Opinions on running wire in cold-air return
Chris
and would only let me "unofficially" run two 2" conduits from attic to
basement. Needless to say I belive that won't be near enough. The way
the house is built there is no real way to get to attic to basement
unless its an outside wall. I was looking for alternatives and realized
I could probably run all my needed wire in the cold-air return.
I realize this could quickly turn into a religous war but I'm after
opinions and facts. Any websites you could point me to would be an
additional plus. I'm looking to run cat-5 for phone, data and IR, plus
coax and probably speaker wire. What would be the best way of doing this?
Thanks for the input!
Chris
Robert L Bass
Please *under no circumstances* do that. It's a major electrical code (NEC)
violation and a potential hazard. There are numerous ways to go from attic
to basement in a finished house. If you like, take some time browsing my
FAQ pages. I've written instructions on several of my favorite techniques.
There's no rocket science nor specialty tools involved -- just a bit of
patience and a few round-about methods I've conjured up over the years.
Regards,
Robert L Bass
=============================>
Bass Home Electronics
The Online DIY Alarm Store
http://www.Bass-Home.com
2291 Pine View Circle
Sarasota, FL 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
rober...@comcast.net
=============================>
"Chris" <""news\"@base 2 technology.com> wrote in message
news:uah5p9c...@corp.supernews.com...
Chris
I understand that its a bad idea but I thought thats what plenum rated
cat-5 and other wiring was for...cold-air returns....if not..then what
is plenum for? I thought the point was that it wasn't as combustable.
I guess thats why I'm posting to this group....thoughtful well informed
answers...
Karl Denninger wrote:
> DO NOT do this.
>
> There are always other ways. You may have to work to find them, but they
> always exist. I had to pull wire to the garage attic in my old house, then
> down through a conduit (in the garage) to the bottom of the wall, and into
> the basement.
>
> Doing what you're talking about is a major NEC violation and if you go to
> sell the house and the buyer has it inspected I can guarantee it will be
> flagged. The buyer will likely force you to rip it all out. Its also quite
> hazardous in its own right.
>
> The only wire allowed in a cold air return duct is wire NECESSARY to control
> items IN the duct (like a damper)
>
> There is "plenum rated wire", but a plenum is NOT a cold-air return DUCT.
>
> My advice - don't do it.
>
> --
--
"In Italy for thirty years under the Borgias they had warfare, terror,
murder, bloodshed -- they produced Michelangelo, Leonardo da Vinci and the
Renaissance. In Switzerland they had brotherly love, five hundred years of
democracy and peace and what did that produce? The cuckoo clock." -Orson
Welles, script of _The Third Man_ (1949).
Chris
Shelley Cheslow
"Infrastructure Wiring for Existing Homes" at
http://www.copper.org/pub_list/telecommunications.html. I just received this
video this weekend and it is very worth the $30 in my opinion. It does a
very good job at explaining the *right* way of running cable through your
house. You'll also want to look at the specialty tools available at
http://www.lsdinc.com/, but when you're ready to order you can get better
prices from http://www.worthdist.com/.
Hope this helps,
Alan
Robert L Bass
off. The pages you want are under "FAQ | Alarm Systems | ..."
--
Regards,
Robert L Bass
=============================>
Bass Home Electronics
The Online DIY Alarm Store
http://www.Bass-Home.com
2291 Pine View Circle
Sarasota, FL 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
rober...@comcast.net
=============================>
"Chris" <""news\"@base 2 technology.com> wrote in message
news:uahakil...@corp.supernews.com...
Skip
> Ok then maybe I'm really confused..I've read this group long enough that
> I understand that its a bad idea but I thought thats what plenum rated
> cat-5 and other wiring was for...cold-air returns....if not..then what
> is plenum for? I thought the point was that it wasn't as combustable.
>
> I guess thats why I'm posting to this group....thoughtful well informed
> answers...
use in commercial buildings where the space above the suspended
ceiling acts as the air return with no ducted returns. The rating is
simply fire resistant and less toxic emissions when smoldering or
burning. It is not for running in ducting.
Many here may be better informed....
Steve
In commercial buildings, the space above a ceiling is often
used for return air, necessitating special ratings on cable
that is to be placed there.
If a building actually has ductwork installed for return
air, then you do not need plenum-rated cable (in most
cases). Note, however, that you still can not install wire
inside the ducts themselves, regardless of the type used.
I'd say you ought to fill the conduit up first and then
worry about it... you can do a lot with 2 - 2" pipes!
Regards,
Steve
"Chris" <""news\"@base 2 technology.com> wrote in message
news:uahai6r...@corp.supernews.com...
Don
Is he going to live there and pay the taxes?
If YES, then he should be able to tell you how you want it built but if the
answer is NO, then it is your decision.
