PietroAZ
Member
- Location
- Santa Cruz Valley AZ
- Occupation
- Retired
Goal: To limit roof penetrations for installation of 3 Mini Splits
Each condenser would be fed by a 2p breaker at 20 amps (via 12/2 MC cable)
Also require an 120v 20 amp GFCI on roof, fed by a 1p breaker at 20 amps (via 12/2 MC cable)
All below roof and within structure (panel MC ...) before daylighting to condensers
Condensers have MCA of 14
Would like to take all through the roof with 3/4 or 1 inch IMC.
Could combine all with a 4457-DC (below).
Conductors dont appear to overfill the 3/4.
We are at 110F here for Design Ambient High Temperature.
I see THHN 12AWG at 30a and 0.87 as the derating multiplier for 106-113F.
And apparently an adjustment is also required 80% with up to 6 and 70% up to 9 conductors.
Math
30*0.87*0.8 = 20.88
With that the 120 GFCI would need to daylight on its own.
Did I get that even close to correct?
Each condenser would be fed by a 2p breaker at 20 amps (via 12/2 MC cable)
Also require an 120v 20 amp GFCI on roof, fed by a 1p breaker at 20 amps (via 12/2 MC cable)
All below roof and within structure (panel MC ...) before daylighting to condensers
Condensers have MCA of 14
Would like to take all through the roof with 3/4 or 1 inch IMC.
Could combine all with a 4457-DC (below).
Conductors dont appear to overfill the 3/4.
We are at 110F here for Design Ambient High Temperature.
I see THHN 12AWG at 30a and 0.87 as the derating multiplier for 106-113F.
And apparently an adjustment is also required 80% with up to 6 and 70% up to 9 conductors.
Math
30*0.87*0.8 = 20.88
With that the 120 GFCI would need to daylight on its own.
Did I get that even close to correct?