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  1. #1
    Join Date
    Apr 2013
    Posts
    2

    Default Cloth wrapped BX cable replacement

    Hi, My son just purchased a house built in the mid 50's with Cloth wrapped BX cable. Under the cloth is something like rubber insulating the wires. It is very brittle and I want to replace it over time as we rewire or add circuits to home. Can we replace the 2 prong outlets with with 3 prong? (Is the BX housing ok as a ground for outlet grounding). Also since almost all wires are visible in basement with gentle loops from outlet to outlet, can we pull new wire through the existing BX?. My hope is to tie a nylon string to one of the wires and pull from the previous outlet box. mostly short runs, less that 8-10 feet. If that did not work, I was thinking of dropping one of the bx cables back through the floor , to create a straight cable to pull new wire, once i have new wire, pull in back into the outlet box. Am I being overly optimistic or is this possible. Figured I'd ask the experts before trying it. once I touch it, I'm committed to replacing it somehow, it's that brittle.

  2. #2
    Join Date
    Oct 2012
    Location
    Houston, TX
    Posts
    249

    Default Re: Cloth wrapped BX cable replacement

    If it is brittle you should replace it when you touch it. As for the grounding, you cannot use the armor plating as a ground for any new work, also remember if you take out a section of the old cable, you will ten be taking out the ground for that section.
    My guess is the electricians will recommend if you are replacing just an outlet you install a GFCI receptacle and use the "no equipment ground" label.

    You may want to invest in a residential code book as you are tackling a lot of work. They can be found for less than $20 at on.line and b&m retailers.

    Good luck, and post pics, before and afters are great(at least I think so).
    It's this old house, not this built after your dad was born house.

  3. #3
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    644

    Default Re: Cloth wrapped BX cable replacement

    Quote Originally Posted by NickL View Post
    Hi, My son just purchased a house built in the mid 50's with Cloth wrapped BX cable. Under the cloth is something like rubber insulating the wires. It is very brittle and I want to replace it over time as we rewire or add circuits to home. Can we replace the 2 prong outlets with with 3 prong? (Is the BX housing ok as a ground for outlet grounding). Also since almost all wires are visible in basement with gentle loops from outlet to outlet, can we pull new wire through the existing BX?. My hope is to tie a nylon string to one of the wires and pull from the previous outlet box. mostly short runs, less that 8-10 feet. If that did not work, I was thinking of dropping one of the bx cables back through the floor , to create a straight cable to pull new wire, once i have new wire, pull in back into the outlet box. Am I being overly optimistic or is this possible. Figured I'd ask the experts before trying it. once I touch it, I'm committed to replacing it somehow, it's that brittle.
    Nick, what you described is very dangerous. If you replaced the standard breaker which feeds the brittle BX wiring,with a GFCI or AFCI, chances are you would not be able to keep it from tripping.

    You're correct. Once you touch the wire it will probably short to the metal.
    For this reason, I would not attempt to replace any outlets, unless you have no other choice like breakers tripping or outlets falling apart.

    You may be lucky enough to do what you say, use the old cable to pull new cable in. If the BX was installed properly there will be a strap within 12" of any box and every 4 1/2 ft along the BX.

    Sometimes, in real old homes the walls don't have insulated walls so "fishing new wire (12-2 w/g Romex)is not all that hard.

    New Code requires Arc Fault Current Interrupters (AFCI) in just about every room that does not require a Ground Fault Current Interrupter (GFCI). And, 2014 Code will require it in even more places.

    One of my clients had the same situation you described with brittle BX and the only warning he received before a fire was his dog started barking at a receptacle. He did not even have a battery powered smoke detector.
    Good Luck from Columbiana, Alabama
    Maurice Turgeon, Hidden Content

  4. #4
    Join Date
    Apr 2013
    Posts
    2

    Default Re: Cloth wrapped BX cable replacement

    thanks for the quick replys, I will get a code book tomorrow, If I replace a section of BX with romex 14-2 with ground, and attach the ground wire to the metal box, wouldn't I be maintaining the same lvl of ground as originally installed? I will post pics as we go....
    Maurice, Sounds like I want to install AFCI breakers. There are only 2 that control 95% of the home. The other breakers are for dedicated circuits. Dryer, AC, stove ect, If I can not get them to stop tripping that would mean I have bare metal in in the boxes and the AFCI is doing its job. If they do not trip that means wiring is OK for now? (or AT LEAST UNTIL i TOUCH IT) Does that make sense to you. My main objective is to make sure my son is safe until we can get to it all. Can we sleep soundly if we install AFCI breakers.
    Thanks again for your help
    Nick

  5. #5
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    644

    Default Re: Cloth wrapped BX cable replacement

    Quote Originally Posted by NickL View Post
    thanks for the quick replys, I will get a code book tomorrow, If I replace a section of BX with romex 14-2 with ground, and attach the ground wire to the metal box, wouldn't I be maintaining the same lvl of ground as originally installed? I will post pics as we go....
    Maurice, Sounds like I want to install AFCI breakers. There are only 2 that control 95% of the home. The other breakers are for dedicated circuits. Dryer, AC, stove ect, If I can not get them to stop tripping that would mean I have bare metal in in the boxes and the AFCI is doing its job. If they do not trip that means wiring is OK for now? (or AT LEAST UNTIL i TOUCH IT) Does that make sense to you. My main objective is to make sure my son is safe until we can get to it all. Can we sleep soundly if we install AFCI breakers.
    Thanks again for your help
    Nick
    You're correct Nick but because 20A AFCI's are the same price as 15A AFCI's,I allways run #12. This means I can install more receptacles with the same number of AFCI's.

    If the AFCI does not trip with the BX, You do not have an immediate emergency. I would buy a few battery powered smoke detectors, if you don't have any now.
    Good Luck from Columbiana, Alabama
    Maurice Turgeon, Hidden Content

  6. #6
    Join Date
    Mar 2010
    Location
    Canada
    Posts
    86

    Default Re: Cloth wrapped BX cable replacement

    Quote Originally Posted by NickL View Post
    Hi, My son just purchased a house built in the mid 50's with Cloth wrapped BX cable. Under the cloth is something like rubber insulating the wires. It is very brittle and I want to replace it over time as we rewire or add circuits to home. Can we replace the 2 prong outlets with with 3 prong? (Is the BX housing ok as a ground for outlet grounding). Also since almost all wires are visible in basement with gentle loops from outlet to outlet, can we pull new wire through the existing BX?. My hope is to tie a nylon string to one of the wires and pull from the previous outlet box. mostly short runs, less that 8-10 feet. If that did not work, I was thinking of dropping one of the bx cables back through the floor , to create a straight cable to pull new wire, once i have new wire, pull in back into the outlet box. Am I being overly optimistic or is this possible. Figured I'd ask the experts before trying it. once I touch it, I'm committed to replacing it somehow, it's that brittle.
    Today's standards won't allow this. Type AC ( BX ) cable is required to have an internal bonding strip of copper or aluminum in intimate contact with the armor for its entire length.
    In other words, unless the AC/BX cable has the internal bonding strip you shouldn't attempt to use it for *grounding* , it's not safe or allowed.

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