NM Cable and three phase equipment

arnettda

Senior Member
Can I use 12/3 Nm to feed a 3 phase piece of equipment? I am bidding a job I guess you would call it commercial but it is a stick framed building with drywall as an interior finish. It is considered food processing but is just short of pharmaceutical. Besides general purpose receptacle and lighting outlets there are two 15 amp 3 phase pieces of equipment. Can I use NM to wire these. The wiring will not be exposed. I will poke out of wall into back of disconnect and then flex over to machine. I am sure I can use Nm in the type of construction I am dealing with is there any thing I am not thinking of? Can I mark my white wire blue and use it for three phase.
Thanks
 

iwire

Moderator
Staff member
Location
Massachusetts
Assuming NM is allowable in the first place then yes you may supply three phase loads with it.

I have wired many three phase, 480 volt exhaust fans with NM.
 

arnettda

Senior Member
Assuming NM is allowable in the first place then yes you may supply three phase loads with it.

I have wired many three phase, 480 volt exhaust fans with NM.
Is there any reason I should use MC cable instead of Nm in a installation like this?
 

arnettda

Senior Member
that depends, you only talked about the load end of the circuit. How does the NM cable make its way to the panel
I am hoping the panel will be recessed into the wall and can just run right into the top. If it end up being surface mounted I will have to set a gutter and run everything into the panel through a few nipples. Can I legally sleeve Nm through nipples that would come out of the top of the panel without a gutter. I would not think I could do that with MC cable.
 

jap

Senior Member
Assuming as stated that NM is allowed, then not really.

Unless it gives you or the owner a warm and fuzzy feeling.:)
Nothing about NM gives me a warm fuzzy feeling, especially if it and 480 are mentioned in the same sentence.

JAP>
 

jap

Senior Member
It will if you use the right box cutter.. very warm :)
I worked with a resi crew for all of about a half of a day that used box cutters to strip the sheath. They'd Pull the wire in the box and slice across the face of the NM up close to where it entered the box and pull the remainder free.

Not sure if they knew or cared but you could see the copper where they'd cut too deep.

480 would have never forgave them for that. :)

JAP>
 

Cavie

Senior Member
Location
SW Florida
I worked with a resi crew for all of about a half of a day that used box cutters to strip the sheath. They'd Pull the wire in the box and slice across the face of the NM up close to where it entered the box and pull the remainder free.

Not sure if they knew or cared but you could see the copper where they'd cut too deep.

480 would have never forgave them for that. :)

JAP>

I'm a 45-year rope slinger. Box cutter was all I ever used to strip the sheath. A good resi man can strip the wire with a pair of Klines. 3 phase does not have to be 480. Works down to 230 also. If you can use RX in this application would be up to the AHJ
 
I'm a 45-year rope slinger. Box cutter was all I ever used to strip the sheath. A good resi man can strip the wire with a pair of Klines. 3 phase does not have to be 480. Works down to 230 also. If you can use RX in this application would be up to the AHJ
I agree, that's how I strip Romex and I never knick it. Recently I trimmed out a job that was roughed by another, and he used those stupid romex sheath strippers and knicked almost every wire. I'm thinking, "learn how to use a utility knife dude...."
 

jap

Senior Member
I'm a 45-year rope slinger. Box cutter was all I ever used to strip the sheath. A good resi man can strip the wire with a pair of Klines. 3 phase does not have to be 480. Works down to 230 also. If you can use RX in this application would be up to the AHJ
That's how I strip it also when I install it but I strip it vertical, not horizontal.
I was only referring to 480v since that's what I-wire brought up.
It don't take much to strip NM.
I agree its up to the AHJ and your comfort level as to whether NM should be used in most cases.

JAP>
 

liquidtite

Senior Member
Location
Ny
In my personal opion I never like to run romex in a commercial application.
Just dosnt feel right
even if it is allowed .

I also hate to have mc exposed for homeruns entering flush mounted panel.

I'll try and have mcs enter back of gutter then nipple to panel .

Or if it's pre hung ceiling I'll pipe up to pull box .

but at end of day it's not my call it's up to the owner.
 

peter d

Senior Member
Location
New England
In my personal opion I never like to run romex in a commercial application.
Just dosnt feel right
even if it is allowed .

I also hate to have mc exposed for homeruns entering flush mounted panel.

I'll try and have mcs enter back of gutter then nipple to panel .

Or if it's pre hung ceiling I'll pipe up to pull box .

but at end of day it's not my call it's up to the owner.
You would really hate to come up here to New England. We have literally thousands of commercial buildings of every type, from supermarkets to high rise apartment buildings, wired entirely with NM cable. :thumbsup:
 

jap

Senior Member
In my personal opion I never like to run romex in a commercial application.
Just dosnt feel right
even if it is allowed .

I also hate to have mc exposed for homeruns entering flush mounted panel.

I'll try and have mcs enter back of gutter then nipple to panel .

Or if it's pre hung ceiling I'll pipe up to pull box .

but at end of day it's not my call it's up to the owner.
Pipe and wire guys like you and me are becoming a dying breed. Mostly due to the need to stay competetive.
I'll use MC where I can but it took me a long time to even get used to doing that.
I keep the NM for residential only and only projects and only with plastic boxes and fittings.
Even NM shorts out now if you tighten a metal romex connector on it too tight,,, not made like it used to be... oh well,, I'm just ramblin now.


JAP>
 

liquidtite

Senior Member
Location
Ny
You would really hate to come up here to New England. We have literally thousands of commercial buildings of every type, from supermarkets to high rise apartment buildings, wired entirely with NM cable. :thumbsup:

I lived in ct befor I moved to nj and started doing Elc wrk in nj .

but you guys don't have exposed romex entering panels that would drive me crazy .

dame I would deff be depressed slinging all that romex in a nice commercial space .


lol
 

Cow

Senior Member
Location
Eastern Oregon
I ran some 6-3 Romex for some 480v outdoor HVAC units once. It was definitely different, I had to verify the 600v rating before I pulled it, I'm so used to using it on 120 and 240v circuits only. I'm not sure why you wouldn't use it, if the situation allows for it??
 

iwire

Moderator
Staff member
Location
Massachusetts
but you guys don't have exposed romex entering panels that would drive me crazy .
Would not bother me a bit.

dame I would deff be depressed slinging all that romex in a nice commercial space .
I get more depressed not making money. :D

But NM in commercial has really ended here once the prohibitions against running it above dropped ceilings went into place.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
I worked with a resi crew for all of about a half of a day that used box cutters to strip the sheath. They'd Pull the wire in the box and slice across the face of the NM up close to where it entered the box and pull the remainder free.

Not sure if they knew or cared but you could see the copper where they'd cut too deep.

480 would have never forgave them for that. :)

JAP>
The bare conductors are still spaced away from each other and other conductive objects by the thickness of the insulation. Unless there is some type of contamination, 480 won't jump that gap.
 
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