC current might pose interference issues
for various other types of lines.
hibb
Thanks, Mike.
I just googled on the issue I posted here and it looks like there is a
heat issue if electric wires are enclosed in a conduit.
I really can't see me ever having to run more electric wire up there
as long as I live here. But I will surely run a conduit for the other
types of wire.
Thanks, David
JIMMIE
pvc electrical conduit is fine
Jimmie
Wayne Whitney
> I was going to install 1 1/2 inch PVC pipe in the wall from the
> basement up to the second floor to make it easier to run more cable
> (data cable, TV Coax and such) up there should I need to in the
> future. I thought about just running the electric wire in the pipe too
> but I though I read where someone on this group mentioned to not run
> electric wire through PVC.
>
> Did I misread something or is that true? It if is true, what is the
> problem with it.
OK, here's the scoop:
If your electrical wiring is of cable type (NM, UF, MC, or AC), then
you can run it through any kind of pipe or tube as just a sleeve. The
sleeve is not part of the electrical system, it is there just to make
fishing easier.
If you want to run individual electrical wires (like THHN-2), then for
PVC you must use the grey electrical conduit. You also need a
complete conduit system, i.e. the conduit must start and end at
electrical boxes (where you could switch over to other wiring
methods).
In terms of overheating, you need to watch how many current carrying
conductors (CCCs) you run together for a significant length. If you
have too many together you have to "derate" each conductor so that it
carries less current, or alternatively upsize the conductor for a
given current. The rules are complicated, and derating potentially
starts at 4 CCCs. However, for NM cable in #14 and #12 sizes, you can
run up to 9 CCCs and still maintain the usual 15A and 20A capacities,
respectively.
As far as mixing electrical and data wiring, it is best not to for
reasons such as interference, although it may be allowed. You'd have
to check the NEC for the details. I do know that when it is allowed,
and you are using individual electrical wires, then the data wiring
must have an insulation rating at least as high as the voltage of the
electrical system.
Cheers,
Wayne
mike
>
> You can find any answer you want on a google search, most wrong.
> The reality is the (heat) derating for wire in conduit is exactly the
> same as it is for wire in a cable.
> - Show quoted text -
So it's mostly wrong that PVC conduit is available on Google Shopping?
Lp1331 1p1331
conduit at HD, it was cosiderably cheaper than the same size sched. 40
water pipe. One would think it would be the other way around. YMMV.
Larry
Mikepier
In short., you shouldn't run low voltage and high voltage cable in the
same pipe.
If you can run 2 seperate pipes for each, then your fine.
mm
wrote:
>I was going to install 1 1/2 inch PVC pipe in the wall from the
>basement up to the second floor to make it easier to run more cable
>(data cable, TV Coax and such)
Don't just run the pipe. Inside it run some nylon string or something
strong, substantially longer than the pipe, so you can pull new wires
through easily. And leave it there even when you think you are done.
I would like to run one more wire to my attic, but it's too hard to
get it through hole in the plywood between floors one and two.
LouB
Good fishing line would do the trick.
Good tip.
Art Todesco
rope that they sell at Lowe's or HD or
at electrical places. And, when pulling
a new wire into the conduit, pull an
extra piece of the nylon stuff for the
next time.
LouB
Good point.
What is nylon pull rope? I guess I wil visit the local(1/2 mile away) HD
N8N
> Art Todesco wrote:
> > On 2/25/2010 6:42 AM, LouB wrote:
> >> mm wrote:
> >>> wrote:
>
> >>>> I was going to install 1 1/2 inch PVC pipe in the wall from the
> >>>> basement up to the second floor to make it easier to run more cable
> >>>> (data cable, TV Coax and such)
>
> >>> Don't just run the pipe. Inside it run some nylon string or something
> >>> strong, substantially longer than the pipe, so you can pull new wires
> >>> through easily. And leave it there even when you think you are done.
> >>> I would like to run one more wire to my attic, but it's too hard to
> >>> get it through hole in the plywood between floors one and two.
>
> >> Good fishing line would do the trick.
> >> Good tip.
> > Actually, get some of that nylon pull rope that they sell at Lowe's or
> > HD or at electrical places. And, when pulling a new wire into the
> > conduit, pull an extra piece of the nylon stuff for the next time.
>
> Good point.
> What is nylon pull rope? I guess I wil visit the local(1/2 mile away) HD
they probably won't have it at HD, you will likely have to go to a
real electrical supply house
nate
hibb
I will be stopping by Home Despot today and pick up some pipe and see
what kind of fitting I can use in this project.
Thanks, David
Jon Danniken
Electrical conduit doesn't have to hold water at a particular temperature
and pressure. It also doesn't have to be capable of housing potable water.
Hence, it is cheaper.
Jon
Bob F
I had good luck using a plumbing snake to go down from my attic to basement (2
story house) alongside the plumbing vent. By turning the snake back and forth
when it stops going down, the end moved enough to find a clear path. If there is
a path, you might be able to find it this way.
LouB
Wow 59.90 for 6500 feet of the stuff.
Fishing line is a lot cheaper if you get lite stuff.
I could see where a pro could use it.
Lou
mm
wrote:
Ahl, yeah, I stared to say substantially more than 2 times as long as
the pipe but couldn't quite remember why. Make the pull string that
long and attach what is pulled in the middle, and there will still be
some of it sticking out both ends when he is done pulling. He can run
the same string back and forth, back and forth, pulling in either
direction.
I don't think fishing line is going to be easy to attach anything to,
especially compared to nylon string, but he may know more abou
tfishing line than I do.
Pete C.
Realize that that line isn't really rated for pulling wire, it's
intended to be cheap and light weight to install in conduit and then use
to pull actual rope into the conduit to pull the wires. That "Powr-Fish"
relates to it's intended installation method where it is blown through
the conduit by air pressure attached to a little foam plug piston.
