# Is there a minimum size Wire size for commercial?



## brother

bushwickbill said:


> I am doing a commercial reno and am in need of some help? My Boss told use to run 14/2, 14/3 BX Cable (Amoured Cable) on 15 amp circuits. Now the question is, I heard from a Diff J-Man that all wire in commercial has to be a minimum of 12/2 or 12/3 or greater? So is this refering to when you are running Loomex (NMD90)? Or does it also apply to BX too, Or neither? I have been looking in the code book and can't find a thing stating a minimum wire size for BX or Loomex when wiring a commercial job?
> I just would like some clarification on this. Don't need to do something twice:no:
> Thanx for any and all advice


 Unless theres a local amendment in your area, then the minimum is 14 copper or 12 aluminum. NEC 2008 310.5 table 310.5


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## drsparky

Not in the USA, I don't now about hoserland.


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## 480sparky

brother said:


> Unless theres a local amendment in your area, then the minimum is 14 copper or 12 aluminum. NEC 2008 310.5 table 310.5



Job specs will many times require a 12 copper minimum.


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## Wiredude

Like above, may or may not be allowed.
However, I know around here, there's not much of a price difference between #14 MC and #12 MC. Right now I'm seeing 14/2 MC all of $2/thousand cheaper than 12/2. I've seen times in the past where it was actually more.


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## bushwickbill

Good to know that BX can be 14/2. Anything on the loomex side of things. We are running a few drops in loomex. Does that also have a minimum of 14/2 or does that need to be 12/2?
thanks for the replies people:thumbsup:


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## Split Bolt

bushwickbill said:


> Good to know that BX can be 14/2. Anything on the loomex side of things. We are running a few drops in loomex. Does that also have a minimum of 14/2 or does that need to be 12/2?
> thanks for the replies people:thumbsup:


Keep in mind that you are in Canada and most of the responses you are getting are from the USA and are completely irrelevant to you!


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## gardiner

#14 either in BX or in conduit is legal in commercial if you’re using 15 amp breakers and there is no potential issues with voltage drop. Now the Loomex in a commercial building is another story and may depend on your local codes.


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## elecpatsfan

bushwickbill said:


> I am doing a commercial reno and am in need of some help? My Boss told use to run 14/2, 14/3 BX Cable (Amoured Cable) on 15 amp circuits. Now the question is, I heard from a Diff J-Man that all wire in commercial has to be a minimum of 12/2 or 12/3 or greater? So is this refering to when you are running Loomex (NMD90)? Or does it also apply to BX too, Or neither? I have been looking in the code book and can't find a thing stating a minimum wire size for BX or Loomex when wiring a commercial job?
> I just would like some clarification on this. Don't need to do something twice:no:
> Thanx for any and all advice


I asked my inspector this same question. He told me that 12 gauge copper is not enforced as a minimum size but is highly recommended due to the high demands of office equipment.


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## electures

brother said:


> Unless theres a local amendment in your area, then the minimum is 14 copper or 12 aluminum. NEC 2008 310.5 table 310.5


Is #12 AL still made?:001_huh:


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## BCSparkyGirl

bushwickbill said:


> I am doing a commercial reno and am in need of some help? My Boss told use to run 14/2, 14/3 BX Cable (Amoured Cable) on 15 amp circuits. Now the question is, I heard from a Diff J-Man that all wire in commercial has to be a minimum of 12/2 or 12/3 or greater? So is this refering to when you are running Loomex (NMD90)? Or does it also apply to BX too, Or neither? I have been looking in the code book and can't find a thing stating a minimum wire size for BX or Loomex when wiring a commercial job?
> I just would like some clarification on this. Don't need to do something twice:no:
> Thanx for any and all advice


no, I have run 14 in commercial.......while it is good practice to run 12, it is not required.........I have done commercial in Burnaby and in Surrey, but never have heard of a rule that specified 12 as a "must". It sure isn't in the code book. It all depends on what is called for in the specs. Some specifically ask for 12, but if they don't, then we run 14 on a 15A circuit.


