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Home Repair - - If it ain't broken, don't fix it. Otherwise look here.
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Posted by Chas Hurst on August 22, 2005, 8:47 pm
> "I think it's reference to insulation or lack of. With no insulation
> the
> wire dissipates heat faster, hence the higher rating. "
>
> OK, I'm officially terrified now.
What? Afraid of a toaster in the attic.
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Posted by Matt on August 22, 2005, 6:00 pm
'What? Afraid of a toaster in the attic. '
ROFL.
For the OP:
Either don't insulate, or have your wiring upgraded. Also, try to find
a way to get access to the attic, other then via the roof.
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Posted by Jeff Wisnia on August 22, 2005, 8:37 pm
Chas Hurst wrote:
>
>>
>>>"It will support more power than today's cables of the same size."
>>>
>>>Huh?
>>
>>
>>I think what he means is that the wires that were used for, say 15 amp
>>circuits before are a larger gauge than those used now. You could run
>>20 amps over K&t circuits designed to run 15 amps - at least in terms of
>>the gauge of the wire.
>>
>>
>>Dimitri
>
>
> I think it's reference to insulation or lack of. With no insulation the
> wire dissipates heat faster, hence the higher rating.
>
>
IIRC knob and tube used insulated wire, but I can see some validity in
the its getting more convection cooling because it was free standing
between the insulators (knobs) whereas romex is usually stapled against
wood and often covered by insulation too.
Wouldn't bet on it without seeing the old specs myself though.
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Truth exists; only falsehood has to be invented."
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Posted by D. Gerasimatos on August 23, 2005, 6:52 am
>
>I think it's reference to insulation or lack of. With no insulation the
>wire dissipates heat faster, hence the higher rating.
Knob and tube is insulated. It's exactly what I said. The gauge of the
wire is thicker. K&t used 12 gauge wire for 15 amp circuits. Most 15 amp
circuits now use 14 gauge wire.
Dimitri
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Posted by Joseph Meehan on August 23, 2005, 12:34 pm
D. Gerasimatos wrote:
>>
>>I think it's reference to insulation or lack of. With no insulation
>>the wire dissipates heat faster, hence the higher rating.
>
>
> Knob and tube is insulated. It's exactly what I said. The gauge of the
> wire is thicker. K&t used 12 gauge wire for 15 amp circuits. Most 15
> amp circuits now use 14 gauge wire.
You are right that it is insulated. Of course by now a lot of it is not
all that insulated.
However you are at least a little off on the wire gauge thing. I am
not quite old enough to know if they originally required or used larger
gauge wire for a circuit. The stuff I have worked with did not. In fact it
used smaller gauge wire. The physical separation and the ability to
dissipate heat allowed it to carry the additional current per wire size.
>
>
> Dimitri
--
Joseph Meehan
Dia duit
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