The pull line has far more stretch and much lower breaking strength than
rope. It will work ok for pulling light stuff like coax and cat5 cable.
There is a version of it that is a flat woven tape which is marked off
in feet along it's length so you can blow it through an unknown length
of conduit and get a measurement to order wire.
cl...@snyder.on.ca
PolyTwine is best. Doesn't deteriorate and is easy to find
The Daring Dufas
There are small rolls at the big box stores in the electrical wiring
section.
TDD
N8N
wrote:
> N8N wrote:
> > On Feb 25, 8:38 am, LouB <L...@invalid.invalid> wrote:
> >> Art Todesco wrote:
> >>> On 2/25/2010 6:42 AM, LouB wrote:
> >>>> mm wrote:
> >>>>> On Wed, 24 Feb 2010 10:34:07 -0800 (PST), hibb <ShyPic...@aol.com>
> >>>>> wrote:
> >>>>>> I was going to install 1 1/2 inch PVC pipe in the wall from the
> >>>>>> basement up to the second floor to make it easier to run more cable
> >>>>>> (data cable, TV Coax and such)
> >>>>> Don't just run the pipe. Inside it run some nylon string or something
> >>>>> strong, substantially longer than the pipe, so you can pull new wires
> >>>>> through easily. And leave it there even when you think you are done.
> >>>>> I would like to run one more wire to my attic, but it's too hard to
> >>>>> get it through hole in the plywood between floors one and two.
> >>>> Good fishing line would do the trick.
> >>>> Good tip.
> >>> Actually, get some of that nylon pull rope that they sell at Lowe's or
> >>> HD or at electrical places. And, when pulling a new wire into the
> >>> conduit, pull an extra piece of the nylon stuff for the next time.
> >> Good point.
> >> What is nylon pull rope? I guess I wil visit the local(1/2 mile away) HD
>
>
> > they probably won't have it at HD, you will likely have to go to a
> > real electrical supply house
>
> > nate
>
> There are small rolls at the big box stores in the electrical wiring
> section.
Not in my neck o' the woods. Of course, the help in the big boxen
wouldn't know a pull string if it fell on their heads. I really do
get sick of knowing more about what they sell than the "associates"
do.
Of course, the pricing is better at the supply house, so I just wait
until Saturday AM and go there. Only downside is when, as happened
recently, I got snowed in for two Saturdays in a row and thus my home
projects ground to a halt...
nate
Vinny From NYC
wrote Re Re: Running electrical wire through PVC pipe:
>Not in my neck o' the woods. Of course, the help in the big boxen
"boxen"? Wow, that's soooo cool.
Oren
>> >> What is nylon pull rope? �I guess I wil visit the local(1/2 mile away) HD
>>
>> >http://www.lanshack.com/Powr-Fish-Pull-Line-6500-feet-bucket-P2072C20...
>>
>> > they probably won't have it at HD, you will likely have to go to a
>> > real electrical supply house
>>
>> > nate
>>
>> There are small rolls at the big box stores in the electrical wiring
>> section.
>
>Not in my neck o' the woods. Of course, the help in the big boxen
>wouldn't know a pull string if it fell on their heads. I really do
>get sick of knowing more about what they sell than the "associates"
>do.
>
>Of course, the pricing is better at the supply house, so I just wait
>until Saturday AM and go there. Only downside is when, as happened
>recently, I got snowed in for two Saturdays in a row and thus my home
>projects ground to a halt...
>
>nate
The local HD store here keeps a box of nylon twine at the overhead
door exit. Used to bundle several pieces of trim or base molding
together.
I've cut 30 - 50 feet before - free. It is there for the customer
use.
Oren
wrote:
I know enough that fishing line is not used for pulling wire :-/
A local Casino paid (7.5M?) to have overhead lines and poles removed,
so they could expand building. That underground cable was 5 inches
wide (130,000 Volts?), along the Vegas Strip. What a pull that was,
eh?
Steve Barker
Andrew
> I was going to install 1 1/2 inch PVC pipe in the wall from the
> basement up to the second floor to make it easier to run more cable
> future. I thought about just running the electric wire in the pipe too
> but I though I read where someone on this group mentioned to not run
> electric wire through PVC.
>
> Did I misread something or is that true? It if is true, what is the
> problem with it.
>
> then if I do the job right, the won't be much reason to run more wire
> for a long, long time anyway.
>
> Thanks, David
PVC is commonly used for electric wire. Not a problem there. But you
should run two separate conduits: one for data signals and one for
120/240V signals. The 120/240V lines are likely to cause interference
in the data signals.
tra...@optonline.net
Now here's a question. When they build houses why don't they put in
a couple empty PVC conduits that run from basement to attic? It sure
would make it a hell of a lot easier to run any cables later on.
Especially in an age where people are adding all kinds of things,
data, voice, AC, etc. Yet, I've never seen this done. I guess
there could be some claim that it might let a fire spread easier, but
I tend to doubt that's really much of an issue. Even if it were,
there would be ways to still do it and seal it off.
mm
>
>The local HD store here keeps a box of nylon twine at the overhead
>door exit. Used to bundle several pieces of trim or base molding
>together.
Isn't that polypropylene, the cheap stuff, often hard to knot? Nylon
twine is much nicer and much more expensive.
krw
>On Feb 26, 7:35�am, Andrew <andrewkgent...@gmail.com> wrote:
>> On Feb 24, 11:34�am, hibb <ShyPic...@aol.com> wrote:
>>
>> > I was going to install 1 1/2 inch PVC pipe in the wall from the
>> > basement up to the second floor to make it easier to run more cable
>> > (data cable, TV Coax and such) �up there should I need to in the
>> > future. I thought about just running the electric wire in the pipe too
>> > but I though I read where someone on this group mentioned to not run
>> > electric wire through PVC.
