I have 2 old circuits in my home that consist of the old nickel plated copper in BX cable with no ground. My question is ...I have heard (from an electrician) that this older BX has a very long "PATH" to reach the overcurrent protection device should the hot wire become exposed and make contact with the armored cable. I was told that the current would flow thru the BX much like a coil in a toaster (causing extreme heat on the cable) and possibly not trip the breaker to wit ...a fire hazard!

I have backed up the two circuits with AFCI's but am now thinking that I should also run them thru GFCI recepticles to add a ground fault feature to these 2 circuits.

Is it true that this older BX ground fault would not reach the breaker and trip it in a reasonable time and would the GFCI installation solve the problem??

It would be costly but I would pull out the old BX if necessary?? Please only Master electricians respond. I have "taken out" the recepticles on these circuits by adding new circuits to reduce load on these older circuits. They only feed luminaires in the bedrooms and halls. Thx in advance

Chafor

tkrussell

AC cable, aka BX cable, is still allowed to be installed, as per National Electric Code 2002 edition Article 320, and the metal sheathing is considered an equipment grounding conductor as per NEC 2002 Section250.118(9).

The issue with BX cable is that the continuity of the metal sheathing relies on the clamped connections at each box. Nowadays, with Romex having a separate ground wire, along with MC cable, which looks like BX, but has an insulated green ground wire, the worry of a loose clamp has disappeared.

Removing the BX is not necessary, just open each box on the circuit and tighten each clamp or connector. Thou BX may have a bit higher impedence, should, and still does work fine.

The person you spoke with obviously has his own experience, which I do not doubt, again simply because of loose clamps.

Protecting the circuit with AFCI is a good preventive measure, however, will not solve any loose clamp/connector that may exist. And just adding a GFI does not create a ground path that you think is missing, no problem using one on the circuit, it just does not offer what you think.

Havin the BX only for lighting circuits eliminates the possibilty of someone coming in contact with any BX circuit. Again, I do not mean to imply that there is any problem with BX cable, just trying to give you a comfort level.

By the way, I am a licensed master electrician in two New England states, one of the toughest locations in the country, outside of Manhattan, and a state certified inspector in one of them, with over 30 years experience from subdivision homes, custom high end homes , retail stores the size of malls, industrial up tp 13KV, commericial high rise 50 stories, data centers for financial, etc.

Again, check each clamp connection at each box for tightness, and I am sure you will be fine. BX sheathing is a continuous piece of steel, and most have an internal bare continous wire that is intended to assist with the continuity of the cable to act as an equipment grounding conductor.

chafor

Thanks for your reply.

I know all of the clamps are tight. No problem there. There is no bare grounding continuity wire in these very old BX cables. I have a better undrestanding now of the brief conversation I had with the electrician I spoke with. He did not mention that the problem lied with loose connector clamps. It makes sense.

I also appreciate knowing that I need not run the circuits thru a GFCI. I have enough work to do as it is!!

Thx for your time.
Chafor