If you let him decide, then you have to accept the results and additional
problems and costs involved in having the home finished the way you want it.
--
Don
Home of JEANNIE
The House That Listens
As seen on HGTV's Dream Builder Show
and the Featured Home of the Month
Home Automation magazine
March 2002 issue
Cheap
Is that allowed?
"Karl Denninger" <ka...@FS.Denninger.Net> wrote in message
news:a8aveg$62l$0...@pita.alt.net...
> A "plenum" is an enclosed space but NOT a duct.
>
> Sometimes in commercial buildings you see ceiling spaces (between the
> ceiling tile and the actual floor of the next level up) used as a cold air
> return, and of course in some places (computer rooms primarily) you have
> raised floors and air handling going on (usually AC supply) under there.
>
> It is specifically prohibited to run cable in ductwork (as opposed to a
> plenum) UNLESS it is necessary to control something INSIDE the ductwork,
and
> then it is ok by code only to the MINIMAL extent NECESSARY to do so.
>
> This is one of the things that inspectors will go batshit over.
>
> BTW, Plenum-rated cable typically has a teflon jacket. It won't burn, but
> it WILL decompose at high enough temperatures - and when it does what is
> released is PHOSGENE GAS. Not exactly what you want to be inhaling!
>
> (I used to do this stuff - data wiring - for a living in commercial
> buildings....)
>
> --
> --
> Karl Denninger (ka...@denninger.net) Internet Consultant & Kids Rights
Activist
> http://www.denninger.net Cost-effective Consulting
> http://childrens-justice.org SIGN THE UPREPA PETITION TODAY
>
> In article <uahai6r...@corp.supernews.com>,
wert
problems.
i woudnt do 110v though.
Chris
a thermostat or to close a duct. Damn....And here I wanted to hardware a
lot of my stuff..I'm just not sure how I'm going to run lots of wire
from top top bottom in a retrofit....even if I cut out squares of
drywall and try and drill though the joists its gonna be a pain...if
anybody has any pointers on how to run a bunch of wire (cat-5, coax,
speaker, IR, etc) from attic to basement I'm all ears.
Brian wrote:
> Sure, if it's necessary for the duct to watch TV. If not, then it's
> not allowed.
>
> [] [] "Cheap" <cheap.spam...@excite.spam> arranged some electrons to say:
--
HAM AND EGGS A day's work for a chicken; A lifetime commitment for a pig.
Lewis Gardner
>If anybody has any pointers on how to run a bunch of wire
> ... from attic to basement I'm all ears.
Look for some closets that line up and put a small chase in there. Look at
the walls that contain the DWV (drain, waste, vent - big pipe) plumbing,
there is usually some space there. It can be done. Don't use the inside of
ductwork but you might look at where the ducts are located and there may be
some space next to the duct.
Check out http://www.fluidmaster.com/pdf/access_panel_instructions.pdf for
some nice access panels. They don't look too bad once painted to match the
wall.
Joe Greco
:So bottom line is nothing gets run in a duct unless its wire needed for
:lot of my stuff..I'm just not sure how I'm going to run lots of wire
:from top top bottom in a retrofit....even if I cut out squares of
:drywall and try and drill though the joists its gonna be a pain...if
:anybody has any pointers on how to run a bunch of wire (cat-5, coax,
:speaker, IR, etc) from attic to basement I'm all ears.
Yeah, they're even cranky about running things like unbroken(!) NMT in
ducts. Like there aren't bigger problems to worry about by the time
something in a duct is causing NMT-enclosed wire to burn. Heh.
I'm not clear on whether you said you actually _got_ to install two 2"
conduits or if the builder offered you the chance and you refused. If
the latter, /big/ mistake. A 2" conduit may not sound like much, but
you can run 48 runs of Cat5 through it without trouble. (It violates
the capacity limit for 2" conduit, but most electrical inspectors do not
care what you do with low voltage wiring in conduit.) If I were you, I
would carefully reconsider the path the builder had intended to let you
run those conduits, and GO DO IT.
Otherwise...
Look for alternative methods of penetration. Plumbing is occasionally a
way to go: builders like straight drops for toilets and the like. You
/might/ find that you have a free space from the basement to the attic
(remember, there are vent pipes) and you might be able to use that space.
More likely, there will simply be a common wall at that point that you may
leverage to your advantage. There are a lot of iff's though. :-)
Have you looked for a clothes chute? If there's a CC that goes from the
second floor to the basement, it's almost certain that you can use part
of the adjoining wall.
If that fails, invest some time...