>>
>> > Did I misread something or is that true? It if is true, what is the
>> > problem with it.
>>
>> > Sure seems like it would be easier to run wire in future projects. But
>> > then if I do the job right, the won't be much reason to run more wire
>> > for a long, long time anyway.
>>
>> > Thanks, David
>>
>> PVC is commonly used for electric wire. �Not a problem there. �But you
>> should run two separate conduits: one for data signals and one for
>> 120/240V signals. �The 120/240V lines are likely to cause interference
>> in the data signals.
>
>
>
>Now here's a question. When they build houses why don't they put in
>a couple empty PVC conduits that run from basement to attic?
Because it costs money. However, I did this in a few places in my
mother's house as they were building it, forty years ago.
>It sure
>would make it a hell of a lot easier to run any cables later on.
>Especially in an age where people are adding all kinds of things,
>data, voice, AC, etc. Yet, I've never seen this done. I guess
>there could be some claim that it might let a fire spread easier, but
>I tend to doubt that's really much of an issue. Even if it were,
>there would be ways to still do it and seal it off.
It's just a cost that few would every use. A builder isn't going to
throw a couple of hundred dollars down the rat hole if he doesn't
think people will pay even more. I'm quite sure that you could put it
in the contract, though. About now, I'm sure you could get them to
agree to let you do it at night. ;-)
DerbyDad03
> On Thu, 25 Feb 2010 14:00:16 -0800 (PST), N8N <njna...@hotmail.com>
>
> - Show quoted text -
re: "I've cut 30 - 50 feet before - free. It is there for the
customer use."
Yes, it's there for customer use, but it's not "free".
It's cost is included in the store's overall operating costs and
figured into the prices of the items on the shelf.
The string's not free, the coffee's not free, the non-help you get
from many of the associates is not free. You're just not paying for it
directly.
OK...I'll grant you the exception where you use the string and drink
the coffee without *ever* buying anything from the store. In that
case, it would be free.
Bob F
> On Wed, 24 Feb 2010 10:45:08 -0800 (PST), hibb <ShyP...@aol.com>
> wrote:
>
>> On Feb 24, 1:38 pm, mike <yellowbird...@hotmail.com> wrote:
>>> On Feb 24, 10:34 am, hibb <ShyPic...@aol.com> wrote:
>>>
>>>> I was going to install 1 1/2 inch PVC pipe in the wall from the
>>>> basement up to the second floor to make it easier to run more cable
>>>> (data cable, TV Coax and such) up there should I need to in the
>>>> future. I thought about just running the electric wire in the pipe
>>>> too but I though I read where someone on this group mentioned to
>>>> not run electric wire through PVC.
>>>
>>>> Did I misread something or is that true? It if is true, what is the
>>>> problem with it.
>>>
>>>> Sure seems like it would be easier to run wire in future projects.
>>>> But then if I do the job right, the won't be much reason to run
>>>> more wire for a long, long time anyway.
>>>
>>>> Thanks, David
>>>
>>>
>>> A separate issue is whether AC current might pose interference
>>> issues for various other types of lines.
>>
>> Thanks, Mike.
>>
>> I just googled on the issue I posted here and it looks like there is
>> a heat issue if electric wires are enclosed in a conduit.
>>
>> I really can't see me ever having to run more electric wire up there
>> as long as I live here. But I will surely run a conduit for the other
>> types of wire.
>>
>> Thanks, David
>
> The problem is that the hot and ground wires will short together
> inside the pvc. You will need to install a separate pipe for each
> wire, unless you wrap each wire with electrical tape so they can not
> short together. If you use steel wire, be sure it's galvanized or it
> will rust, or get some stainless steel piano wire, which will last
> longer. One other thing. Do not run water thru the pipe, or not
> sewer water either. Even if you tape the wires well, the water or
> sewerage will cause wires to short out.
14 inches and a 14 IQ.
HerHusband
> I was going to install 1 1/2 inch PVC pipe in the wall from the
> basement up to the second floor to make it easier to run more cable
> (data cable, TV Coax and such) up there should I need to in the
> future. I thought about just running the electric wire in the pipe too
> but I though I read where someone on this group mentioned to not run
> electric wire through PVC.
> Did I misread something or is that true? It if is true, what is the
> problem with it.
I just saw this posting, so I apologize if this has already been
answered.
The general code restriction is not to run "romex" style cables in
conduit. As you discovered, it is related to heat build-up from the
cables in the confined space of the conduit.
I researched this myself a couple years ago, and code does allow
exceptions to this when "short" conduit runs are used for physical
protection only. For example, I ran romex in conduit at my in-laws house,
from surface mounted outlets in the basement, up the wall to the floor
structure. It's open at the top for heat to escape, has an anti-short
bushing to prevent the conduit edge from cutting into the cable, and is
strictly for physical protection. My inspector had no problems with it.
But a two story run inside walls would probably be well outside that
exception.
> Sure seems like it would be easier to run wire in future projects. But
> then if I do the job right, the won't be much reason to run more wire
> for a long, long time anyway.
Technology changes quickly and it's not economical to install everything
in hopes you might someday use it (or worse yet, guess wrong and spend a
lot of money on something that's outdated in a few years).
I installed numerous boxes throughout our house with short conduit runs
to the crawlspace (capping the ends to prevent drafts and keep out
insects). I've replaced and reorganized various cables over the last
five years and it's one of the best decisions I've ever made. My only
regret is not installing larger conduit, as my needs have far outpaced
what I ever thought I would need them for.
Heat concerns are not an issue for data cables (Cat5, Cat 6), Coax,
phone, etc., so running conduit now for those is a great idea. Minimal
cost and no harm done if you never use it. But you'll be very thankful if
you do need it.
I do recommend installing the largest conduit you can afford that will
fit in the wall (remember couplings are larger than the outside of the
pipe itself). It's unlikely you would ever wish the conduit was smaller,
but as you install more "stuff" in coming years, you'll appreciate the
extra capacity.
