In alt.home.repair on Sat, 5 Jul 2003 19:51:03 -0400 "Alexander
Galkin" <(E-Mail Removed)> posted:
>I am updating wiring in my basement as part of major renovation project. I
>have three basement recessed light circuits sitting on the same breaker.
>There is 12 AWG wire running from main panel to the entrance switch box and
>from the switch box there are three separate 12 AWG wires bringing power to
>each of three recessed lights circuit. One of the circuits are 4-way switch
>that controls 4 recessed lights. Unfortunately one of three switches has old
>AWG 14 wire running to the nearest box and there is no way to replace it as
>it is virtually inaccessible. Al other wires are new AWG 12. There are total
>of 25 recessed lights so maximum amperage may exceed (or be near) 15 A.
It's important to be concerned about the expected load, but one should
also think about the unexpected load. For example maybe there will be
a total short circuit. Even though 14 gauge wire is only rated for 15
amp, I'm sure it can carry more than 20 amps for a few seconds in case
of a total short, and the 20 amp circuit breaker will blow.
Besides the situation described by someone where a later person
increases the load, the theoretical problem now would be that there
was some partial short circuit, whatever that would be, that allowed
ore than 15 amps to flow, but fewer than 20. The breaker would not
trip, but the wire would in theory be hot enough to start a fire.
(well, not if it were 16 amps. It would just be a little hotter than
at 15. I don't know when it gets hot enough to make a fire. Although
I have phone lines in the house that sometimes work fine and sometimes
give a big hum and don't work. There's no telling what can happen.
If you can't change the wires, can you put a 15 amp circuit breaker in
that circuit only. Is there any way to do this without a circuit
breaker box? I don't know. What about a light bulb socket, or a
screw-in fuse socket, rated for more than 15 amps that has instead a
15 amp fuse. Presumably it will never blow, so one box of 4 will last
you forever. If it does blow more than once, you'll decide what to do
then. Is such a fuse within code. If there are no exposed metal
parts it certainly seems safe enough. If not there must be
minicircuit breaker boxes. Or bring the 14 guage wire back to the
main fuse box and do it there. (All wire nuts must be within a
junction box, I beleive. (What about soldered wires?)
> I
>want to use 20 A circuit breaker but I have concern over the switch AWG 14
>wire. Again, the switch is basically in sub-circuit that has only 4 lights
>that is considerable less even then 15 A. So may I safely use 20 A circuit
>breaker in main panel?
>
Meirman
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