ceiling light with lathe and plaster

I have a 1924 house with knob & tube wiring in some places. I am having trouble following the single knob & tube wire in my attic after it leaves the ceiling light. It seems to disappear into the attic floor boards 2 feet before it reaches the edge where the top of the wall of the room would be. How do I find this wire? Is there anyway to replace it with romex? Even if I tear out the bedroom wall and rewire from the light switch up to the attic , how do I get the romex into the attic if it has to go through a very thick joist? Must I destroy the ceiling as well? I guess they used to run the knob & tube directly in the plaster? thanks.
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They were relatively paranoid about electricity during K&T days, and I _highly_ doubt that it's buried in the plaster.
If the wiring is in good shape (most K&T still is), I wouldn't just replace it for the sake of replacing it. Most inspectors I've spoken to tell you not to bother unless you're doing major rewiring and have to take the plaster off anyway.
If the section is in tubes, you can sometimes pull it, but the remaining holes (especially if the tubes don't come out) will probably not be big enough for romex.
There are some electrical wiring detectors on the market, much like the electronic stud finders. Not _too_ pricy. But not entirely cheap either.
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Chris Lewis, Una confibula non set est
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snipped-for-privacy@yahoo.com (margaret flaherty) wrote in message

If there are knobs holding on to the wire in the wall you'll never pull new romex by attaching it to the existing wire and pulling it through. Just abandon the K&T in place and run new romex. You can measure to make sure you're over the switch and drill a new hole from the attic side. Drop the romex down and then run it to the ceiling fixture. The K&T wire from the switch to the fixture can just be left in place. You can also run power to the switch down through the wall in the same fashion or dril a hole from under the house and then use a fish line to get it to the switch. I just rewired my whole house this way. There is no need to rip out a lot of plaster.
Greg
Greg
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