I *highly* recommend installing conduit of some sort. Whatever they call
the PVC stuff is probably sufficient. We're unlucky and live less than a
mile from a radio station with multiple antennas, so I've ended up running
3/4" NMT to all our wall boxes, and aggregate into 2" at a few spots
throughout the house before coming back to the demarc. But radio
interference on the phones is no longer a consideration. :-)
Patching drywall isn't terribly difficult if you take the time, effort, and
spend a little money to do it right. I'm just about to the point where I
want to get that hopper gadget that professionals use to blow texture, since
our house has some untextured (previously wallpaper) walls anyways.
So basically find the best place to go vertical, break open the wall, and
go nuts. Put in vastly more capacity than you think you'll need. Be sure
not to weaken structural supports though; check with your builder if you
need more info.
And mildly off-topic: I'd always been an advocate of the wall-ring
approach, using the little plastic or metal "data" rings, and that is a
nice way to go. But fishing for wires can be a nuisance at times,
especially if you have a box in a weird location.
I highly recommend the extra effort involved in putting conduit in anywhere
you might want a jack. It's a large up-front investment of time, but if
done right, it's something you'll never need to revisit. I've been putting
in 4" square electrical boxes, wide enough for a double plate even though
I've only been doing single in most places. The boxes are 2" deep and I
mount them a bit further back than usual and get a really deep mud ring, so
I end up with over 3" depth in the box. I can coil up some coax and
terminate it and still have lots of room for Cat3/5.
... JG
previous^@hotmail.com seismo
low voltage wiring and the NEC.
"Chris" <""news\"@base 2 technology.com> wrote in message
news:uah5p9c...@corp.supernews.com...
Robert L Bass
operation of the duct itself.
Regards,
Robert L Bass
=============================>
Bass Home Electronics
The Online DIY Alarm Store
http://www.Bass-Home.com
2291 Pine View Circle
Sarasota, FL 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
rober...@comcast.net
=============================>
"Cheap" <cheap.spam...@excite.spam> wrote in message
news:JN9q8.1418$8i2....@news2.mts.net...
Robert L Bass
Only wire needed to operate equipment in the duct that is part of the duct
system is allowed. Even thermostat runs back to the furnace don't belong in
the duct.
Do not despair, though. There are many ways to get a wire to the attic in a
finished home. If you need some help, give me a call. I can explain some
different things you can do.
Regards,
Robert L Bass
=============================>
Bass Home Electronics
The Online DIY Alarm Store
http://www.Bass-Home.com
2291 Pine View Circle
Sarasota, FL 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
rober...@comcast.net
=============================>
"Chris" <""news\"@base 2 technology.com> wrote in message
news:uajlgjo...@corp.supernews.com...
Robert L Bass
remove the wires. It's also a potential lethal hazard. If the wiring in
the duct burns during a fire it can fill the air supply with toxic fumes --
not so good.
Regards,
Robert L Bass
=============================>
Bass Home Electronics
The Online DIY Alarm Store
http://www.Bass-Home.com
2291 Pine View Circle
Sarasota, FL 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
rober...@comcast.net
=============================>
"wert" <we...@home.com> wrote in message
news:3lfiau4j49qikilvd...@4ax.com...
Chris
because I did it on a Sunday when nobody was working and crossed my
fingers that nobody would say anything and sure enough they
didn't...Makes me mad too because I always thought that when I would
build a house I would wire the crap out of it..well I still have those
plans..unfortunatly I get to retrofit again...yeah....
The house is already done..so I get to deal with conduit I've installed
and thats it...I was thinking about cutting some new holes in the
drywall and drilling top and bottom on main level to run either new
conduit (if possible) or just drilling for running wire...anybody have
any experience doing this?
--
"A democracy is not a form of government to survive. For it will only
succeed until its' citizens discover they can vote themselves money from
the treasury, then they will bankrupt it." -Karl Marx
Joe Greco
:No, that was all I *could* do was run 2 2" conduits....and that was only
:fingers that nobody would say anything and sure enough they
Well, that's a pretty good amount of capacity. Think carefully about how
much capacity you really need.
One thing I'll point out is that sometimes people try to run individual
cables through conduit. It works, but after a dozen or so, the potential
for tangles inside the conduit is pretty high, and you get frustrated and
declare it "full". If at all possible, lay out all your cables in advance
and bundle them in one smooth, compact bunch. Don't forget to use cable
puller's grease, too, if you want it to go smoothly. You can fit a _lot_
into just one 2".
:didn't...Makes me mad too because I always thought that when I would
:build a house I would wire the crap out of it..well I still have those
:plans..unfortunatly I get to retrofit again...yeah....
:
:The house is already done..so I get to deal with conduit I've installed
:and thats it...I was thinking about cutting some new holes in the
:drywall and drilling top and bottom on main level to run either new
:conduit (if possible) or just drilling for running wire...anybody have
:any experience doing this?