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## bushwickbill

Thanx guys, I think that clears things up. Yes i do realize that in Canada our code is a little diff from your, But for the most part there is a lot of similarities.I went and asked him why the J-Man made that comment to me and he stated that in the specs it called for 12/2 min for loomex, And 1 inch emt for all data and fire alarm drops!


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## 480sparky

electures said:


> Is #12 AL still made?:001_huh:



Yes, but I don't think #14 AL is. If it is, there's no NEC table that would cover it.


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## acrwc10

When doing you load calcs for the receptacles you have to use 180va per outlet, on a 15 amp circuit that calculated at 80% that is only 8 receptacles per circuit. Art. 210.14(I)


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## Rudeboy

acrwc10 said:


> When doing you load calcs for the receptacles you have to use 180va per outlet, on a 15 amp circuit that calculated at 80% that is only 8 receptacles per circuit. Art. 210.14(I)


Mind quoting that one?
:blink:


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## acrwc10

Rudeboy said:


> Mind quoting that one?
> :blink:


 
Opp's 220.14(I) 

you have to use 180VA as your calcutated load per receptacle in commercial. Then you can only load the circuit to 80% of it's rating (15 amps in this case) 15amps times 120 volts =1800VA 
1800VA times 80% = 1440VA
Now you take the 1440VA divided by 180VA =8 receptacles per circuit rated at 15 amps (#14 cu) 

This is a commercial not a residential requirement.


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## HARRY304E

480sparky said:


> Yes, but I don't think #14 AL is. If it is, there's no NEC table that would cover it.


YAP!:laughing::laughing:


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## HARRY304E

Rudeboy said:


> Mind quoting that one?
> :blink:


i
Its in the code


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## Rudeboy

@Accrw,
Thanks for the proper code ref. and also an explanation.
thanks.
:thumbsup:


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## Rudeboy

HARRY304E said:


> i
> Its in the code


Orrly?
:laughing:


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## brian john

elecpatsfan said:


> I asked my inspector this same question. He told me that 12 gauge copper is not enforced as a minimum size but is highly recommended due to the high demands of office equipment.


 
Either he does not understand the basics of how wire sizing and OCPs work or he is just dumb.

There will be no more demand on a 14 AWG protected at 15 amps that a #12 AWG at 20 amps.

Where do these guys come from, you need to seriously have a FRIENDLY talk with this man


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## Carultch

Split Bolt said:


> Keep in mind that you are in Canada and most of the responses you are getting are from the USA and are completely irrelevant to you!


Not completely irrelevant. The laws of Physics work the same in both places.

The only difference is how the industry's authorities interpret these laws for practical safeguarding requirements.


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## daveEM

Wake up Car. The thread is 5 years old.


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## Carultch

daveEM said:


> Wake up Car. The thread is 5 years old.


I gotta stop posting on threads I find in the "related posts" section. I keep finding old ones from the past that the initiator doesn't care about anymore.

My favorite was the one about 20 ft conduit lengths that I found.


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## Electric_Light

Have a look at this: 
http://www.cooperindustries.com/con...e_Tech_Lib_Equipment_Grounding_Conductors.pdf

14AWG can only take 1690A. 12AWG can take 2680A for one entire cycle it takes for circuit breaker to interrupt. Available fault current can't get ahead of the one cycle rating of the conductor or you risk damage to the insulation. Things are inherently current limiting at 120v because of the impedance of the wires themselves by the time you get to the panel.

Larger service drop wires and larger transformer (relative to resi neighborhood one..) can easily put phase-to-phase or even phase-to-ground above 1700A depending on distance to transformer and permanently degrade the insulation. 

Shunt across six 9v batteries in series or across a 48v telecom battery bank with a 0.25A fuse. The fuse will pop either way, but it will be much more violent with the latter, because of the much higher let through.


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## Cincycaddy

Our specs call out for #12 minimum


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## 99cents

There is no generic term in the code book for "commercial".


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## don_resqcapt19

electures said:


> Is #12 AL still made?:001_huh:


 As far as I know there has not been any #10 or #12 aluminum on the market since the mid 70s.


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## NJWVUGrad

480sparky said:


> Job specs will many times require a 12 copper minimum.


Thank god someone reads the specs, we spend so much time writing them ....


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