NM-B vs. MC cable vs. EMT

[iwire]

I actually prefer conduit; it's easy to alter the conductors if you want to change something later, provided it was laid out with some forethought. Try changing wires after the fact with NM or MC.

In a non-dwelling I can usually get a new MC in faster than I can figure out how existing conduits are routed and reconfigure or snake more wires into them.


Of course there are certainly times where pipe is nice and if you happen to be an in house guy who already knows the conduit routes even more so.

I also like the fact that you don't deal with lots and lots of ground wires; the conduit is the ground, or if you like, there's one green wire in the pipe, not multiple bare conductors you have to terminate and find room for.

Here I have to agree, the multiple EGCs can be a pain. The key is to keep small ground bars on hand to use when needed.

 

[growler]

I just did an inspection (regular inspector was on vacation) for a condo where our code would have permitted NM. The contractor installed EMT because he is from the Chicago area and his guys don't know how to "rope" (slang term for installing NM in our area) a house. This was a bid job so there was no increase in costs to the owner.

I really don't see how anyone can run conduit for the same money as NM because the materials will cost more and there is no labor savings to make up for it.

 

[don_resqcapt19]

You cant say that, all the contractors could have bid it as pipe. Heck the plans likely indicated pipe.

The plans clearly permitted NM.

 

[don_resqcapt19]

I really don't see how anyone can run conduit for the same money as NM because the materials will cost more and there is no labor savings to make up for it.

In general, I agree with that, but that is not what this contractor told me when I was doing the inspection. He had no reason to tell me an untruth. Also you can only make it work with guys who install EMT in dwelling units every day. You probably get run off the job if you are installing less than a 1000 feet of EMT in an 8 hour day.

There are a number of contractors who do resi and do both NM and EMT based on the local codes. These contractors all tell me that the premium for EMT is almost always less than 15% to 20% on the electrical costs. With the electrical almost always less than 20% of the total dwelling unit cost, a 20% premium for the EMT would be less than a 1/2% increase in the total cost.

 

[Canton]

You probably get run off the job if you are installing less than a 1000 feet of EMT in an 8 hour day.

If you got a guy running over 1000' of EMT in an 8 hour day....he needs to come work for me. Couple hundred feet with bends, supports and boxes from a good pipe bender...but over 1000'? Maybe straight runs on racks working off the ground in an open area.

 

[shortcircuit2]

The stated reason for no NM is that rodents chew on the jacket and wires and that causes fires.

That is the good reason I was thinking of...