Running conduit after the fact can be a bit tricky, but is pretty flexible
in the long run (geez, no puns intended).
However, to run vertical sections of conduit, you generally have to have
vertical space (because conduit is stiff). If you have space in your
basement, you may be able to get away with making a relatively small hole
in the drywall at the floor and/or ceiling on the first and second floors,
and using joiners to splice the sections together. Otherwise, you may
have to open up your wall on one of the two levels. Either way, replacing
drywall is not terribly difficult (and only a little bit harder to do a
nice job). Your wall is made of drywall that is most likely fastened down
with screws to 2x4's.
If you don't have the space in the basement and are opening the wall, the
method that works best (for repairing the drywall) is to open up one whole
space from floor to ceiling. It'll be about 16 inches wide (standard).
Cut the drywall so that half of the 2x4 is visible - the 2x4 needs to
support the surrounding drywall but also the new drywall. Drywall is very
easy to work with - most pros use a razor knife. I usually end up using
my Swiss Army knife to score it. To close up, cut a new piece of drywall
the same size as your opening, screw it down around the edges, and then
tape and mud the joints. USG has a brief but complete "how-to" guide at
http://www.usg.com/Expert_Advice/3_5_homeanswr_index.asp which covers a lot
of stuff I didn't mention. Be sure to prime the wall before painting.
Alternatively, you can build a little "cable raceway" by knocking out a
space large enough to get a drill into at the bottom and top of your
walls on both floors, and get some little wooden doors to finish the job
and leave yourself a way to access it in the future. This probably works
best inside a closet or some other place that's not too visible.
Be thankful: a new house is easiest to retrofit. It gets much more
complex once rooms get painted various colors that you can't get a match
for, when there's furniture in the way, etc. I'd still be irritated,
but the job you're having to do is not terribly difficult compared to
some I have seen.
... JG
Robert L Bass
I've been doing this sort of thing for a quarter of a century. If you want
to dialogue with me a bit, I'll be happy to share what little I know. :*)
Before you start cutting into sheetrock, do yourself a favor and let's chat.
Most of the time you can use the device you want to mount as a starting
place for a long, flexible shaft drill bit (popular brands: D;Versi Bit and
Canadian Flexi Drill; *not* Labor Saving Devices).
With a little planning you can probably do the whole job with almost no need
for spackle.
Regards,
Robert L Bass
=============================>
Bass Home Electronics
The Online DIY Alarm Store
http://www.Bass-Home.com
2291 Pine View Circle
Sarasota, FL 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
rober...@comcast.net
=============================>
Chris wrote:
>
> No, that was all I *could* do was run 2 2" conduits....and that was only
...
previous^@hotmail.com seismo
was built and have yet to fill up the first one. A boat load will fit in
these two conduits. I'd only break into sheet rock after filling the two.
I also figure over the years some wiring may get decommissioned and replaced
with newer technology. When this happens I'll just yank the old stuff out
and make room in existing conduits again. Had some HVAC folks in my house
recently eyeing my unused conduit to run PEX tubing up to the attic. I told
them to keep out and look elsewhere.
"Joe Greco" <jgr...@ns.sol.net> wrote in message
news:3cab77e9$0$3114$39de...@news.sol.net...
Robert L Bass
Also, many people like to home run all of their CAT5 for the LAN to the
wiring closet. However, you can save space in the conduit by installing a
remote hub or switch in a 2nd floor closet -- *not* the attic. Run all the
2nd floor PC cables there and ruin one CAT5 from there back to the wiring
closet in the basement.
I did this when I built a new office in my old home. It was a royal pain
fishing cable across the finished ceiling in the home theater to reach the
office on the other side. I got fed up after pulling the first two CAT5
runs to an outlet (phone/PC) in the office. I put a switch in the office,
ran a short CAT5 patch cable from the outlet to the switch and connected the
other two PC's and a print server to the switch.
You can do something similar with remote sensors for the security /
automation system. Most of the better quality systems are "distributed" --
that is, you can attach a small multi-port module to the 4-wire data buss
anywhere in the house. Then you can connect a group (usually 8) of sensors
to the module. Only one or two cables need to go back to the master control
panel in the basement.
Unfortunately, most key telephone systems don't have anything like this.
Regards,
Robert L Bass
=============================>
Bass Home Electronics
The Online DIY Alarm Store
http://www.Bass-Home.com
2291 Pine View Circle
Sarasota, FL 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
rober...@comcast.net
=============================>
Joe Greco wrote:
>
> --- snip a bunch of good stuff ---
Malcolm W
> No. Don't run thermostat wire inside the duct either.
I have a central chimney chase that is just LOADED with all my low voltage
stuff. It's perfect because the wire room is right under it and there was
plenty of extra room. I'll post the web site for pictures soon.