As for power lines, I would run another conduit line (again, as big as
will fit), with large junction boxes at each floor. You could run romex
cables through the walls/ceilings, then transition to individual THHN
wires in the conduit. Individual wires are made for running in conduit,
and you can fit more in the same space than romex cables anyway.
Anthony
bud--
> Hi David,
>
>> I was going to install 1 1/2 inch PVC pipe in the wall from the
>> basement up to the second floor to make it easier to run more cable
>> (data cable, TV Coax and such) up there should I need to in the
>> future. I thought about just running the electric wire in the pipe too
>> but I though I read where someone on this group mentioned to not run
>> electric wire through PVC.
>> Did I misread something or is that true? It if is true, what is the
>> problem with it.
>
> I just saw this posting, so I apologize if this has already been
> answered.
>
> The general code restriction is not to run "romex" style cables in
> conduit. As you discovered, it is related to heat build-up from the
> cables in the confined space of the conduit.
>
> I researched this myself a couple years ago, and code does allow
> exceptions to this when "short" conduit runs are used for physical
> protection only. For example, I ran romex in conduit at my in-laws house,
> from surface mounted outlets in the basement, up the wall to the floor
> structure. It's open at the top for heat to escape, has an anti-short
> bushing to prevent the conduit edge from cutting into the cable, and is
> strictly for physical protection. My inspector had no problems with it.
> But a two story run inside walls would probably be well outside that
> exception.
>
The NEC explicitly allows Romex to be installed in PVC conduit (352.22).
(There are similar permissions for other raceways.)
Heat is a potential problem for multiple cables. It is covered in
Wayne's post.
--
bud--
hibb
Hi Anthony,
Thanks for your response. I am not familiar with the term "Romex"
cables. The electric wire I run labeled as 12-2 NM-B With Ground. I do
not know if it is romex cable or not but it does not mention romex
anywhere on the packaging as far as I can see. But I will google romex
and see what I can find.
I have already purchased electrical conduit to run a 1 1/2 diameter
line from the basement for electrical and another 1 inch conduit for
data stuff.
I am going to have speakers at the other end of the room from the
computer and mixer so I think I will run conduit up the wall and over
the ceiling for those wires in case I want to change those someday.
And I will install two Cat5 data outlets. One on each end of the room.
I think I will run conduit for those lines too because data wire
requirements change so much.
Thanks, David
HerHusband
> The NEC explicitly allows Romex to be installed in PVC conduit
> (352.22). (There are similar permissions for other raceways.)
> Heat is a potential problem for multiple cables.
Good catch. I missed that in my research a couple of years ago.
Still, the idea of installing conduit now for future work later, would seem
to increase the chance that someone might try to fit more than one cable in
the conduit.
One option that might prevent that is to install several smaller conduits,
such that it would be difficult to fit more than one cable in each. If
there were other routes available, it would reduce the temptation to force
them in. Just a thought...
Anthony
HerHusband
> The electric wire I run labeled as 12-2 NM-B With Ground.
"Romex" is a brand name. The 12-2 NM-B specification is more important
than the brand name. (12-2 will support up to 20 amps for typical runs).
I used the term Romex as that's how most folks refer to it, even though
it may be made by other manufacturers. Just like tissues are often
called "Kleenex", even though many other companies make them.
> I have already purchased electrical conduit to run a 1 1/2 diameter
> line from the basement for electrical and another 1 inch conduit for
> data stuff.
That sounds OK to me. Based on the correction "Bud" supplied, you could
run a single NM-B cable in the large conduit now. If you ever need to
run additional lines, you could pull that cable, install junction boxes
top and bottom, and run individual wires in the conduit. Or, go ahead and
transition now to save future work.
Better yet, dedicate the 1-1/2 inch line to data needs, and install
additional 3/4" conduit runs for future power runs. I would cap any
unused lines to keep out insects and drafts.
Oh, and just for clarification, make sure you use grey colored PVC
"conduit" and not white PVC water pipe. You wouldn't want someone cutting
into what they think is a water line, only to cut into power or data
cables.
> I am going to have speakers at the other end of the room from the
> computer and mixer so I think I will run conduit up the wall and over
> the ceiling for those wires in case I want to change those someday.
I mounted in-wall speakers in our living room, but did not use conduit
for those lines. It's unlikely I would ever need to relocate the
speakers, and if I did it would involve drywall work anyway. But, if you
plan to move things around often, or future access would be difficult,
the conduit will really make things easier.
Note: If you run speaker cables in the wall, make sure you use speaker
cables listed for that purpose. I think it's "CL-2" cable with a fire
retardant outer jacket that also makes it easier to pull.
> And I will install two Cat5 data outlets. One on each end of the room.
> I think I will run conduit for those lines too because data wire
> requirements change so much.
I installed a double-gang sized box on each wall of our living room and
every bedroom, with two 3/4" conduits running to our crawlspace. These
are for data purposes only. It's not always easy to forsee how furniture
might be moved around, and it's not a big cost to add a few more boxes to
simplify changes later.
A few of the boxes have gone unused, but I've been surprised how much
I've needed most of them. I've run cat5 cables through most of them to
connect the computers in various rooms. Two other cat5 cables run to our
living room for my blu-ray player and a network media streamer (lets me
watch TV shows recorded on the PC in my office).
Install blank cover plates on the boxes you don't use. Special plates
with "keystone" jacks let you run all sorts of connections. For
instance, the box in my office has two cable lines (one from cable TV,
one from an outdoor antenna), two phone lines, and two cat5 ethernet
lines.
