Hey guys, I inspected an AC condenser where the manufacturer’s label stated a maximum 50-amp overcurrent protection. Inside the main panel, however, there was a 125-amp breaker labeled “Air Conditioner.”
The sellers responded by saying:
“The sellers would like the buyers to know that there is a sub-panel for the A/C unit in the attic crawl space that it seems the home inspector missed. The fused disconnect at the unit outside is 50 amp. The Certificate of Testing from WC Heating & Air Conditioning.”
A few things don’t add up for me:
I’ve never heard of an outdoor fused disconnect (with 50-amp fuses) being considered as the compliance point when the breaker in the main panel is oversized. My understanding is that the breaker feeding the circuit still needs to meet the equipment’s rating.
The attic sub-panel had no labeling and only contained a pair of 40-amp breakers and a 30-amp breaker—so no way of knowing what these were for. (BTW, how is a subpanel in the back of an attic with no walking boards permissable?)
The main breaker being 125 amps seems like a clear mismatch with the condenser’s label, regardless of fuses.
Has anyone come across a setup like this before? Specifically, is it ever acceptable for the oversized breaker in the main panel to be “satisfied” by fuses at the disconnect? Or would this be considered improper since the equipment label explicitly limits the maximum overcurrent protection?
The 125 amp OCPD has nothing to do with the AC unit because of the protection provided by the 50 amp fuses as per the unit nameplate. There may be other issues with the 125 amps OCPD feeding the sub-panel depending on the size of the conductors.
Are you sure that the 125 amp breaker is going to the outside service shut off? It makes more sense for the 125 to go to the attic subpanel, which then feeds the Air handler unit, heat strip, and whatever else that is not labeled. Is there only 1 A/C system at the house? or 2? I think some of the missing breaker labeling is throwing you off.
Even if it is what you say and that its 125 amps from the electrical panel to the service shut off, then 50 amp fuse to the outside unit, if the wiring for the 125 amp section meets ampacity requirements and the wiring from the service disconnect to the outside unit meets the MCA, what’s the actual problem?
Thanks for weighing in — that’s helpful. You may be right that the 125A is simply feeding the attic subpanel, and the lack of labeling there is definitely part of what made this confusing. I actually didn’t even see the sub in attic when I was there. There’s only one ac system at the property.
From my side, the main question I wanted to clarify was whether the 50A fuses at the disconnect are truly what satisfy the condenser’s nameplate requirement — and it sounds like that’s the case, provided the feeder conductors for the 125A breaker and the conductors from the disconnect to the unit are properly sized.
Yes the AC circuit is code compliant. If its fed from the sub-panel in you photo it’s actually being protected by the 40 amp circuit breaker in the sub-panel. That still would be code complaint even though the 40 amp breaker is less than the 50 amp MaxOCPD listed on the nameplate.
Was initially confusing because I never saw the attic subpanel during the inspection, and the 125A breaker in the main panel was labeled just “Air Conditioning,” not “AC subpanel.” That made it look like the condenser may have been on a 125A breaker, although it struck me as insanely oversized.
Do you guys typically pull the fuses at the disconnect? The seller did afterward and sent me that picture.
Are you guys free to accompany me on every inspection going forward to quickly help me sort out stuff like this. Lmk if it works with everyone’s schedule
Yes, if there is no breaker before the fuse that is sized correctly for the max breaker size/mca or the fuse is the only disconnect for the A/C condenser.