On the left side of the chase on the first floor is the thermostat and below
that is a return. Lots of wires and space in the cavity behind the return.
What do the HVAC installers do? Punch the wire right down through the
return instead of behind it. Sheesh.
Robert L Bass
Been there... done that. I was about to mention running cables next to the
chimney. It and the DWV are often easy to fish.
One tool (if you can call it that) which I found very useful is a huge
length of beaded chain. Many years ago I came across a shoe box full of the
stuff at a garage sale. The guy wanted $5 for the box. It was all tangled,
but I managed to get about 30-50 feet of it unsnarled. I used to drop the
stuff down the chimney or DWV chases in old homes from the attic. The
beaded chain rolls over snags and obstructions, almost invariably finding
it's way to the basement without the need for cutting a new hole.
I would connect a single 22/4 wire to the chain in the cellar and pull it
back up to the attic. That became my pull wire to draw whatever needed to
go up to the attic.
Every so often there'd be a snag and I'd lose a few feet of chain in the
wall. But there was so much more in that shoe box that I never ran out. I
think I had that stuff for better than 20 years. It's gone now with the
divorce, along with my good power tools... :(
--
Regards,
Robert L Bass
=============================>
Bass Home Electronics
The Online DIY Alarm Store
http://www.Bass-Home.com
2291 Pine View Circle
Sarasota, FL 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
rober...@comcast.net
=============================>
"Malcolm W" <wari...@sunSPlinkAM.net> wrote in message
news:a8hsa6$d6f$1...@inntp-m1.news.aol.com...
Joe Greco
:Don't let the copper exceed 40% of the cmil area of the conduit.
While NFPA 70 348.22 might appear to require the use of the percentage
fill table, which basically says 40% for all useful cases, most inspectors
realize that the purpose of the NEC is to prevent fires and hazardous
conditions, and that most low-voltage wiring presents very minimal risk in
this regard. I would guess that most inspectors would prefer to see your
cable in conduit, since conduit protects the cable from damage and
simultaneously protects the surroundings from your cable, even in the
case where more than 40% was in use.
Further, the NEC itself supports that general viewpoint, as one of the
notes to the fill table mentions that the table is not intended to apply
to /sections/ of conduit used to protect exposed wiring from physical
damage, but rather complete conduit systems. And the poster was clearly
talking about sections, although perhaps not exposed :-)
Finally, I'm pretty sure that NFPA 70 800.48, which talks about raceways
for communications wires and cables, specifically exempts these raceways
from conduit fill restrictions. I don't have a PDF of Chapter 8 for some
reason though, so I can't actually check. But I also believe that this
section applies to things like alarm systems as well, even though they do
have low-voltage power and are not simply "communications".
So if that's the case, forget the 40% rule. Maybe somebody with a copy
of the 2002 NEC can look it up to clarify...
Regardless, you still have to reserve some percentage of the conduit to
avoid damage to the cables while pulling, of course.
And you really should check with your electrical inspector anyways, to see
if s/he has any specific concerns or pet peeves. Talking with a pro
almost always results in useful information, and may save headaches in the
long run.
... JG
Robert L Bass
stick with 348.22.
1) If the inspector is a PITA, you have not given him an excuse to bust your
job.
2) Although *most* of our low voltage work is inherently safe, some is not.
Even some which seems OK can turn out to be a problem. For example, we
sometimes find folks running speaker cables in conduit along with LAN and
other goodies. It's not a problem for the speakers since they won't
transmit any inducted noise at perceptible levels. But speaker cables can
end up carrying very high amperage loads. I've seen at least one home-made
speaker selector do the China Syndrome thing. It smoked and then melted.
Joe Greco> wrote:
>
> Robert L Bass <rober...@comcast.net> wrote:
>> Don't let the copper exceed 40% of the cmil area of the conduit.
>
> While NFPA 70 348.22 might appear to require the use of the percentage
> fill table, which basically says 40% for all useful cases, most inspectors
> realize that the purpose of the NEC is to prevent fires and hazardous
> conditions, and that most low-voltage wiring presents very minimal risk in
> this regard. I would guess that most inspectors would prefer to see your
> cable in conduit, since conduit protects the cable from damage and
> simultaneously protects the surroundings from your cable, even in the
> case where more than 40% was in use.
>
> Further, the NEC itself supports that general viewpoint, as one of the
> notes to the fill table mentions that the table is not intended to apply
> to /sections/ of conduit used to protect exposed wiring from physical
> damage, but rather complete conduit systems. And the poster was clearly
> talking about sections, although perhaps not exposed :-)
I didn't follow the thread that carefully so I hadn't noticed that.
