EMT Requirement in Chicago

[texie]

Of the 6 or so houses I owned over the years there I think 3 were old enough to be piped. One of them built in the early 70s was piped with AL conductors. When I bought it in the early 80s of course by then the old AL wiring was a known issue. It was a cinch to just pull all new THHN CU and replace all the AL. In those days there was not as much cheating and hack work, so as long as some hack did not remodel it you could count on things being correct behind the walls which made rewiring or remodeling a breeze.

 

[ramsy]

No j-boxes would be allowed in this enclosed space so everything has to be up and down to outlets.

Lots of existing apartments in CA were built with flex conduit. 4S J-box & P-ring behind plugs & switches.

Those junctions are no longer used by property mgrs., who avoid qualified persons that can connect to building departments, and constructively evict tenants who may have family fire-department personnel.

Property mgmt. uses laborers, not JW's, nor qualified apprentices. So any invoicee --with GL Policy-- becomes a matter of record for that property, however finished by the laborers.

 

[hillbilly1]

I think you are allowed to fish Romex if it's a repair or remodel job and it's impractical to do EMT.

I would think they would have fished BX or MC cable (later years) BX was preferred by the Unions down here to be competitive with the open shops.

 

[don_resqcapt19]

How is EMT run in wood framed single family homes? Seems like running horizontal through studs would be difficult. Is every outlet dropped from the attic? Are all houses built with open web beams between floors? No j-boxes would be allowed in this enclosed space so everything has to be up and down to outlets. How much does all this EMT add to the price of a house? Inquiring minds want to know.

There are lots tricks to "pipe" a wood framed house. The construction of the house itself is no different from any other house. In areas where the walls are not structural, you can notch the stub, but I have never seen that done.
In my area we require EMT where there is over 4 dwelling units in a single building.
It is not that difficult to install the EMT. It is typically 1/2" and with a 1.25" hole in the center of the studs you can slide the conduit in with studs on 16" centers. If there is a door opening close by, you would start the horizontal run of holes at the door to make it even easier.

While most here will not believe, the cost of EMT over NM, where the EMT is being installed by a contractor that noramally does that type of construction, the us of EMT over NM will add 7-15% to the total electrical cost for the dwelling unit. If you have never done it before and try it, you will add 50% or more to the costs. How things are laid out is totally different between an NM job and an EMT job.

The reverse can be true too. I did an inspection for some single family units in my area, while filling in for the normal inspector, and a contractor was using EMT where our code permits NM. I asked him about it, and he told me he works mostly in areas where EMT is required, and he did not think his guys could be cost effective if he switched to NM for the units he was doing in our city. The project was a hard money bid project, and he had a lower cost than other contractors who had bid the project using NM.

 

[don_resqcapt19]

I've always been under the impression the requirement was based on fire concerns.

I believe it is based on rodent damage to the NM, but that does not explain their very limited permitted use of AC or MC.

 

[don_resqcapt19]

I think you are allowed to fish Romex if it's a repair or remodel job and it's impractical to do EMT.

Their 334.10 says:

Uses Permitted. Type NM and Type NMC cables shall be permitted to be used in the following:
(1) Temporary wiring for branch circuits as permitted in 590.4(C)
(2) Temporary wiring as permitted for feeders as permitted in 590.4(B)
(3) Limited extensions to knob-and-tube lighting or appliance branch circuits in existing dwelling units in buildings not exceeding three stories in height.”{/quote]

Their .10 sections for 320 and 330 read:

“Uses Permitted.
(A) Existing Installations. Except where otherwise specified in this Code and where not subject to physical damage, listed Type MC cable with listed fittings and not exceeding 7.62 m (25 ft) in length between junction boxes shall be permitted for branch circuits in concealed work fished into existing walls, partitions, floors, or hard surface ceilings where other work does not require or include removal of the existing finished surface.
(B) Exposed Work. For exposed work only under the following conditions:
(1) In lengths not more than 1.83 m (6 ft), at terminations where flexibility is necessary;
(2) In lengths not greater than 1.83 m (6 ft) in accessible, but not habitable, attics and roof spaces where installed in accordance with 320.23;
(3) In lengths not greater than 1.83 m (6 ft), below the basement ceiling joists where it is necessary to connect a cabinet or junction box.”

In all 3 cases their .12 sections say that an installation not specifically permitted in the .10 sections is prohibited.