old wiring through exterior brick wall

Old 09-16-04, 01:08 AM
Bearded One
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old wiring through exterior brick wall

My parent's house was built in the 40's with exterior brick walls. Interior side of outer wall some sort of cementitious material that chips away quite easily about two inches thick. The entire wall looks to be about a foot thick. My problem is that wiring for an exterior light that comes out of exterior brick is frayed and bare and needs to be repaired or replaced. Wiring comes out of box that looks to be set in mortar with no depth to the box. Just a 3/4" hole with two wires sticking out. I tried probing from inside wall looking for good wire but hit harder brick after going in two inches. I've never seen anything like this before.

Should I try to chisel out mortar and brick from outer wall around wire to expose enough good wire to repair? Will I be able to set in a new box in the old brick assuming I can get to "good wire" in the brick wall? Could this be an example of tube wiring in the brick? Is the wire buried behind the brick in an airspace where more digging through the masonry would expose it?

I'm stumped.
Old 09-16-04, 10:50 AM
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My house had something similar to what you describe. I had knob and tube wiring through my brick walls running to a front porch light. Removing the section that goes through brick wall is considerably difficult and not worth the effort. As with all knob and tube the best thing to do is to disconnect it on both ends of the circuit and leave it where it is. It's certainly not worth chiseling out brick and mortar. Drill a new hole. Depending on the specifics you may be able to chip out a bit of the mortar and snip off some of the old knob and tube and then repoint the joint to cover where the old wire exited the wall but don't try removing it all. Forget the old circuit even existed and wire a new proper one from scratch.
Old 09-16-04, 02:23 PM
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I would abandon the old wiring, too. You would have trouble making a connection inside the wall, anyway.

I will move this to electrical where they can tackle the finer points of this question.
Old 09-16-04, 03:47 PM
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If you can't pull the wires out then you don't have conduit. I doubt it's knob and tube.


Your best bet may be to rent a "rotary hammer" with a 7/8 or 1 inch bit and bore a hole to allow installation of a short section of conduit and finish as needed.

Others may contribute alternate proposals. Choose one and follow it faithfully.

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