There isn't anyplace in the house I regret installing the boxes, but I do
wish I had installed additional boxes in the home-office, our bedroom,
and even the kitchen. I quickly ran out of ports for my home network, so
I worked around that by installing a network switch in the crawlspace (I
was fortunate to have a power outlet available there). I didn't forsee
the need to run much data to the bedroom, so I didn't plan ahead well
enough there. I've already had to fish a couple of extra cables in the
last five years. A box and conduit would have made things much easier.
Of course, about a month after I ran network cables to every room, I
bought a wireless router and don't need the wired connections for my
laptop now. :) But the wired connections are still used between desktop
PC's and the media devices in our living room. Nice thing about the
conduit, I can easily pull out the unused network cables and feed
something else in if my needs change later.
Anthony
Wayne Whitney
> Still, the idea of installing conduit now for future work later, would seem
> to increase the chance that someone might try to fit more than one cable in
> the conduit.
If the piece of conduit is just used as a sleeve, then you can put as
many electrical cables in it as will fit without damage, as long as
you pay attention to derating. You don't have to follow the conduit
fill percentages, they apply only to conduit systems. As mentioned
previously, for NM #14 and #12 cables, up to 9 current carrying
conductors are OK without reducing the ampacity below the usual 15 and
20 amps, respectively.
Cheers, Wayne
Wayne Whitney
> You still have a fill limit on these short sections of pipe (60%)
I don't believe the 60% fill limit applies to sleeves, only short
sections of a complete conduit system. The way I think of sleeves,
they are not part of the electrical system. If the installation is
NEC-compliant without the sleeve, then the presence of the sleeve
doesn't change anything, it was just an aid in installing the cables.
Cheers,
Wayne
HerHusband
> many electrical cables in it as will fit without damage, as long as
> you pay attention to derating. You don't have to follow the conduit
> fill percentages, they apply only to conduit systems. As mentioned
> previously, for NM #14 and #12 cables, up to 9 current carrying
> conductors are OK without reducing the ampacity below the usual 15 and
> 20 amps, respectively.
Well now I'm confused... :) At what point does does conduit become a full
"conduit system" that restricts NM cables in the conduit?
When I tried to decipher the code a couple years ago, I understood it to
mean "short" sections of conduit (i.e. 4 feet or less) where at least one
end was open for air flow was OK. Wouldn't a long "sleeve" of conduit (say
20 feet long from basement to attic) encounter the heat buildup the
restriction is trying to prevent?
I'm not trying to be sarcastic, I just don't understand what the deciding
factor is for NM cables in conduit. It would be good to know for future
work.
Thanks,
Anthony
hibb
Thanks for all that information.
Heck, I was going to run 4 of the 12-2 NB wires through that 1-1/2
inch by 10 ft long pipe. It is the gray pipe used for electrical runs,
btw. Looks like that could be a problem, eh?
Thanks, David
tra...@optonline.net
> > The electric wire I run labeled as 12-2 NM-B With Ground.
>
> "Romex" is a brand name. The 12-2 NM-B specification is more important
> than the brand name. (12-2 will support up to 20 amps for typical runs).
>
> I used the term Romex as that's how most folks refer to it, even though
> it may be made by other manufacturers. Just like tissues are often
> called "Kleenex", even though many other companies make them.
>
> > I have already purchased electrical conduit to run a 1 1/2 diameter
> > line from the basement for electrical and another 1 inch conduit for
> > data stuff.
>
> That sounds OK to me. Based on the correction "Bud" supplied, you could
> run a single NM-B cable in the large conduit now. If you ever need to
> run additional lines, you could pull that cable, install junction boxes
> top and bottom, and run individual wires in the conduit. Or, go ahead and
> transition now to save future work.
Maybe I missed something here, but based on what Wayne and Bud said,
it sounds to me like you could run four 14-2 Romex through a single
conduit.
Wayne:
"In terms of overheating, you need to watch how many current carrying
conductors (CCCs) you run together for a significant length. If you
have too many together you have to "derate" each conductor so that it
carries less current, or alternatively upsize the conductor for a
given current. The rules are complicated, and derating potentially
starts at 4 CCCs. However, for NM cable in #14 and #12 sizes, you can
run up to 9 CCCs and still maintain the usual 15A and 20A capacities,
respectively"
Steve B
by a licensed electrician. Are we talking about sprinkler PVC, or
electrical rated PVC?
Steve
Wayne Whitney
> Heck, I was going to run 4 of the 12-2 NB wires through that 1-1/2
> inch by 10 ft long pipe. It is the gray pipe used for electrical
> runs, btw. Looks like that could be a problem, eh?
(4) is the maximum number of 12-2 NM-B cables you can bundle together
(e.g. run through a sleeve like you are doing) and still maintain the
20 amp capacity (assuming no other correction factors, like elevated
ambient temperature). So you are fine, just don't put a 5th one in
there. As for the sleeve, you can use whatever material is
convenient.
Cheers, Wayne
Wayne Whitney
> As for the sleeve, you can use whatever material is convenient.
Oops, I need to amend that. The one wrinkle is that you normally have
to support your NM cable every 4.5 feet (NEC 334.30). The allowable
exceptions are (1) you are doing remodel work and fishing the cable
(NEC 334.30(B)(1)) or (2) you are running the cable inside a raceway
(the NEC term for conduit) that provides protection from physical
damage.
So, if your wall is open, and you are installing a sleeve and running
NM cable in the sleeve, then you have to use a raceway, like PVC
electrical conduit. But if you are doing remodel work, and come
across an existing unused pipe in a finished wall, you can fish your
wire down it without regard to what the sleeve is made of.
Cheers,
Wayne
Wayne Whitney
> Well now I'm confused... :) At what point does does conduit become a
> full "conduit system" that restricts NM cables in the conduit?
When you want to use that conduit system for its normal purpose, to be
able to run individual electrical conductors like THHN, XHW, etc. In
that case, you have to count any NM cables also in the conduit towards
the conduit fill.