However, the interpretation of his purpose is subjective -- thus reverting
back to reason #1.
> Finally, I'm pretty sure that NFPA 70 800.48, which talks about raceways
> for communications wires and cables, specifically exempts these raceways
> from conduit fill restrictions.
Do you think that would apply to conduit since it's written specifically for
raceways.
> I don't have a PDF of Chapter 8 for some reason though, so I can't
> actually check. But I also believe that this section applies to things
> like alarm systems as well, even though they do have low-voltage
> power and are not simply "communications".
AFAIK, alarm cabling is also subject to the 40% fill rule. Frankly, I've
never approached 40% using alarm cables since it is so rare that I've needed
conduit for them. The only times I've had to run alarms in conduit were
when installing warehouse type fire & burglar alarms and a few commercial
fire alarms in apartment buildings. In the former, the conduit was for
physical protection (fire alarm cables susceptible to physical damage are
required to be protected) and there your comment about the exception would
certainly apply. But these were typically a single 18/4 cable in a 1"
conduit -- well under 40% fill. It was never an issue. I've always tried
toi stay way ahead of what the inspector might want. Only once in my
carreer have I had an inspector who simply would not be placated. He was
the only fire marshal I ever bucked, too. I sent a letter to the state fire
marshal and got a ruling. Fortunately, I didn't need to work in that town
too often. The guy was bad news.
> So if that's the case, forget the 40% rule. Maybe somebody with a copy
> of the 2002 NEC can look it up to clarify...
Note: "The application and interpretation of this code shall be subject to
the discretion of t6he Authority Having Jurisdiction." (caps mine)
> Regardless, you still have to reserve some percentage of the conduit to
> avoid damage to the cables while pulling, of course.
>
> And you really should check with your electrical inspector anyways, to see
> if s/he has any specific concerns or pet peeves.
Absolutely! Since the one over-riding rule is the one in my last paragraph
above, you owe it to yourself to check first.
> Talking with a pro almost always results in useful information,
> and may save headaches in the long run.
If by "pro" you mean someone in the trade, ummm.... well... er..., I guess
I might qualify. :*) If you mean the inspector, suffice it to say that I
regularly talk to them, especially if I have a question concerning what they
may or may not like. It saves me a lot of grief.
Always a pleasure, Joe.
Joe Greco
:I don't dispute what you're saying, Joe. However, there are two reasons to
:stick with 348.22.
:1) If the inspector is a PITA, you have not given him an excuse to bust your
:job.
If the inspector is a PITA, the mere fact that you put it in conduit at all
is generally a Big Sign to him that you're doing it better than the next
guy.
:2) Although *most* of our low voltage work is inherently safe, some is not.
:Even some which seems OK can turn out to be a problem. For example, we
:sometimes find folks running speaker cables in conduit along with LAN and
:other goodies. It's not a problem for the speakers since they won't
:transmit any inducted noise at perceptible levels. But speaker cables can
:end up carrying very high amperage loads. I've seen at least one home-made
:speaker selector do the China Syndrome thing. It smoked and then melted.
:-)
:Joe Greco> wrote:
:>
:> Robert L Bass <rober...@comcast.net> wrote:
:>> Don't let the copper exceed 40% of the cmil area of the conduit.
:>
:> While NFPA 70 348.22 might appear to require the use of the percentage
:> fill table, which basically says 40% for all useful cases, most inspectors
:> realize that the purpose of the NEC is to prevent fires and hazardous
:> conditions, and that most low-voltage wiring presents very minimal risk in
:> this regard. I would guess that most inspectors would prefer to see your
:> cable in conduit, since conduit protects the cable from damage and
:> simultaneously protects the surroundings from your cable, even in the
:> case where more than 40% was in use.
:>
:> Further, the NEC itself supports that general viewpoint, as one of the
:> notes to the fill table mentions that the table is not intended to apply
:> to /sections/ of conduit used to protect exposed wiring from physical
:> damage, but rather complete conduit systems. And the poster was clearly
:> talking about sections, although perhaps not exposed :-)
:
:I didn't follow the thread that carefully so I hadn't noticed that.
:However, the interpretation of his purpose is subjective -- thus reverting
:back to reason #1.
:
:> Finally, I'm pretty sure that NFPA 70 800.48, which talks about raceways
:> for communications wires and cables, specifically exempts these raceways
:> from conduit fill restrictions.
:
:Do you think that would apply to conduit since it's written specifically for
:raceways.
Um.... what... exactly... do you think conduit IS? See Article 100,
definitions:
Raceway. An enclosed channel of metal or nonmetallic materials designed
expressly for holding wires, cables, or busbars, with additional functions
as permitted in this Code. Raceways include, but are not limited to,
[...] electrical metallic tubing[...]
