Conduit question

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Old 05-13-03, 09:11 PM
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Conduit question

Hi again

I've started laying out my conduit in my basement project. Since I'm working in my basement, I am running a lot of conduit overhead on the joists. The problem is, when they built my house, the builders also ran lots of conduit along the bottom of my joists, along with a gas line and of course heat/air conditioning ducting.

1) Are they are any rules per building code that require my conduit be a certain distance away from existing conduit, ducting, or gas pipes? Can my conduit physically touch any or all of the above? My roughed in empty conduit is currently touching all 3 in one place or another!

2) How often do lengths, bends, and junctions of conduit have to be supported? What can be used, by code, to support conduit besides those J shaped metal hangars that you hammer into the bottom of a joist?

3) Is there a limit, either by code or practicality, as to how many wires are allowed to be twisted together under a cap with one hot wire feeding the others? All of my wiring is of the gauge corresponding to 20A circuitry.

Thanks for your time,
Steve
 
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Old 05-14-03, 06:19 PM
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#1 Your Conduit can touch all of the above (except disimmilar metals ie. copper waterlines the steel and the copper work against eachother and one if not both will be eaten through) I will also caution against touching heating ducts as the conduit and duct may rattle when furnace runs and wouldn't that be fun around 2 am.

#2 Conduit must be secured every 10' and within 3' of every box or coupling. When a conduit passes through a framing member it is considered secured however it is good pracice to secure it anyways to stop rattling. There are several methods and devices for strapping pipe J-nails are the most common because they are cheap easy and inexpensive. J nails are good for straping pipe that passes through studs they can be driven into the hole essentially toenail the pipe in place. One hole and two hole straps are more suited for exposed or surface mounted work. They snap on to the conduit and a screw or nail is driven into the hole or holes.

#3 The limit on the number of conductors is not limited by the code but by the wirenuts themselves. each color represents their size. So check the package and there is a table that lists the size and number of wires and purchass the ones that are appropriate for you.
 
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Old 05-15-03, 08:15 PM
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Thanks Sparky for your help!
 
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Old 05-16-03, 08:10 PM
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P Michael
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Ualdriver,
First a comment about contractor who "ran lots of conduit along the bottom of my joists". If they ran their pipes perpendicular to the joists, they probably didn't have much choice. But it sounds as if they ran them parallel to the joists, that is underneath the joists, and in this situation, this is a dumb mistake. Since now you want to run some new stuff perpendicular to the joists and you have to bridge or saddle over [under?] them. They should have been run on the sides of the joists about 1 1/2" up from the edge.

2) Sparky seems to have answered your other questions. But I would like to add that there are several other devices to support conduit. There is something called a "conduit hanger" - also known as a "Mini" - which looks like a "U" shaped piece of sheet metal which is all bent up. There is a hole at the bottom of the "U" to screw it to whatever and a bolt at the top to squeeze it around your conduit. [Google for the Mineralac site]
Also there is the UniStrut system which uses Uni-Strut clamps.

3) You should be advised not to EVER use nails to install one or two hole straps or anything else for that matter. Screws have now been invented.

~Peter
 
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Old 05-17-03, 07:06 AM
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Another quick question. Sparky mentioned that conduit shouldn't touch "dissimilar metals." Since my conduit is criss-crossing lots of other ducting, piping, etc., there is one area where my conduit is touching the gas pipe feeding my laundry room and kitchen. Is the gas pipe and conduit piping of dissimilar metal? And if they are and they are touching, what does code require me to do to put a space between them as I have no choice but for them to cross? Same with copper water pipe. If eventually they criss-cross and this is unavoidable, what should I do to keep them from touching and meet code?

Thanks,
Steve
 
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Old 05-17-03, 09:41 AM
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The gas pipe and your conduit are usually both steel so they're both the same.However you could increase the size of your offsets, bridges and saddles to achieve a little bit of space - like 1/4".
The copper water pipe is an obvious no-no. A common field solution is to wrap one or both pipes with electrical tape or duct tape in the area where they might rub.
One advantage of the conduit hanger or Minnie is that it can be hung from a length of all-thread. Thus your conduit can run several inches below the bottom of the joists and cleareverything.
Have fun.
~Peter
 
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Old 05-17-03, 12:21 PM
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Thanks P Michael. More questions to follow............ : )
 
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Old 05-19-03, 09:48 PM
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be sure the suburb you are in doesn't have amendments to the nec that make it more closely follow chicago's code. for example, while the nec allows emt to be supported every 10', chicago requires 7'. many suburbs do not allow romex, like chicago. in elgin, all outside, exposed (not undergorund) wiring MUST be in rigid, threaded conduit - nothing else. call your local building dept and ask.
john
 
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Old 05-20-03, 08:14 PM
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Thanks John. I'm up in Lake in the Hills (LITH) and they gave me a separate LITH "special rules" sheet and I didn't see any mention of that. I'll look into it though.

Steve
 
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