If you just have a sleeve or guideway for cables, like a piece of pipe
with open ends, then conduit fill does not apply, in my opinion. But
see my other post for the restrictions about supporting the NM cable.
BTW, there is obviously some variation in understanding about this
issue. So if you are planning to do this, you might want to check
with your inspector first. [If they say it is not allowed, you could
ask them what NEC article it violates.] You might find yourself in a
situation where your inspector disagrees and you decide it isn't worth
challenging.
> Wouldn't a long "sleeve" of conduit (say 20 feet long from basement
> to attic) encounter the heat buildup the restriction is trying to
> prevent?
Conduit fill and derating are two different things. Conduit fill is
about avoiding damage to the conductors while installing them (cables
already have an outer sheath to help with that), while derating is
about keep the conductors from overheating when multiple conductors
are in close proximity.
BTW, you could have a derating issue due to bundling of cables without
any sleeve. E.g. if you drill a series of holes in a stud wall and
pack a bunch of cables tightly together through the holes (such as
more than 4 12/2 or 14/2 NM cables), that could be derating problem.
Certainly it would be if you also cable tied the cables together
in between the studs.
Cheers,
Wayne
Wayne Whitney
> BTW, you could have a derating issue due to bundling of cables without
> any sleeve. E.g. if you drill a series of holes in a stud wall and
> pack a bunch of cables tightly together through the holes (such as
> more than 4 12/2 or 14/2 NM cables), that could be derating problem.
> Certainly it would be if you also cable tied the cables together
> in between the studs.
In fact, in the 2008 NEC, you have to derate any time you have more
than one cable going through a hole in framing that will be sealed
with thermal insulation, foam, or caulk. NEC 334.80 says, in part:
Where more than two NM cables containing two or more
current-carrying conductors are installed, without maintaining
spacing between the cables, through the same opening in wood framing
that is to be fire- or draft-stopped using thermal insulation,
caulk, or sealing foam, the allowable ampacity of each conductor
shall be adjusted in accordance with Table 310.15(B)(2)(a) and the
provisions of 310.15(A)(2), Exception, shall not apply.
Cheers,
Wayne
HerHusband
> Conduit fill and derating are two different things. Conduit fill is
> about avoiding damage to the conductors while installing them (cables
> already have an outer sheath to help with that), while derating is
> about keep the conductors from overheating when multiple conductors
> are in close proximity.
Thanks for the clarification. I appreciate it!
> there is obviously some variation in understanding about this
> issue. So if you are planning to do this, you might want to check
> with your inspector first.
So far, the only conduit related issue my inspectors have been concerned
with is bushings on the open ends of the conduit to prevent the conduit
from chafing the cables.
On a related note, I wonder how an open two story vertical run of conduit
would be viewed from a fire spread point of view? Our building inspectors
were strict about sealing all openings at floors and ceilings to prevent
fire spread. It seems like an uninterupted vertical run of conduit would
act a lot like a chimney, allowing a fire on the lower level a straight
path to the top floor (or attic).
> BTW, you could have a derating issue due to bundling of cables without
> any sleeve. E.g. if you drill a series of holes in a stud wall and
> pack a bunch of cables tightly together through the holes
I was surprised to learn on my last inspection that it was actually OK to
run two cables through the same clamp on the breaker panel. It may pass
inspection, but it didn't seem right to me. I prefer one cable per clamp.
Anthony
Wayne Whitney
> So far, the only conduit related issue my inspectors have been
> concerned with is bushings on the open ends of the conduit to
> prevent the conduit from chafing the cables.
Yes, that is a good idea, and in certain code sections is called out
explicitly.
> On a related note, I wonder how an open two story vertical run of
> conduit would be viewed from a fire spread point of view?
I would expect it would be required to be fire caulked. My building
inspector required every penetration of top and bottom plates to be
fire caulked. Where I used EMT to sleeve NM cable for protection from
physical damage in a thin (2" framing) wall, I used bushings and
caulked the openings.
> I was surprised to learn on my last inspection that it was actually
> OK to run two cables through the same clamp on the breaker panel. It
> may pass inspection, but it didn't seem right to me. I prefer one
> cable per clamp.
Are you talking about clamps that you installed in a KO on the panel?
The manufacturer's packaging or instructions should specify what
combinations of cables it is to be used with.
Cheers, Wayne
hibb
OK, so running four 12-2 NM B cables in the 1-1/2 inch conduit. Again,
I already have the gray conduit specifically meant for electrical.
I am not sure how I can support the wire every 4 1/2 feet inside the
conduit. How is that done? The whole of the 10 feet of conduit will be
vertical, btw.
Also, what is a good way to tag the wires so I would know what each
wire goes to as they exit the conduit?
Thanks, David
JIMMIE
> On Thu, 25 Feb 2010 14:40:00 -0800, Oren <O...@127.0.0.1> wrote:
>
> >The local HD store here keeps a box of nylon twine at the overhead
> >door exit. Used to bundle several pieces of trim or base molding
> >together.
>
> Isn't that polypropylene, the cheap stuff, often hard to knot? Nylon
> twine is much nicer and much more expensive.
Polypropylene is Dupont Dacron, used for ropes on sailboats.
Jimmie
HerHusband
>> conduit would be viewed from a fire spread point of view?
> I would expect it would be required to be fire caulked. My building
> inspector required every penetration of top and bottom plates to be
> fire caulked. Where I used EMT to sleeve NM cable for protection from
> physical damage in a thin (2" framing) wall, I used bushings and
> caulked the openings.
That seems like it would make future additions more difficult, having to
dig out the caulk before a new cable could be run. I wonder if a junction
box at the top and bottom would serve a similar function, but still allow
easy access in the future. Just thinking out loud...
> Are you talking about clamps that you installed in a KO on the panel?
Yeah, sorry for the vague description. I always use one clamp per cable in
the knock-outs, so it didn't even occur to me you could run more than one.
