# When can you use romex, bx and mx in commercial buildings?



## HARRY304E

ElectricalNut said:


> I normally always just use mc but I always see romex. I know it's just someone coming in after hours and installing it but I think there is a place you can do it.
> I remember Something about it depending on how many people the building serves and how many floors?
> Also is there any case you can use bx now?


Romex.



> 334.12 Uses Not Permitted.
> (A) Types NM, NMC, and NMS. Types NM, NMC, and
> NMS cables shall not be permitted as follows:
> (1) In any dwelling or structure not specifically permitted
> in 334.10(1), (2), and (3)
> (2) Exposed in dropped or suspended ceilings in other
> than one- and two-family and multifamily dwellings
> (3) As service-entrance cable
> (4) In commercial garages having hazardous (classified)
> locations as defined in 511.3
> (5) In theaters and similar locations, except where permitted
> in 518.4(B)
> (6) In motion picture studios
> (7) In storage battery rooms
> (8) In hoistways or on elevators or escalators
> (9) Embedded in poured cement, concrete, or aggregate
> (10) In hazardous (classified) locations, except where specifically
> permitted by other articles in this Code.
> (B) Types NM and NMS. Types NM and NMS cables
> shall not be used under the following conditions or in the
> following locations:
> (1) Where exposed to corrosive fumes or vapors
> (2) Where embedded in masonry, concrete, adobe, fill, or
> plaster
> (3) In a shallow chase in masonry, concrete, or adobe and
> covered with plaster, adobe, or similar finish
> (4) In wet or damp locations


BX



> 320.12 Uses Not Permitted. Type AC cable shall not be
> used as follows:
> (1) Where subject to physical damage
> (2) In damp or wet locations
> (3) In air voids of masonry block or tile walls where such
> walls are exposed or subject to excessive moisture or
> dampness
> (4) Where exposed to corrosive conditions
> (5) Embedded in plaster finish on brick or other masonry
> in damp or wet locations


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## MDShunk

Never above the drop ceiling. Very often legal inside the walls, depending on construction type. In exposed ceilings, depends on the construction type permitted (not the type actually constructed).


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## ElectricalNut

I wired a apartment building/garage for my old company and the first floor all got wired in Romex and passed.

I meant when can I used bx As apposed to mc. Some jobs the engineer said to use bx for the outlets and use mc for the lights.
I just wondered If there was a reasoning behind this?


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## HARRY304E

ElectricalNut said:


> I wired a apartment building/garage for my old company and the first floor all got wired in Romex and passed.
> 
> I meant when can I used bx As apposed to mc. Some jobs the engineer said to use bx for the outlets and use mc for the lights.
> I just wondered If there was a reasoning behind this?


Florescent lights that are T-12 with the old magnetic ballast start better with the full sized ground where BX the sheath is the ground so if there were any lose connectors the ground would not be as good and the lamps may not start.


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## Skipp

HARRY304E said:


> Florescent lights that are T-12 with the old magnetic ballast start better with the full sized ground where BX the sheath is the ground so if there were any lose connectors the ground would not be as good and the lamps may not start.


 I thought BX had the bare ground wrapped in paper. 

In California you can never use romex for any commercial wiring. Resi concealed only.


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## Magnettica

First, there is no such thing as BX. It is called armored cable (AC) and that is how you will find it in the NEC. Yes, it is commonly called 'BX' because it was originally manufactured by the Bronx (BX) cable company. MC is generally lighter in weight and contains an insulated equipment grounding conductor whereas the AC uses the exterior armor as the EGC.


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## B4T

When did NM get banned above dropped ceilings.. I have seen plenty of strip malls that have it as the only wiring method used..


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## B W E

Skipp said:


> I thought BX had the bare ground wrapped in paper.
> 
> In California you can never use romex for any commercial wiring. Resi concealed only.


Not true. You can use it in commercial buildings up to the third floor. Some localities may prohibit it, but "California" allows it.


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## frenchelectrican

B W E said:


> Not true. You can use it in commercial buildings up to the third floor. Some localities may prohibit it, but "California" allows it.


Just don't quote moi wrong but I did recall someone mention to me that they did lift the restriction above third floor for NM cable ?

Merci,
Marc


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## BBQ

This is a question that is pretty much imposable to answer on a National level. There are so many local amendments and changes to the NEC about NM and areas on different code cycles you really need to check with the local code officials.

As far as the NEC, the 3 floor restriction was pretty much swapped for the 'not above suspended ceilings' restriction.


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## nrp3

Was there a MA amendment for that? I have to get another set of them.


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## ElectricalNut

I'm from jersey. I know mc has the ground and is lighter just wondered if there was any reason I would have to use it. Bx or AC (ive only ever heard it called bx around me) is definitely quicker because you don't have to deal with the extra wire but it isn't safer so I always use mc.

Like what b4t said, every job I get on I see romex above the dropped celling and some of the places were just built.


