I recently acquired a lot of older BX/armored cable. Many have a little aluminum wire inside which I see wrapped around the ends of the cable on some of them where they were taken out of service.Some of the cables have white, green and black wires in addition to this aluminum wire, many are just white, black and the little wire. What is the purpose of this little aluminum wire ? Is this a primitive ground or bonding wire?
Roanin
It is an internal bond wire and the function is to shunt out any inductive component introduced by the spiral armor. It is doing it's job on every wrap. There is no need to terminate it but guys do have creative ways to do it anyway.
Yes. The idea is to fold and twist that drain wire back along the spiral in the armor. The screw in the box connector then contacts that drain wire to make a solid ground. It's not as good as a conductor-sized ground but it works.
It's not a ground. Read gfretwell's post
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