I was really surprised when the inspector said I could if I needed to.
Anthony
HerHusband
> know what each wire goes to as they exit the conduit?
A sharpie pen works great for writing identifications on the outer covering
of NM-B cables. If you're feeding multiple cables at once, you can write
the ID on the cables first, then feed them through the conduit, something
that wouldn't work well with adhered tags or labels.
Anthony
bud--
352 Rigid PVC conduit
"352.22 Number of conductors
....
Cables shall be permitted to be installed where such use is not
prohibited by the respective cable articles. The number of cables shall
not exceed the allowable percentage fill specified in Table 1, Chapter 9."
Identical language was added to most raceway articles (xxx.22) in the
2002NEC, probably to make existing practice clear. I would expect
inspectors would apply the same fill restrictions to PVC water pipe (if
they allowed water pipe). I haven't tried, but it would probably be
difficult to pull in Romex that did not comply with the fill restrictions.
The NEC doesn't specify a length or reason for using PVC conduit.
Fire stopping might actually be enforced by the building inspector (not
electrical inspector).
--
bud--
Wayne Whitney
> OK, so running four 12-2 NM B cables in the 1-1/2 inch conduit. Again,
> I already have the gray conduit specifically meant for electrical.
>
> I am not sure how I can support the wire every 4 1/2 feet inside the
> conduit. How is that done? The whole of the 10 feet of conduit will be
> vertical, btw.
No, that is the point, if you use the gray electrical conduit, you
don't have to support the NM cable every 4 1/2 feet inside the
conduit.
Cheers, Wayne
bud--
"344 Non-metallic sheathed cable: Types NM, .... [commonly called Romex]
344.30 Securing and Supporting.
...4 1/2 ft...12 inches....
Sections of cable protected from physical damage by raceway shall not be
required to be secured withing the raceway."
I would think an inspector would view a raceway used to fish cables the
same as one used for physical protection.
Can't remember if "raceway" has been defined in this thread, but it is a
hollow wiring method installed without wires that wires are added to -
like PVC conduit.
--
bud--
Wayne Whitney
> The real question is what your AHJ thinks. It says "nipples less
> than 24 inches", not conduit systems. In this jurisdiction that is
> what you call a sleeve. If this is a conduit system you can't
> exceed the fill in any of it.
In the NEC 2008, Chapter 9 Table 1 gives the conduit fill allowances.
Note 2 says "Table 1 applies only to complete conduit or tubing
systems and is not intended to apply to sections of conduit or tubing
used to protect exposed wiring from physical damage." So it doesn't
apply to sleeves.
Note 4 says "(4) Where conduit or tubing nipples having a maximum
length not to exceed 600 mm (24 in.) are installed between boxes,
cabinets, and similar enclosures, the nipples shall be permitted to be
filled to 60 percent of their total cross-sectional area, . . ." So
this is relaxing the Table 1 requirements for certain parts of a
conduit system, it does not apply to sleeves.
> Also there are plenty of AHJs who say if you pull wire in it, you need
> to use a listed raceway. I have seen 4" white PVC pipes under
> driveways failed because they pulled a 14/2 UF in it. Personally I
> don't agree with that one.
Yes, it is completely illogical to say "this installation would be
compliant if that piece of PVC pipe weren't there, but now that it is,
it is in violation".
> Be careful to call these things ducts when you are talking to an
> inspector since that is acknowledged in the code but not defined or
> regulated. It might give you a better case.
Good idea.
Cheers,
Wayne
hibb
Great. I think I am good to go now.
Thanks, David
hibb
David
bud--
> On 2010-03-02, gfre...@aol.com <gfre...@aol.com> wrote:
>
>> The real question is what your AHJ thinks. It says "nipples less
>> than 24 inches", not conduit systems. In this jurisdiction that is
>> what you call a sleeve. If this is a conduit system you can't
>> exceed the fill in any of it.
>
> In the NEC 2008, Chapter 9 Table 1 gives the conduit fill allowances.
> Note 2 says "Table 1 applies only to complete conduit or tubing
> systems and is not intended to apply to sections of conduit or tubing
> used to protect exposed wiring from physical damage." So it doesn't
> apply to sleeves.
>
Well ain't that interesting.
IMHO it conflicts with 322.22 for PVC conduit (and xxx.22 for most other
raceways):
"Cables shall be permitted to be installed where such use is not
prohibited by the respective cable articles. The number of cables shall
not exceed the allowable percentage fill specified in Table 1, Chapter 9"
=============
The 2002 NEC change proposal (for xxx.22) came from the code writing
panel and says very little about why the change was made. The
explanation is the change "clarifies that cables, where permitted
elsewhere in the code, are allowed to be used in a raceway." The
language was later changed to "where such use is not prohibited".
=============
From the NFPA/IAEI code changes book:
Using raceways as isolated protective sleeves for cables was accepted in
the past.
It appears that the proposal may be for raceways that are connected to
the electrical system on one end. There are 2 examples shown.
One example is a box with a receptacle that has a conduit out the top
and has a Romex run through the conduit into the box. The top of the
conduit has a conversion fitting with a Romex connector.
[It is common practice to use essentially the same arrangement, without
the Romex connector, to protect exposed Romex.]
The other example is for one or more Romex runs into a panel through a
conduit as allowed in 312.5-C.
===============
Seems like the application, as written, would be Table 1, Note 2 applies
in general but 322.22 applies specifically to all uses of PVC conduit.
But most raceways have an xxx.22 section, so I don't know what Note 2
applies to. Not likely that is what was intended.
If Table 1, Note 2 applies to all raceways that protect from physical
damage that leaves isolated raceways, as used in this thread, covered by
xxx.22 (which may or may not have been the intent).
This is unreasonable ambiguity. I guess the answer is ask the inspector.
