HVAC OCPD is oversized by 5 amps from the manufacturer's plate.

[zimm]

Help out a home inspector. Split HVAC heat pump- 240VAC OCPD was 30 amps and the manufacturer's plate on the exterior unit said max is 25 amps. I know that the branch wiring can be lighter gauge than required for a circuit on HVAC, but can the breaker be oversized? I think not, but then again google shows a bunch electrician chatter about 5 amps over is okay and home inspectors overreact. I just want to report was is right and wrong here.

I can't seem to find an actual copy of NEC 440 without buying a subscription either.

 

[d0nut]

Maximum means maximum. If the unit's nameplate said max 25 amps, there needs to be a 25A or smaller circuit breaker or fuse in the branch circuit.

 

[zimm]

Maximum means maximum. If the unit's nameplate said max 25 amps, there needs to be a 25A or smaller circuit breaker or fuse in the branch circuit.

Thanks for clarifying.

 

[infinity]

I agree with d0nut 5 amps is not okay. "Caveat emptor" when you get info from the Internet.

 

[solarken]

I can't seem to find an actual copy of NEC 440 without buying a subscription either.

 

[augie47]

Also read the nameplate carefully. Some minisplits we see call for "Fuse protection" as opposed to fuse or breaker. If the name plate only mentions fuse the protection must be by a fuse at the panel or disconnect.

 

[Crash117]

Also read the nameplate carefully. Some minisplits we see call for "Fuse protection" as opposed to fuse or breaker. If the name plate only mentions fuse the protection must be by a fuse at the panel or disconnect.

To continue with Augie’s thread, if it’s fuses only, just leave the 30 amp breaker as long as you’re on 10 gauge wire and use a fused disconnect with 25 amp fuses and you’re covered just right.

 

[mtnelect]

Also, read the Installation Instructions from the manufacturer ... It might require 60 degree wiring only, usually located as a "foot note".

 

[curt swartz]

Also, read the Installation Instructions from the manufacturer ... It might require 60 degree wiring only, usually located as a "foot note".

The footnote in the image you posted does not require 60C wiring. It is stating their recomended wire size is based on 60C wire 50' long.

Also don't put too much into manufactures spec sheets. They don't always match the actual units nameplate that should be used for circuit sizing.

 

[jaggedben]

I see oversized OCPDs on HVAC units *all the time*.

 

[ramsy]

can't seem to find an actual copy of NEC 440 without buying a subscription either.

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2020 NFPA-70 422.62(B)(1) nameplate data requirements, with max fuse or breaker, are subject to temperature limits per 110.14(C).

Meaning wire size is restricted by the lowest temperature tolerance.