really old BX

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electricalperson

electricalperson

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massachusetts
today i worked with some really old BX. looked like it had a super strong armor sheath and after i stripped it to put it in a new box, the conductors were wrapped in cloth that seemed to be dipped in wax. after i cut the cloth covering off each conductor was coated in the wax also. anyone ever see this or knows how old that could be? we also found a box of mecca cigarettes dating back to 1909
 
Yes, I've seen that stuff. And you're correct it's just really old BX. Surprisingly if you strip back the armor the conductors are usually in pretty good shape even if they're 80 years old.
 
We see that stuff here in Jersey fequently in these old plaster/lath homes. It is a little more work to get those conductors out of that waxed fabric jacket.

What is a real blast is to do this in a 100 degree attic, throw a little sweat on those waxed cables and it is as good as oiled! I have come close to slicing up my fingers while working this stuff!
 
The insulation is called varnished cambric. Cambric (cloth) is a term also used in furniture making. Varnished cambric insulation holds up well except in the electrical boxes above light fixtures where it gets very brittle. If you don't mark the wires as soon as you open a light fixture you may end up with 4-8 bare wires wondering which is which. In the same period they used round shallow pan boxes and wired the outlets vertically from the lights.

Dave
 
Tiger Electrical said:
The insulation is called varnished cambric. Cambric (cloth) is a term also used in furniture making. Varnished cambric insulation holds up well except in the electrical boxes above light fixtures where it gets very brittle. If you don't mark the wires as soon as you open a light fixture you may end up with 4-8 bare wires wondering which is which. In the same period they used round shallow pan boxes and wired the outlets vertically from the lights.

Dave
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I've seen all that, PLUS a live natural gas line...
 
Yes, it's really old armored cable and probably doesn't have the bare shunt wire inside the metal armored casing either.
 
goldstar said:
Yes, it's really old armored cable and probably doesn't have the bare shunt wire inside the metal armored casing either.
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I agree.

It's interesting to consider, that this was one manufacturer's solution to how to make the BX.

Just as today, there are subtle, and not so subtle, differences between different manufacturer's NM-B.
 
Yes, that old "BX" was and still is murder to work with. I have a lot of respect for the guys who worked back in that era, when I think of what they had to work with, the tools they worked with and the pay. Oh yea, and the lack of ease of which we can get info today. :wink:

Here are a coupler of pictures of some of the the "old stuff", as mentioned in Tiger's post.
IMG_2497.jpg




IMG_2474.jpg
 
Just looking at the pictures of that old BX makes me cringe.I wonder what the stuff we are putting in today will look like in a hundred years.:)
 
infinity said:
Yes, I've seen that stuff. And you're correct it's just really old BX. Surprisingly if you strip back the armor the conductors are usually in pretty good shape even if they're 80 years old.
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yea the conductors were in really good shape. i meggered the cable to make sure and it was an infinity reading on my megger
 
Don't forget the fires that were started with the old AC (BX) cable! The armor was grounded and a ground fault would heat up the armor since there was no internal bonding strip of copper or aluminum in intimate contact with the armor for its entire length.
icon9.gif


As a result of this fact, if you come across the old AC cable, replace as much of it as possible. :smile:
 
charlie said:
Don't forget the fires that were started with the old AC (BX) cable! The armor was grounded and a ground fault would heat up the armor since there was no internal bonding strip of copper or aluminum in intimate contact with the armor for its entire length.
icon9.gif


As a result of this fact, if you come across the old AC cable, replace as much of it as possible. :smile:
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It is funny you should mention this.
The pictures I showed are from a job I went to where the firemarshal is saying the old wiring in the house caused this fire
IMG_2463.jpg
 
Pierre C Belarge said:
The pictures I showed are from a job I went to where the fire-marshal is saying the old wiring in the house caused this fire
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I wondered why no one else brought up this subject? I suspect the fire-marshal is dead on correct (pun intended, I hope no one died in the fire?). :-?
 
iaov said:
Just looking at the pictures of that old BX makes me cringe.I wonder what the stuff we are putting in today will look like in a hundred years.:)
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I live in the Chicago area where we normally do residential in EMT with THHN wire. I helped my dad (retired electrician) pipe and wire his home in 1977 with THHN. I recently did some work at his home. When opening junction boxes I noticed the THHN looked like I just pulled it yesterday. It's my opinion that in 100 years from the installation date it will be just fine.
 
Joe T had some pictures of some old BX actually glowing red from ground fault current. They really got your attention when you saw them.
 
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