--
bud--
Wayne Whitney
> Wayne Whitney wrote:
>
>> In the NEC 2008, Chapter 9 Table 1 gives the conduit fill allowances.
>> Note 2 says "Table 1 applies only to complete conduit or tubing
>> systems and is not intended to apply to sections of conduit or tubing
>> used to protect exposed wiring from physical damage." So it doesn't
>> apply to sleeves.
>
> Well ain't that interesting. IMHO it conflicts with 322.22 for PVC
> conduit (and xxx.22 for most other raceways):
> "Cables shall be permitted to be installed where such use is not
> prohibited by the respective cable articles. The number of cables shall
> not exceed the allowable percentage fill specified in Table 1, Chapter 9"
I would say that Note 2 is part of Table 1, Chapter 9, so that the
322.22 reference includes Note 2. I don't see the ambiguity.
Cheers,
Wayne
Wayne Whitney
>> Well ain't that interesting. IMHO it conflicts with 322.22 for PVC
>> conduit (and xxx.22 for most other raceways):
>> "Cables shall be permitted to be installed where such use is not
>> prohibited by the respective cable articles. The number of cables shall
>> not exceed the allowable percentage fill specified in Table 1, Chapter 9"
>
> I would say that Note 2 is part of Table 1, Chapter 9, so that the
> 322.22 reference includes Note 2. I don't see the ambiguity.
Oops, that should be 352.22 for PVC conduit.
Wayne
bud--
That works.
For the "sleeve", it is not intended to protect from physical damage, so
fill restrictions apply via 322.22 to Chapter 9, Table 1. Heat is as
much a problem as full wiring systems.
Also wire ampacity derating applies, as you wrote long ago.
--
bud--
Wayne Whitney
> Wayne Whitney wrote:
>
>> In the NEC 2008, Chapter 9 Table 1 gives the conduit fill
>> allowances. Note 2 says "Table 1 applies only to complete conduit
>> or tubing systems and is not intended to apply to sections of
>> conduit or tubing used to protect exposed wiring from physical
>> damage." So it doesn't apply to sleeves.
>
> For the "sleeve", it is not intended to protect from physical
> damage, so fill restrictions apply via 322.22 to Chapter 9, Table 1.
Well we are still reading "Note 2" differently. The first half of the
sentence already exempts all sleeves. The second half of the sentence
elaborates and gives a specific example but doesn't in any way limit
the first half. The upshot is that all sleeves are exempt.
> Heat is as much a problem as full wiring systems.
Right, and that is handled by the derating requirements when bundling,
not by conduit fill. Conduit fill is for protection of conductors
from damage during installation.
Cheers,
Wayne
bud--
> On 2010-03-03, bud-- <remove....@isp.com> wrote:
>
>> Wayne Whitney wrote:
>>
>>> In the NEC 2008, Chapter 9 Table 1 gives the conduit fill
>>> allowances. Note 2 says "Table 1 applies only to complete conduit
>>> or tubing systems and is not intended to apply to sections of
>>> conduit or tubing used to protect exposed wiring from physical
>>> damage." So it doesn't apply to sleeves.
>> For the "sleeve", it is not intended to protect from physical
>> damage, so fill restrictions apply via 322.22 to Chapter 9, Table 1.
>
> Well we are still reading "Note 2" differently. The first half of the
> sentence already exempts all sleeves. The second half of the sentence
> elaborates and gives a specific example but doesn't in any way limit
> the first half. The upshot is that all sleeves are exempt.
I do read it different. IMHO Note 2 is taken as a whole and not split
into 2 sections. If the first half is independently applied, the second
half is not necessary.
Some of the other notes (5 and 9) are specifically for cable, which
would not likely be used in "complete conduit ... systems".
>
>> Heat is as much a problem as full wiring systems.
>
> Right, and that is handled by the derating requirements when bundling,
> not by conduit fill. Conduit fill is for protection of conductors
> from damage during installation.
I figured out temperature was the wrong limitation right after I hit Send.
As you said, the point of Table 1 is to prevent damage to wiring at
installation. By your reading of Note 2, there is no limitation on the
number of cables that can be fished into a sleeve, and no protection
from installing too many cables. The limit that would protect a
"complete system" would not apply to a sleeve.
--
bud--
Wayne Whitney
> Wayne Whitney wrote:
>
>> In the NEC 2008, Chapter 9 Table 1 gives the conduit fill
>> allowances. Note 2 says "Table 1 applies only to complete conduit
>> or tubing systems and is not intended to apply to sections of
>> conduit or tubing used to protect exposed wiring from physical
>> damage."
>
> I do read it different. IMHO Note 2 is taken as a whole and not
> split into 2 sections. If the first half is independently applied,
> the second half is not necessary.
I see the second half of the sentence as only an elaboration and
explicit identification of the most common case of the first half. It
is like saying "Crash test regulations apply only to vehicles with 4
or more wheels and are not intended to apply to motorcycles." That
sentence means to me that crash test regulations do not apply to
vehicles with 3 wheels.
> As you said, the point of Table 1 is to prevent damage to wiring at
> installation. By your reading of Note 2, there is no limitation on
> the number of cables that can be fished into a sleeve, and no
> protection from installing too many cables. The limit that would
> protect a "complete system" would not apply to a sleeve.
That's correct, but I don't see any problem with that. Cables have an
overall jacket that will help protect the conductor insulation from
damage. And a sleeve is likely to be a shorter run which would
require less pulling force than many "complete system" installations.
Cheers, Wayne
dpb
...
> As you said, the point of Table 1 is to prevent damage to wiring at
> installation. By your reading of Note 2, there is no limitation on the
> number of cables that can be fished into a sleeve, and no protection
> from installing too many cables. The limit that would protect a
> "complete system" would not apply to a sleeve.
The Note does not supersede nor provide relief from the general
workmanship clause to cover flagrant abuse of the privileges granted
therein.
--