MC vs. NM

[PCN]

We are looking at allowing some areas of our commercial single story buildings to be wired with NM instead of MC. I'm wondering what the cost savings would be.

Lets say for example you have 10 rooms (12'x12' 9' grid ceiling) with four receptacles in each and one switch each. Two 2x4 troffers in each room. Homeruns (20amp) are done with EMT anyway so they would not be included in this example. All metal framing on slab.

Is it worth it going to NM? Anybody care to through out a rough cost both ways?

 

[Rewire]

We are looking at allowing some areas of our commercial single story buildings to be wired with NM instead of MC. I'm wondering what the cost savings would be.

Lets say for example you have 10 rooms (12'x12' 9' grid ceiling) with four receptacles in each and one switch each. Two 2x4 troffers in each room. Homeruns (20amp) are done with EMT anyway so they would not be included in this example. All metal framing on slab.

Is it worth it going to NM? Anybody care to through out a rough cost both ways?

NM is not allowed above a drop ceiling in commercial bldg.

 

[PCN]

NM is not allowed above a drop ceiling in commercial bldg.

Well now I feel really foolish. Okay let's say drywall ceiling which is the case 50% of the time.

 

[cpal]

I see you are from New England
Which state are you considering NM in a non residential ceiling/??


It is allowed in in some cases in MA.

 

[gndrod]

NM commercial

NM commercial

I see you are from New England
Which state are you considering NM in a non residential ceiling/??


It is allowed in in some cases in MA.

Also include CA. WA, NV, to name left coast participants. Depends on local jurisdiction. Why would using NM home runs in conduit become an economical advantage? Just curious. rbj

 

[PCN]

I see you are from New England
Which state are you considering NM in a non residential ceiling/??


It is allowed in in some cases in MA.

ME,NH,VT,MA,NY. I thought Maine allowed it as well.

 

[PCN]

Also include CA. WA, NV, to name left coast participants. Depends on local jurisdiction. Why would using NM home runs in conduit become an economical advantage? Just curious. rbj

Most home runs pass through open ceiling areas or underslab. We always use conduit where it would be visible to public. It would be THHN in conduit not NM.

 

[Cavie]

Well now I feel really foolish. Okay let's say drywall ceiling which is the case 50% of the time.

Drop ceilings are not a problem. MC down to the first box and run around the side walls with the NM. MC up and over to another room and run around to walls again. Fast and cheep and meets code.

 

[PCN]

Ok, if nobody wants to divulge pricing I understand, I'm not trying to be nosey.

How about a percentage? Could one reduce cost 25% by wiring with NM?

 

[220/221]

Could one reduce cost 25% by wiring with NM?

I'd say yes. It is certaily 25% easier to work with. The cable price has GOT to be more than 25% less. A steel box will be more than 25% less than plastic.

 

[ibew441dc]

NM is not allowed above a drop ceiling in commercial bldg.

Agreed:smile:

Well now I feel really foolish. Okay let's say drywall ceiling which is the case 50% of the time.

Just because the ceiling has drywall does not mean its legal either. I would say that in most commercial environments with a drywall ceiling, the ceiling is typically suspended.

Although not exactly applicable in supporting an argument, 110.26(F)(1)(d) specifies that a dropped, suspended, or
similar ceiling that does not add strength to the building
structure shall not be considered a structural ceiling.

I am not a building code guy, and would be curious as to what it says??