EMT is what most people traditionally think of as "conduit". But all the
other alternatives I can think of are also covered.
And I just verified, that in the draft 2002 NEC that 800.48 DOES exempt.
I don't know that it made it into the final, though.
:> I don't have a PDF of Chapter 8 for some reason though, so I can't
:> actually check. But I also believe that this section applies to things
:> like alarm systems as well, even though they do have low-voltage
:> power and are not simply "communications".
:
:AFAIK, alarm cabling is also subject to the 40% fill rule. Frankly, I've
:never approached 40% using alarm cables since it is so rare that I've needed
:conduit for them. The only times I've had to run alarms in conduit were
:when installing warehouse type fire & burglar alarms and a few commercial
:fire alarms in apartment buildings. In the former, the conduit was for
:physical protection (fire alarm cables susceptible to physical damage are
:required to be protected) and there your comment about the exception would
:certainly apply. But these were typically a single 18/4 cable in a 1"
:conduit -- well under 40% fill. It was never an issue. I've always tried
:toi stay way ahead of what the inspector might want. Only once in my
:carreer have I had an inspector who simply would not be placated. He was
:the only fire marshal I ever bucked, too. I sent a letter to the state fire
:marshal and got a ruling. Fortunately, I didn't need to work in that town
:too often. The guy was bad news.
Yeah, I'm not saying it's a bad idea :-) I'm actually looking at this and
it isn't clear to me where exactly alarm cabling falls. Fire is quite
clear, and certainly protecting them makes a good amount of sense anyways.
Communications (which is what I do) is equally clear, and it unambiguously
is not required.
That said, 40% fill is a good guideline in any case, 'cause it gets real
tough to pull otherwise.
:> So if that's the case, forget the 40% rule. Maybe somebody with a copy
:> of the 2002 NEC can look it up to clarify...
:
:Note: "The application and interpretation of this code shall be subject to
:the discretion of t6he Authority Having Jurisdiction." (caps mine)
Well, that's always the case. However, the point is that they cannot
point to NEC and claim you're violating it, because the NEC does not leave
a lot of stuff up to "interpretation". NEC lists specific types of cable,
specific cases, etc., and you can trivially make sure that you're not in
violation of the myriad points by using the correct wire, following good
practices, etc.
They can still say that it's not allowable in their jurisdiction, and that
is fine, but it suggests that they're simply being a jerk. Especially
since this /is/ low-voltage stuff we're talking about.
... JG
Robert L Bass
> In comp.home.automation article
<3Iku8.39094$K5.36...@bin5.nnrp.aus1.giganews.com>, "Robert L Bass"
<rober...@comcast.net> wrote:
> :I don't dispute what you're saying, Joe. However, there are two reasons
to
> :stick with 348.22.
> :1) If the inspector is a PITA, you have not given him an excuse to bust
your
> :job.
Hmm. Didn't someone else write the above?
Dang it. You're right. Next time I'll think a bit longer before posting.
> Yeah, I'm not saying it's a bad idea :-) I'm actually looking at this and
> it isn't clear to me where exactly alarm cabling falls. Fire is quite
> clear, and certainly protecting them makes a good amount of sense anyways.
> Communications (which is what I do) is equally clear, and it unambiguously
> is not required.
>
> That said, 40% fill is a good guideline in any case, 'cause it gets real
> tough to pull otherwise.
Yup.
> :> So if that's the case, forget the 40% rule. Maybe somebody with a copy
> :> of the 2002 NEC can look it up to clarify...
> :
> :Note: "The application and interpretation of this code shall be subject
to
> :the discretion of t6he Authority Having Jurisdiction." (caps mine)
>
> Well, that's always the case. However, the point is that they cannot
> point to NEC and claim you're violating it, because the NEC does not leave
> a lot of stuff up to "interpretation". NEC lists specific types of cable,
> specific cases, etc., and you can trivially make sure that you're not in
> violation of the myriad points by using the correct wire, following good
> practices, etc.
Yes, you can. But I've also run into one or two really nasty AHJ's in my
time. Only once did I go to the State Fire Marshal. That's a sure way to
win the battle and lose the way if you ever plan to work in that town again.
> They can still say that it's not allowable in their jurisdiction, and that
> is fine, but it suggests that they're simply being a jerk...
Uh, yeah. Exactly. But they can be a jerk and we still lose. Best bet...
ask in advance and follow code to the letter. :^)
> Especially since this /is/ low-voltage stuff we're talking about.
Been there and done that. Many inspectors are just as rigorous with low
voltage as high, particularly when it involves life safety (I do lots of
fire alarms and run into it all the time). I've rarely had to redo anything
though because I've always been a stickler for code. The one major
exception was that one FM I mentioned earlier -- what a pain he was!