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## David40

*Subject to Physical Damage - Definition?*

Where do we find the definition for "Subject to physical damage"? That seems like such a subjective phrase it could mean just about anywhere.


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## Shockdoc

b4t said:


> when did nm get banned above dropped ceilings.. I have seen plenty of strip malls that have it as the only wiring method used..


1999


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## BBQ

David40 said:


> Where do we find the definition for "Subject to physical damage"? That seems like such a subjective phrase it could mean just about anywhere.


There is none and it is just as subjective as you say.


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## Southeast Power

ElectricalNut said:


> I'm from jersey. I know mc has the ground and is lighter just wondered if there was any reason I would have to use it. Bx or AC (ive only ever heard it called bx around me) is definitely quicker because you don't have to deal with the extra wire but it isn't safer so I always use mc.
> 
> Like what b4t said, every job I get on I see romex above the dropped celling and some of the places were just built.


AC can be used the same way as EMT it's just the jacket is the ground. We dont see much of it here in south Florida.
I dont like it just because its heavy and I just prefer MC. I like to find the rare roll of stranded MC. I buy as much as I can when I can get it.


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## David40

Thanks, that's about what I figured.

b4t, I learned that one the hard way. I wired a store in a strip mall and had to completely do the job over because of that change. Really pissed me off after using a wiring method for decades that never caused a problem and then all of a sudden it's not good enough. Anyway, I remember it had to do with the type classification of the building construction. So theoretically you can still use it in commercial buildings of the type in which it is approved to be used in. Again, totally subjective based upon location.


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## knowshorts

ElectricalNut said:


> I'm from jersey. I know mc has the ground and is lighter just wondered if there was any reason I would have to use it. Bx or AC (ive only ever heard it called bx around me) is definitely quicker because you don't have to deal with the extra wire *but it isn't safer so I always use mc.*
> 
> Like what b4t said, every job I get on I see romex above the dropped celling and some of the places were just built.


How is AC less safer than MC?

You can still get AC around here, but it does cost a lot more than MC. Supply and demand.


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## BBQ

knowshorts said:


> How is AC less safer than MC?


Some feel the lack of copper wire grounding conductor reduces the safety.


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## Roger123

jrannis said:


> I like to find the rare roll of stranded MC. I buy as much as I can when I can get it.


Purchased some a week or so ago at Home Depot, here in NE Ohio.


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## irocin350

334.12 Uses Not Permitted.
(2) Exposed in dropped or suspended ceilings in other
than one- and two-family and multifamily dwellings

haha I have seen more rx done this way !!!!


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## BBQ

irocin350 said:


> 334.12 Uses Not Permitted.
> (2) Exposed in dropped or suspended ceilings in other
> than one- and two-family and multifamily dwellings
> 
> haha I have seen more rx done this way !!!!


It was perfectly legal until the 2002 NEC was adopted.


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## knowshorts

BBQ said:


> Some feel the lack of copper wire grounding conductor reduces the safety.


So with that logic, MC is safer than EMT.


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## denny3992

jrannis said:


> AC can be used the same way as EMT it's just the jacket is the ground. We dont see much of it here in south Florida.
> I dont like it just because its heavy and I just prefer MC. I like to find the rare roll of stranded MC. I buy as much as I can when I can get it.


I have never seen stranded mc? U mean like 12/2?


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## hotwire1955

David40 said:


> Thanks, that's about what I figured.
> 
> b4t, I learned that one the hard way. I wired a store in a strip mall and had to completely do the job over because of that change. Really pissed me off after using a wiring method for decades that never caused a problem and then all of a sudden it's not good enough. Anyway, I remember it had to do with the type classification of the building construction. So theoretically you can still use it in commercial buildings of the type in which it is approved to be used in. Again, totally subjective based upon location.


 Keep up with code changes so you don't have to learn the hard way.


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## David40

Hard to keep up with anything that's arbitrary, subjective, and politically motivated. I've seen juridictions with more than one inspector who can't even agree on anything. It's a crap shoot at best, and in 50 plus years of experience, I find it totally useless, a joke.


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## kennydmeek

When I first started in the '80s we used it in single story office buildings where I live all the time. Then I spent the next decade and a half in an environment where there was no romex. I got a big surprise when I tried to use it an a building back here in my home county that was already all romex. Inspector looked at me like I had two heads...


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## cdslotz

> you really need to check with the local code officials.


and those pesky things called specs...


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## electricalwiz

ElectricalNut said:


> I'm from jersey. I know mc has the ground and is lighter just wondered if there was any reason I would have to use it. Bx or AC (ive only ever heard it called bx around me) is definitely quicker because you don't have to deal with the extra wire but it isn't safer so I always use mc.
> 
> Like what b4t said, every job I get on I see romex above the dropped celling and some of the places were just built.


NJ has ammended the NEC to allow romex above the drop ceiling, if you dont want to mess with the ground in MC you should use MCAP


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