House wiring in emt?

[zoltrix717]

I've heard that some house wiring (new) methods is to be done in conduit / EMT. Is this true in some places in the states? I'm from Canada and all house wiring here is done in NMD. Also are some house done in BX? I'm wondering what is the ratinonale behind this. Conduit seems awfully expensive way to wire a house, and BX, that would be expensive as well. Where are these methods done in the states?

 

[tom baker]

Re: House wiring in emt?

Chicago requires emt wiring methods. NM is the most common but the uses allowed varies by location, state, county or city.

 

[roger]

Re: House wiring in emt?

I have heard this is the case in the Chicago area. A member from that area will let you know soon.

Roger

 

[ryan_618]

Re: House wiring in emt?

Chicago has been involved with some very serious code issues in its decorated history. For example the very large fire that initiated the need for building codes and also the VERY large dysentary epidemic that at one time had 1/3 of the population dead or near it from plumbing cross-contamination. I wonder if they are just gun-shy from their unfortunate history...

 

[dereckbc]

Re: House wiring in emt?

Can't speak for Chicago, but in my area if you use metal framming you are required to use EMT, also most insurance companies have discounts if you use EMT in residential.

 

[Guest]

Re: House wiring in emt?

Originally posted by zoltrix717:
<snip> Also are some house done in BX? I'm wondering what is the ratinonale behind this. <snip>

There are some local AHJ's that require runs in crawl spaces to be protected. Mostly it's done with AC ("BX"). These are pretty old rules that may go back to rat-proofing of crawl spaces. The rat-proofing tactics have been relaxed over the years as the rat population is down, but many areas still like to be ratproofed.

I have not run into a local AHJ that required pipe or armor within the walls of dwellings. I will be interested in hearing the other posts from around the country about the where, how, and why.

[Edit add after Dereck's post: I've done several metal frame houses locally that only required NM. Not sure about other local AHJ's policy on that].

[ October 23, 2003, 10:47 PM: Message edited by: awwt ]

 

[zoltrix717]

Re: House wiring in emt?

Alright. If a house is wired in emt, how exactly is it done. A lot of extra j-boxes I guess. Does the pipe run all to one box or is there mutiple runs of 1/2 or 3/4 coming out the panel. What is wrong with NMD where emt is required? and if NMD is not allow does that when there is not use for NMD at in that state?

 

[hbiss]

Re: House wiring in emt?

Depends on the house construction and layout but it would be done like many commercial jobs. Sounds like you never saw a building with everything run in EMT before.

Many houses built before the 60's around here were wired with BX. As a matter of fact my own house is done that way and although I certainly use NM, any changes and additions I do around here I do with AC. And, no, I've never seen a rat.

 

[wolfman56]

Re: House wiring in emt?

OK guys I'm from the Chicagoland area. Until I moved to Washington state 3 yrs. ago, I had NEVER touched Romex! Chicago, and almost all AHJ's for about 70 miles around pretty much demand all emt. I was weaned on emt, and kinda miss it. And no there are not any extra J-Boxes. In fact the runs are simpler. look at it this way. A 1/2" pipe can hold up to 9 #14 wires without being concerned about derating, so 1 run of pipe can have the equivelent of several romexes in it. In homes you mostly use 1/2", except for of course the large stuff like an AC run. Personally I think pipe is way better, and it's great doing remodels or repairs where originally done in pipe.

 

[flightline]

Re: House wiring in emt?

As both en electrician, licensed in Chicago, and as an inspector in one of the adjacent suburbs, most of what has been said is accurate.. Most runs these days are 1/2 for everything. It is our generally our equipment grounding conductor as well. Most boxes are 1900 side bracket style. Only ceiling fan boxes or a couple of 8b boxes on slide brackets are the bill of faire.

Coming from where I was, Romex or NM was the rarity.

A good "flatting" crew, 1 or maybe 2 guys can quickly drill, box and pipe a house in a couple of days for a standard "tract" home. Pulling individual THHN conductors goes quickly. A nice side benefit is that you can usually pull another circuit or switch leg through the runs to add circuits, or make modifications easily, or at least with minimal damage.

For services, it's GRC, IMC. Aluminum rigid, or in some older areas, although this is getting more and more limited, SE cable.

With respect to speed, I don't remember what the percentages are, but I do know that, since that's all we do, we're pretty quick.

We too have a code specific to our area, but around 2000, it was based upon the 1999 NEC, and has been updated as the new codes came out. We publish yearly, but they fine tune it each year. It is the code I would like to move to i my town, as it limits some of the things that got left out in ammendments.

I hope that this is what you are looking for as an answer.