--
Joe Greco
:"Joe Greco" <jgr...@ns.sol.net> wrote in message
:news:3ccd9be5$0$3342$39de...@news.sol.net...
:> In comp.home.automation article
:<3Iku8.39094$K5.36...@bin5.nnrp.aus1.giganews.com>, "Robert L Bass"
:<rober...@comcast.net> wrote:
:> :I don't dispute what you're saying, Joe. However, there are two reasons
:to
:> :stick with 348.22.
:> :1) If the inspector is a PITA, you have not given him an excuse to bust
:your
:> :job.
:
:Hmm. Didn't someone else write the above?
It appears to be quoting you.
:> :Do you think that would apply to conduit since it's written specifically
:for
:> :raceways.
:>
:> Um.... what... exactly... do you think conduit IS? See Article 100,
:> definitions:
:
:Dang it. You're right. Next time I'll think a bit longer before posting.
Grin :-)
:> :> So if that's the case, forget the 40% rule. Maybe somebody with a copy
:> :> of the 2002 NEC can look it up to clarify...
:> :
:> :Note: "The application and interpretation of this code shall be subject
:to
:> :the discretion of t6he Authority Having Jurisdiction." (caps mine)
:>
:> Well, that's always the case. However, the point is that they cannot
:> point to NEC and claim you're violating it, because the NEC does not leave
:> a lot of stuff up to "interpretation". NEC lists specific types of cable,
:> specific cases, etc., and you can trivially make sure that you're not in
:> violation of the myriad points by using the correct wire, following good
:> practices, etc.
:
:Yes, you can. But I've also run into one or two really nasty AHJ's in my
:time. Only once did I go to the State Fire Marshal. That's a sure way to
:win the battle and lose the way if you ever plan to work in that town again.
There are other alternatives. You can manage to put somebody in the wrong
quite nicely by asking an appropriate set of questions, such that they put
themselves in the wrong, without actually appearing to be attempting to
corner them. :-)
:> They can still say that it's not allowable in their jurisdiction, and that
:> is fine, but it suggests that they're simply being a jerk...
:
:Uh, yeah. Exactly. But they can be a jerk and we still lose. Best bet...
:ask in advance and follow code to the letter. :^)
Well, the latter part is the _point_ - if you follow code to the letter
and they whine, then there's a problem.
:> Especially since this /is/ low-voltage stuff we're talking about.
:
:Been there and done that. Many inspectors are just as rigorous with low
:voltage as high, particularly when it involves life safety (I do lots of
:fire alarms and run into it all the time). I've rarely had to redo anything
:though because I've always been a stickler for code. The one major
:exception was that one FM I mentioned earlier -- what a pain he was!
Fire alarm is a completely different beast, very different rules exist to
cover it, and with good reason.
... JG
Robert L Bass
"Joe Greco" <jgr...@terminus.sol.net> wrote in message
news:3ccf10ff$0$3569$39de...@news.sol.net...
> In comp.home.automation article
<MNnz8.225753$3L2.20...@bin7.nnrp.aus1.giganews.com>, "Robert L Bass"
<rober...@comcast.net> wrote:
> :"Joe Greco" <jgr...@ns.sol.net> wrote in message
> :news:3ccd9be5$0$3342$39de...@news.sol.net...
> :> In comp.home.automation article
> :<3Iku8.39094$K5.36...@bin5.nnrp.aus1.giganews.com>, "Robert L Bass"
> :<rober...@comcast.net> wrote:
> :> :I don't dispute what you're saying, Joe. However, there are two
reasons
> :to
> :> :stick with 348.22.
> :> :1) If the inspector is a PITA, you have not given him an excuse to
bust
> :your
> :> :job.
> :
> :Hmm. Didn't someone else write the above?
>
> It appears to be quoting you.
I must be getting old. I don't remember writing that. :)
> :> :Do you think that would apply to conduit since it's written
specifically
> :for
> :> :raceways.
> :>
> :> Um.... what... exactly... do you think conduit IS? See Article 100,
> :> definitions:
> :
> :Dang it. You're right. Next time I'll think a bit longer before
posting.
>
> Grin :-)
<smirk>
True.
> :> Especially since this /is/ low-voltage stuff we're talking about.
> :
> :Been there and done that. Many inspectors are just as rigorous with low
> :voltage as high, particularly when it involves life safety (I do lots of
> :fire alarms and run into it all the time). I've rarely had to redo
anything
> :though because I've always been a stickler for code. The one major
> :exception was that one FM I mentioned earlier -- what a pain he was!
>
> Fire alarm is a completely different beast, very different rules exist to
> cover it, and with good reason.
Something about potential for loss of multiple lives as I recall (uh, one
per person, that is).