What to do with old knob & tube wires?


Old 08-21-07, 02:25 PM
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Join Date: Jul 2005
Location: Belmont, CA
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What to do with old knob & tube wires?

I'm planning to replace the knob & tube wiring in my house, starting with the receptacles. The house has ample crawl space so it will be easy enough to run new NM cable to the receptacles, but I'm wondering what I should do with the old knob & tube wiring that will be in the boxes.

After the receptacles have been rewired, what is the "correct" way to abandon the old wiring, according to NEC? It's not possible to get access to completely remove the wire. I've seen some conflicting recommendations, either to leave it in the wall, but not in the box, or terminate it in the box with a wire nut.

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Old 08-21-07, 02:30 PM
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Location: Near Lansing, Michigan
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Once it's de-energized, you may cut the wires off and abandon them inside the wall. I would not leave the dead K&T capped off in the boxes as it can never be legally re-used.
Old 08-21-07, 03:02 PM
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When installing new NM I would remove the receptacle boxes to make it easy to fish new cable. At that point it would be easy to cut the K&T wire. Then use old work boxes to replace the original boxes. Note if walls are wood I'd install metal gang boxes. Easier then enlarging holes to fit old work boxes. The boxes can be fastened by putting one leg of an NM staple through the brackets on top and bottom though I was taught #4 or #6 panhead screws.
Old 08-21-07, 04:35 PM
Join Date: Mar 2005
Posts: 433
I chew it out like a mole rat.

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