# Commerical renovations



## Fibes (Feb 18, 2010)

AC is the new day version of BX, MC is a different animal and they have different rules, see articles 320 and 330 for the specifics of each


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## Roycet5 (Sep 29, 2015)

So are there length restrictions on ac cable?


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## Roycet5 (Sep 29, 2015)

What's the difference? Between all three? Ac, mc, and bx. Ac and bx are the same, ok. Got it. Can ac be ran over 6 feet?


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## Fibes (Feb 18, 2010)

Roycet5 said:


> So are there length restrictions on ac cable?


Only as long as the roll you buy.


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## Fibes (Feb 18, 2010)

Roycet5 said:


> What's the difference? Between all three? Ac, mc, and bx. Ac and bx are the same, ok. Got it. Can ac be ran over 6 feet?


 
BX is only a slang term for AC so leave that out of your vocabulary.

The difference between the other two is explained here

http://www.afcweb.com/installation/mc-ac-cables-installation/


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## Roycet5 (Sep 29, 2015)

Ok. Thanks because I was talking with someone and they told me according to the code you can't run ac over 6 feet. But I've seen a lot of stuff ran over 6 feet. Thanks for your response. Great speaking with you


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## Roycet5 (Sep 29, 2015)

6 feet is the maximum for mc cable right? Or not?


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## bigdan1 (Jun 16, 2013)

6' from the last support to what ever equipment it feeds. Other than that you can run it as long as you like. You'll just have to support it every 4.5' and with in 12" of a box.


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## theJcK (Aug 7, 2013)

It also harkens back to the days of not having a egc I thought.. honestly havent read that in a LONG time..


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## Electek inc (Mar 11, 2016)

MC as a wiring method has no limitations on length.


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## wcord (Jan 23, 2011)

Roycet5 said:


> Ok. Thanks because I was talking with someone and they told me according to the code you can't run ac over 6 feet. But I've seen a lot of stuff ran over 6 feet. Thanks for your response. Great speaking with you


Most engineers specify a max 6 ft length for drops to fixtures.
Keeps the area above the T-bar nice and neat


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## Vintage Sounds (Oct 23, 2009)

Roycet5 said:


> Ok. Thanks because I was talking with someone and they told me according to the code you can't run ac over 6 feet.


Sounds like whoever told you that doesn't actually read the code. Six feet maximum is usually a job spec in buildings where everything is supposed to be in conduit. I bet that guy is one of those people who thinks it's "code" to run #12 for everything in a commercial installation too.


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## millelec (Nov 20, 2010)

theJcK said:


> It also harkens back to the days of not having a egc I thought.. honestly havent read that in a LONG time..


You're right, the 6' total limit was if it was being utilized as the ground.


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## bobbarker (Aug 6, 2015)

The only 6 foot rule for AC wire with 6 feet is in 320.30(D)(3) which has to do with unsupported cables 

I am wondering if the person who told you more than 6 feet of AC can't be used is confusing Flexible metal conduit with AC because flex does have a 6 foot rule in regards to its length for for utilization equipment ie when you pipe to a transformer and change over to flex that flex can not be longer than 6 feet


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## KGN742003 (Apr 23, 2012)

bobbarker said:


> The only 6 foot rule for AC wire with 6 feet is in 320.30(D)(3) which has to do with unsupported cables
> 
> I am wondering if the person who told you more than 6 feet of AC can't be used is confusing Flexible metal conduit with AC because flex does have a 6 foot rule in regards to its length for for utilization equipment ie when you pipe to a transformer and change over to flex that flex can not be longer than 6 feet


Got a code reference for that 6' to utilization equipment?


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## bobbarker (Aug 6, 2015)

Local thing by inspectors here


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## biltheref (Apr 10, 2013)

kgn742003 said:


> got a code reference for that 6' to utilization equipment?


348.20?


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## macmikeman (Jan 23, 2007)

You guys are mixing up mc and greenfield or also know as flexible metal conduit. Greenfield can be run without a ground under certain conditions for any distance and needs a ground wire for other conditions like vibration. NEC 348.60


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## bill39 (Sep 4, 2009)

macmikeman said:


> You guys are mixing up mc and greenfield or also know as flexible metal conduit. Greenfield can be run without a ground under certain conditions for any distance and needs a ground wire for other conditions like vibration. NEC 348.60


I agree with macmikeman about mixing up the definitions. Here in the midwest we always used the term "greenfield" for empty flexible metal conduit. We used the term "BX cable" for a roll of flexible metal conduit that had factory installed wires.

I also believe he is correct about the ground wire but not 100% sure. It's been awhile since I've run any.

There used to be a great website called Tradeslang.com that describe alot of this stuff but it went away.


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## Electek inc (Mar 11, 2016)

I think what we call bx is actually known as armored cable in the code. Not to be confused with metal clad cable. A.C. has an aluminum or copper bonding strip and M.C. has a grounding conductor. Also, anti-shorts are required for A.C. Greenfield is the first company to make flexible metal conduit thus the name. Under certain conditions you do not need an e.g.c.


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## Signal1 (Feb 10, 2016)

Initially there were two experimental armored cable types invented by Harry Greenfield for the Sprague Electric company of New York. One was call experimental cable A or AX, and one was experimental cable B or BX. Well BX is the one chosen to go into production and when General Electric bought out Sprague, they marketed their Armored Cable under the trade name BX. That's why many people call it BX today.

Much like we call NM Romex, Which was first first produce by General Wire Company's Rome Wire Division in Rome NY.


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## donaldelectrician (Sep 30, 2010)

Signal1 said:


> Initially there were two experimental armored cable types invented by Harry Greenfield for the Sprague Electric company of New York. One was call experimental cable A or AX, and one was experimental cable B or BX. Well BX is the one chosen to go into production and when General Electric bought out Sprague, they marketed their Armored Cable under the trade name BX. That's why many people call it BX today.
> 
> Much like we call NM Romex, Which was first first produce by General Wire Company's Rome Wire Division in Rome NY.





Harry Greenfield invented " Greenfield "


That is one i did not know .




Don


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