Can you use knob and tube wiring with a 12v system?

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Old 12-08-11, 09:57 AM
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Can you use knob and tube wiring with a 12v system?

I have knob and tube wiring in an old house. I wonder if it is possible under the electrical code to replace the 120v service with 12v or even DC. It would make some things much easier, if it were legit.
 
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Old 12-08-11, 10:09 AM
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Watts is watts (volts X amps=watts) so to get the same watts as you would use at 120v you would need 10 times the amps and the wire size would have to be increased accordingly. From a practical point of view no.
 
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Old 12-08-11, 12:07 PM
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Ray brings up an important point. Also voltage drop is more of an issue with LV.

If you are trying to make a safer system it is more practical to rewire and add new circuits where needed.
 
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Old 12-11-11, 02:10 PM
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Well 20 to 30 watts of LEDs is fairly bright. So I would be talking about 3 amps with 12v. The idea is just to have a functioning light. Floor lamps would still be used. I am assuming it would not be allowed.

An alternative might be to try to use the existing wire to thread a larger diameter wires to the box in the ceiling. But I doubt it would fly with the inspectors.
 
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Old 12-11-11, 02:23 PM
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It would probably work but the low voltage Dc would have to be completely removed from the line voltage wiring and you need a DC source that would require line voltage.. Then too the insulation often crumbles off old wires just touching it so it may not be reusable.. I would say just leave in place till you can afford to replace it.
 

Last edited by ray2047; 12-11-11 at 08:04 PM.
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Old 12-11-11, 07:19 PM
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Speaking of insulation and knob and tube wiring you don't want to insulate around knob and tube wiring it can cause it to overheat and catch on fire. I thought I should mention this in case you were not aware of that. Personally I think knob and tube is a thing of the past and is dangerous especially if you put too much of a load on it. So be sure to replace it as soon as you can and until you do just don't put a large load on it.
 
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