 

[iwire]

Re: House wiring in emt?

Originally posted by hbiss:
Depends on the house construction and layout but it would be done like many commercial jobs. Sounds like you never saw a building with everything run in EMT before.

I have piped many commercial buildings and I feel I am fast and neat.

I think it would take me a long time to pipe a dwelling, keeping in mind I can not run a 2" and drop J box's above the ceiling where ever I want.

 

[wayne123]

Re: House wiring in emt?

This may sound stupid but, how do you run the conduit through the wood studs? wouldn't that require alot of pipe cutting and alot of couplings. I have done several commercial jobs in emt and it's not that difficult to run emt through metal studs because you can twist the stud enough to get a full stick of 1/2" emt through the pre-punched holes. Also isn't kind of time consuming trying to line up all of the drilled holes in order to thread the conduit through it?

 

[brian john]

Re: House wiring in emt?

I was told by a Union electrician fron Ill. that this was the way it is and THAT IS THEY WAY WE ARE GOING TO KEEP IT.

Not sure if this is a Union issue but his reply to my question sure made it seem that way.

 

[flightline]

Re: House wiring in emt?

To Wayne,
Since most residences will have some sort of attic and basement space here, we basically make a number of tall hooks in the pipe for running on top of ceiling joists, and drop into the basement with short versions running the bottoms of the floor joists. It's really easy to pull that way too. There are some instances in which drilling the studs cannot be avoided, and then you are correct, some time is lost. Connections from one wall to lets say another opposite can be done by jumping into the joist space and running between, than dropping down to where you have to be. One thing that we look for when inspecting is strapping. You would think that the nail-its were made of gold. You wouldn't want to have someone's new home, irrespective of cost, have pipes rattling in the walls when a truck went by or someone shut an interior door a little harder than ususal.

I've got to believe that we have gotten as good as putting in pipe as proficiently as those of you who flat in NM. If it's all you do, then, hopefully, you get good at it.

The apprentices even have a full size house frame in our school that they must pipe and pull, and then be graded on.

 

[tonyi]

Re: House wiring in emt?

Originally posted by wayne123:
This may sound stupid but, how do you run the conduit through the wood studs? wouldn't that require alot of pipe cutting and alot of couplings. I have done several commercial jobs in emt and it's not that difficult to run emt through metal studs because you can twist the stud enough to get a full stick of 1/2" emt through the pre-punched holes. Also isn't kind of time consuming trying to line up all of the drilled holes in order to thread the conduit through it?

You try to keep long horizontal runs in the basement/attic and come up/down. For a 1 or 2 story place this works well. For 3+ you're drilling and jiggling more.

 

[hbiss]

Re: House wiring in emt?

Personally I think pipe is way better, and it's great doing remodels or repairs where originally done in pipe.
I would agree, I like pipe too, except what happens when the owner wants additional receptacles, lights, etc added? That would entail tearing the walls and ceilings up for the new runs. Big expense.
Also, how do you pipe a ceiling full of hi-hats even on a new job? Got to be a real bear running against the joists.

 

[scott moran]

Re: House wiring in emt?

As a small electrical contractor from the Chicago area, and someone who has done work in flightline's juristiction, it it no big deal to ruff a new home in EMT. There are areas that I work in that do allow romex, and I wont even touch those jobs. That requires a different mode of thinking, and like you that don't use EMT, I dont have the "mind set" for it.

There are MANY tricks to doing it and the comment was made that you can pull a number of wires in one conduit. This makes it great when your running 3 & 4 way switches that are all over the place in these custom homes.

 

[russ]

Re: House wiring in emt?

I don't know much about NM because I've never used it.
It's strange how NM is allowed to be used in your house where your family sleeps, but not used in health care facilities. There's a few other places you can't use it listed in 334.12.
If it's not going to be used everywhere, I prefer it not be used in my house. If it's the best and safest way to wire a house, then fine, no problem. I think it's cost verses safety.

 

[Guest]

Re: House wiring in emt?

I like pipe, but any electrical system can be unsafe if it's not done with care. Here's a quote about even knob-and-tube:

Knob and tube wiring is characterized by separately run hot and neutral wires, paper insulated wires, ceramic insulators and the absence of junction boxes at wire splices. If this type of wiring has been professionally maintained since its original installation, is often still a very safe system. However, ungrounded conditions, improper modifications and amateurish <snip> repairs of this type of wiring can lead to certain safety/fire issues; this is the main reason why knob and tube wiring is considered a higher risk than contemporary wiring installations.

 

[russ]

Re: House wiring in emt?

Tou Che
If thats how you spell it.