Heat pump whip

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crtemp

Senior Member
Location
Wa state
I have a 10-2 nmb run to the outdoor heat pump. The unit has a MCA of 22.0 and a max breaker of 35 amps. It should be ok to run the conductors that are in the whip in 12 gauge correct? Do I have to keep the 10 gauge ground the same though since it is 10 gauge from the panel inside?
 

luckylerado

Senior Member
I have a 10-2 nmb run to the outdoor heat pump. The unit has a MCA of 22.0 and a max breaker of 35 amps. It should be ok to run the conductors that are in the whip in 12 gauge correct? Do I have to keep the 10 gauge ground the same though since it is 10 gauge from the panel inside?

I believe that 10s are required for the whip and the ground.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I do not think it does for conductors 10 AWG and under. That said, is there something in 440 to the contrary?

Why would it not apply for 10 and under... That seems to be clear in (D)

(D) Small Conductors. Unless specifically permitted in
240.4(E) or (G), the overcurrent protection shall not exceed
that required by (D)(1) through (D)(7) after any correction
factors for ambient temperature and number of conductors
have been applied.
 

crtemp

Senior Member
Location
Wa state
Well the inspector just showed up. He said it's fine. I forgot to ask him about the ground though. Does it need to stay a #10 since that is what is was from the start?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Well the inspector just showed up. He said it's fine. I forgot to ask him about the ground though. Does it need to stay a #10 since that is what is was from the start?

No you can drop down to 12 as the equipment grounding conductor never needs to be larger than the conductors of the circuit
 

luckylerado

Senior Member
Why would it not apply for 10 and under... That seems to be clear in (D)

Because 440 does not give ampacities. It points you to T310.15B16 thru 19 which points you back to 240.4(D) for **18 thru **10 awg.

**Refer to 240.4(D) for conductor overcurrent protection limitations. Again, I ask for a reference to the contrary.
 

luckylerado

Senior Member
Please explain
If in this case, #12 AWG wass acceptable, to your point, the EGC would indeed not be required to be larger than #12. T250.122 requires min #10 for this circuit being protected by a (assuming) 30 amp breaker. I could see a situation above 30 amps where you can reduce the phase conductors and not violate T250.122 but not below.
 

iwire

Moderator
Staff member
Location
Massachusetts
If in this case, #12 AWG wass acceptable, to your point, the EGC would indeed not be required to be larger than #12. T250.122 requires min #10 for this circuit being protected by a (assuming) 30 amp breaker. I could see a situation above 30 amps where you can reduce the phase conductors and not violate T250.122 but not below.

As you said, the EGC is never required to be larger than the circuit conductors, therefore 12 AWG circuit conductors protected by a 30 amp breaker only require a 12 AWG EGC.
 
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