Chicago and EMT

[sparky1118]

Does anyone know the reasoning as to why they wire houses in Chicago in EMT? I am part of a different forum and some electricians from Chicago post pictures of their work and it’s all EMT in wooden stud walls. I asked them why and they said they have to do it that way. But don’t have a reasoning as to why. I was just curious


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[480sparky]

The reason is lost to history.

 

[nickelec]

Chicago fire

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[480sparky]

Um........ I doubt a fire in 1871 had anything to do with it.

I have a 1930 Chicago code book that has NM in it.

 

[sparky1118]

Um........ I doubt a fire in 1871 had anything to do with it.

I have a 1930 Chicago code book that has NM in it.

I wonder what the reasoning is.


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[norcal]

Make work reasons?

 

[tom baker]

With EMT, don't need AFCIs. AFCIs are for fire protection from damaged NM...If you run EMT in stud walls you get pretty good at running it.

 

[LarryFine]

If you run EMT in stud walls you get pretty good at running it.

That's for sure! First you learn to depend on using a lot of couplings, then you you learn how not to.

 

[480sparky]

I wonder what the reasoning is.


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My guess is, being Chicago, someone in the AHJ had a cousin in the steel industry.

 

[jaggedben]

Why don't they use flex?

With EMT, don't need AFCIs. AFCIs are for fire protection from damaged NM...If you run EMT in stud walls you get pretty good at running it.

That's not true, or at any rate it's not the way the code is written. AFCIs are required at the first outlet regardless of wiring method. I believe the intention is to protect against faults on cords and appliances on the load side of the receptacle, not just in permanent wiring.

 

[retirede]

I read where ECs and unions got this passed to minimize competition from DIYers and handymen. The payoffs made some aldermen rich.

 

[tom baker]

Why don't they use flex?



That's not true, or at any rate it's not the way the code is written. AFCIs are required at the first outlet regardless of wiring method. I believe the intention is to protect against faults on cords and appliances on the load side of the receptacle, not just in permanent wiring.

Yes that is correct. What I have heard is there is less fires in cities that don't allow NM

 

[480sparky]

Yes that is correct. What I have heard is there is less fires in cities that don't allow NM

Hush up, now.... we don't need the CMPs to find out that little secret.

 

[hbiss]

I read where ECs and unions got this passed to minimize competition from DIYers and handymen. The payoffs made some aldermen rich.

BINGO!

What I have heard is there is less fires in cities that don't allow NM

I keep saying, ban MN. If using AC or MC meant AFCIs weren't required anymore I would switch in a heartbeat.

I believe the intention is to protect against faults on cords and appliances on the load side of the receptacle,

So make manufacturers put AFCI plugs on lamps and appliances like the GFCI plugs on hair dryers.

-Hal

 

[goldstar]

Why don't they use flex?

While the vast majority of the house is done with EMT you are permitted to use AC or MC cable if you want to add say a paddle fan to an existing bedroom. FWIW, if you go to HD or other like stores you probably won't find any NM cable on the shelves.

 

[don_resqcapt19]

I read where ECs and unions got this passed to minimize competition from DIYers and handymen. The payoffs made some aldermen rich.

My comment when I see this is that you are telling me that electricians who are not in the IBEW don't know how to run conduit

 

[don_resqcapt19]

No one that I know of has found the original documentation for the Chicago "pipe rule". The most plausible is to prevent rodent damage, but things like AC and MC also prevent that.

 

[kwired]

My comment when I see this is that you are telling me that electricians who are not in the IBEW don't know how to run conduit

In some areas this is probably mostly true.

 

[kwired]

I still think it was likely contractors, unions, maybe even steel industry to some extent.

Get a group together with an intent and plenty of funds to back them and they often get what they want. Won't mention AFCI manufacturers doing anything like that, oops I just did.

 

[don_resqcapt19]

... That's not true, or at any rate it's not the way the code is written. AFCIs are required at the first outlet regardless of wiring method. I believe the intention is to protect against faults on cords and appliances on the load side of the receptacle, not just in permanent wiring.

Chicago has there own code. The current version of the Chicago Electrical code is the 2018. It is a highly revised version of the 2017 NEC. They used about 150 pages of amendments to change the 2017 NEC into the 2018 Chicago Electrical Code.
One of those amendments is Exception #1 to 210.12(A), (B), and (C).

Exception No. 1 to 210.12(A), (B), and (C): It shall be permitted to omit AFCI protection for that portion of the branch circuit enclosed in rigid metal conduit (RMC), intermediate metal conduit (IMC), electrical metal tubing (EMT), or Type MI cable sheath meeting the requirements of 250.118 along with metal outlet and junction boxes.

Since the general rule requires dwelling units to be wired using EMT, they don't need AFCIs.
No idea where or why anyone would ever use MI cable in a dwelling unit