On 3/3/2013 7:22 PM, Mikepier wrote:
I'm running new electric in a friends basement and so far uncovered a
lot of bad wiring jobs, buried splice boxes, you name it. So now I
noticed that the central A/C compressor is wired with 10 guage wire.
I'm pretty sure its suppose to be 8 guage. And also the existing 10
guage wire is hooked up to a 40 A breaker, which of course is not
right, its suppose to be a 30A breaker.
So since everything is wide open now, I was wondering should I run
new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton
unit, and the plate says "Min circuit ampacity 24.4 amps" and it also
says " Max fuse or ckt bkr 40A".
Even if the unit has been running fine all these years, I'm wondering
what happens down the road if it needs to be replaced with a new unit
that needs more amperage. the existing 10 guage wire will not be
sufficient I'm thinking.


In The U.S., standard gauge copper wire for a 20 amp circuit is 12 gauge
and 10 gauge for a 30 amp circuit. Below is a link to a chart
for standard current ratings for home wiring. There are all sorts
of different ratings for different insulation types, wire in free air,
in conduit or buried but the chart shows what any electrician would
go by if wiring a home. Aluminum wiring is usually one gauge size larger
for the same current carrying capacity as copper. ^_^

http://www.cerrowire.com/ampacity-charts

TDD