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#84361 - 03/24/03 08:54 PM Armored Cable: Type AC
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
I have a length of 8AWG Type AC cable that at one time ran from the panel to an electric cooktop (since replaced by a natural gas cooktop...)

I guess the cable is considered "8-3" as it has one each of a white, red and black conductor. There is no green conductor. This is not the old "BX" cable with cloth conductors--this is more modern.

NEC 250.4(A)(5) and 250.4(B)(4):
 Quote:
...The earth shall not be used as the sole equipment grounding conductor or effective fault current path.


Does this mean that the cable can not be used for any new work? While I have no use for it right now, I would hate to toss it if it can possibly be used for something later on.

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#84362 - 03/24/03 10:00 PM Re: Armored Cable: Type AC
stamcon Offline
Member

Registered: 03/24/01
Posts: 322
Loc: So San Francisco CA
ThinkGood, if the cable is AC, shouldn't there be a bonding strip inside, that is in contact with the armor? Have you stripped back the armor to see if it is there?

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#84363 - 03/25/03 08:54 PM Re: Armored Cable: Type AC
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
The bonding strip is there.

I'd like to re-phrase the question some...I know that Type MC has an insulated green conductor for grounding. Does Type AC need a separate conductor for grounding to be compliant with the NEC (1999 and/or 2002), or is the metal armor sufficient?

I thought that the bonding strip is not to be used as a ground. If so, what does it do

Am I about to get into the "grounding" vs. "ground" vs. "bonding" area?

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#84364 - 03/25/03 09:02 PM Re: Armored Cable: Type AC
CTwireman Offline
Member

Registered: 02/07/02
Posts: 839
Loc: Connecticut, USA
TG, the bonding strip inside type AC cable is there to reduce the reactance (resistance to alternating current) of the cable jacket. Without it, and under fault conditions, the jacket becomes a huge inductor which chokes the fault current, possibly preventing the OCPD from activating. Clear as mud?

Peter
_________________________
Peter

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#84365 - 03/26/03 04:33 AM Re: Armored Cable: Type AC
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Sure...an inductor...a duct that takes in the electrons, right?

Thanks for the explanation.

Still curious, do current (pardon the pun) regs require a separate EGC?

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#84366 - 03/26/03 04:39 AM Re: Armored Cable: Type AC
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
The armor of AC Cable,(0NLY IN CONJUNCTION WITH THE INTERNAL BONDING STRIP), provides an adequate, low impedance, equipment grounding path.
This is not the case with MC cables of the interlocked (spiral wound) armor type. In that case, as CT said, the configuration of the armor will choke the fault current. Therefore, with common MC, the insulated grounding conductor is required to adequately serve as the EGC.



[This message has been edited by Redsy (edited 03-26-2003).]

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#84367 - 03/26/03 07:08 AM Re: Armored Cable: Type AC
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Thanks again for the clarification!

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