Log in

View Full Version : New A/C Condenser - What wire gauge for supply?


Textures
Apr 9, 2008, 05:53 AM
Hi Experts-

I am setting a new condenser unit for central AC and need to know the gauge of wire to run to the disconnect box.

From the Manufacturer of the condenser:

13 SEER unit (higher efficiency)
Minimum Ampacity: 14.5
25 Amp Breaker
LRA 68


According to the need for the 25 amp breaker, NEC indicates that it must be #10 AWG wire, as 12 must not be run for any circuit over 20 amps.

However, the line length will be reasonably long- approximately 70 feet from the panel box to the disconnect at the unit. (Has to run clear across the house & garage.) I want to be sure that 10 AWG will be heavy enough to cope with the increased cable length.

Thanks in advance for any insights!

Stratmando
Apr 9, 2008, 12:05 PM
#10 would be great, and 30 Amp Breaker. Some may use 20 Amp, I would do 30.
Don't know where you live, Here we would use 3/4" PVC conduit. 2 #10's and a # 10 for ground, Then a pair of 12's for control wire that go between Air Handler and Compressor if needed this situation, I would verify the Number of control wires needed for system as some use 5 wires between units for control and diagnostics.