- Location
- Massachusetts
I am out.
This is all well established, it is blowing my mind you are not seeing it.
Heat pump whip
- Thread starter crtemp
- Start date
- Status
I am out.
This is all well established, it is blowing my mind you are not seeing it.
- Location
- Connecticut
- Occupation
- Engineer
I am out.
This is all well established, it is blowing my mind you are not seeing it.
OK, I'll jump in.
240.4(G) specifically allows "small conductors" supplying air conditioning equipment to be protected per Art 440. Per Art. 440, the equipment in the OP requires a conductor with an ampacity of at least 22 and allows the conductors to be protected at not greater than 35A.
luckylerado
Senior Member
- Location
- Lake of the Ozarks
Agreed. Which table does 440 say to use? 440 allows you to upsize the OCP not downsize the required ampacity.
- Location
- Connecticut
- Occupation
- Engineer
And #12 THHN or THWN has an allowable ampacity of 25 at 75degC...which is greater than 22.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I hope the NM-B is not actually running outside, even in a raceway. Some AHJs may not even accept the transition from NM to whip being in an outside box.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I agree and that's the key, the ampacity of #12 THWN in the whip can be sized at 75° C which is 25 amps. The 20 amp limitation of 240.4(D) does not apply.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
440.6 directs you to the 'standard sizing tables' in article 310.
luckylerado
Senior Member
- Location
- Lake of the Ozarks
I think that I see my error. In my mind I am looking for something specific like:
"The provisions of 240.4(D) shall not apply"
but I see now that it is unnecessary and that the ** in 310.15(B)(16) do not modify the ampacity.
Maybe the equipment is marked 60°
"The provisions of 240.4(D) shall not apply"
but I see now that it is unnecessary and that the ** in 310.15(B)(16) do not modify the ampacity.
Maybe the equipment is marked 60°
- Status