commercial wiring

[nizak]

I have a commercial job (complete rewire with exposed ceiling and wall access -wood construction, to be covered with 5/8" drywall) and the code allows me to wire it with NM cable. Just curious how many contractors out there still use metal cable and emt when they do "commercial" work. When I started doing electrical work years back, the Co. I worked for always treated commercial work differently than residential, we never pulled romex period. In the recent past I still run into local EC's who do it all in metal. The only problem I forsee is getting the home runs into the panel since it's surface mounted on a block wall and if I used a conduit stub as a sleeve it would be muchlonger than the 24" allowance and derating would play a factor. Thanks.

 

[BryanMD]

Just curious how many contractors out there still use metal cable and emt when they do "commercial" work.

The only problem I forsee is getting the home runs into the panel since it's surface mounted on a block wall.

Most EC's aren't the one who decides what materials or methods will be used.
The owner-designer-engineer have to be willing to spend the extra for pipe, etc.
I'd rather see all conduit too but MC (and NM when allowed) is common.

As to the home runs...
How about conduit from the panel up to a trough and land the NM there?
With a plenum ceiling no one will know. Except us

 

[peter d]

When I started doing electrical work years back, the Co. I worked for always treated commercial work differently than residential, we never pulled romex period.

Then I know right away you have never worked in New England.

 

[BAHTAH]

Commercial

Commercial

I have a commercial job (complete rewire with exposed ceiling and wall access -wood construction, to be covered with 5/8" drywall) and the code allows me to wire it with NM cable. Just curious how many contractors out there still use metal cable and emt when they do "commercial" work. .

For many years as contractors we would design and install our jobs using EMT. As time passed and with the advent of MC cable (commercial romex) competition forced some installations to go to MC. Presently we look at what type of commercial installation we are doing. Tennant improvements are an area where there are likely to be changes in the future as tennants change. We still prefer EMT as it allows for changes (additional circuits etc) using the installed EMT from the original job. We also use a combination of MC and EMT. We try to not use NMB for commerical work if at all possible.

 

[e57]

NM isn't allowed in commercial in my area - and many areas around me - so it is of little consequence.... (To me...)

NM is easier to pull and less expensive than MC - and we will now diverge from cable..... (For a moment)

For some - and the key word is some - Running conduit is second nature and pulling a number of circuits in a run can be equal or more cost effective than running cable, depending on the situation - for some it is not! It depends on a number of factors specific to each job - and the person running the job, and the person doing the work IMO...

For some putting 20 CCC's in a 1 1/4" with over-sized wire may make more sense than sticking to 9.

For some - in specific situations it may be more cost effective to run a gutter down each wall and fill it!!!!

It may also pay to use a combination of conduit/raceway and what-ever cable of choice.... Pipe off to j-boxes in various locations and cable from there.

And IMO NM would be subjected to a lot of site damage before the rock goes up - what type of gorillas are on the job?