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Old 07-18-2008, 07:00 PM   #1
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metal shield as ground


With no municiple codes beyond the national, are you allowed to use the metal cable of Bx as a ground anymore? Whole house will be BX, 3/4 EMT,Greenfield and metal boxes. Is my 12/2 rendered useless? Does everything need a dedicated ground now? Thanks in advance!

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Old 07-18-2008, 07:07 PM   #2
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metal shield as ground


Your question is WAY too broad.

AC cable is fine; the sheath IS the ground.
Old "BX" cable (without the thin bonding strip) is NOT acceptable as a ground.
"Greenfield" is OK to use as a ground for 6' or less.

If you are into it this far I suggest you check out NEC 250.118 Types of Equipment Grounding Conductors

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Old 07-18-2008, 07:36 PM   #3
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metal shield as ground


Thanks Speedy, so AC is BX with the thin strip that gets wrapped back around the sheathing. The Bx I was planning on using is relatively new ( the raised part of the sheathing is colored black, and it does have the thin strip). I do have a roll of 12/2 with ground, but was planning on using that for kitchen and bath GFCI circuits, and air conditioning dedicated lines, while using the black Bx for the outlet circuits. Untill I got a phone call from a friend who knew what I was planning, telling me they don't accept the metal sheathing as a ground anymore. The project is in Wayne Co PA
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Old 07-18-2008, 08:05 PM   #4
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metal shield as ground


there are two types of cable that are fairly similar but distinctly different.

AC- the modern version of BX. It has a bare aluminum wire laying inside the metal sheath, in full contact with the sheath. Conductors have a paper wrap.

MC- uses the same sheath, they both look like small metal flex. There is no bare aluminum wire (I know the new MCaP or whatever but speaking of typical), conductors are wrapped with a poly covering.


ac cable- the sheath IS acceptable as a EGC due to the aluminum wire. Make sure you use cnnectors listed for use with AC cable and you must use the little red throats or insulators.

MC- the sheath is not rated as an EGC but there will be an insulated EGC in the group inside (generally is with AC too but can be made without). Do not need to use the red throats. Connector must be listed for use with MC

those rules are per the NEC. Local rules can be anything but you said there are none so the above info would reflect your situation.

you can get sheathing in all sorts of color markings black usually indicates single circuit. Black and red- two circuit.
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Old 07-19-2008, 03:45 AM   #5
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metal shield as ground


Thanks nap, I'ts not the mc . I always pop in a red bushing before wrapping the strip around the sheathing.
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