Our home inspection came in, and it’s pretty good overall. One issue that came up was this. The highest circuit breaker is 60 amps. The external AC unit, however, states that the highest circuit breaker should be 30 amps. Okay, we can do that, we thought. But then it turned out this made homeowner insurance companies nervous to the point of being unable to provide affordable insurance premiums. “We look for at least 100 amps!” one of them exclaimed.
What gives here? Any idea why the AC unit would have said the max breaker should be 30? Do you know why the insurance companies want at least 100?
Possibly relevant, but probably not, is that the inspection did reveal “a small amount” of active knob and tube wiring in the attic, which we’re having replaced (or more exactly, asking the seller to replace). But that shouldn’t be relevant to this particular question (even if it might have been relevant at all) since the issue seems to be what the external AC unit recommends, rather than anything inherent about the house’s wiring system.
This sounds like somebody is seriously confused. What do you mean by “highest circuit breaker?” Are you referring to the main breaker in the panel, which shuts off the whole house? Or simply the largest-capacity breaker in the panel?
The main breaker will be sized based on the service capacity of your hookup. A 100-amp service is common for modern construction, but an older house may have a 60-amp service. Upgrading the service, if necessary, is a full-day job for an electrician and will require cooperation of the local utility.
None of this is relevant your AC unit, which apparently wants a dedicated 30-amp circuit. Such a circuit will be on a two-pole, 30-amp breaker which should be connected to the AC and nothing else.
Unfortunately, I only mean “whatever that guy is talking about”, when that guy (the home inspector) says “The exterior cooling unit ID sticker specifies that the maximum circuit breaker should be no greater than 30 Amps. The breaker installed is 60 Amps.” That’s literally all I know, apologetically.
Okay, I will follow up with the inspector and clarify whether this is what he means.
OK, it sounds like they’re saying the maximum size breaker for the AC unit should be 30 amps. If there is in fact a 60-amp breaker there, that is potentially a dangerous violation, because it’s unlikely that the wires used to hook up the AC are sized for a 60-amp load. The fix should be as simple as swapping out the breaker and ensuring that the wires are the right size.
ETA: It sounds like the insurance people thought you were talking about the total electrical service capacity, not just the breaker for the AC unit.
Could be a problem somewhere if someone swapped out a 30amp for a 60 to keep it from tripping. Could suggest that the AC that is supposed to only need a 30 has a problem and is pulling too many amps. Just a thought.
But since this is part of a home inspection, I’d have the electrician that’s removing the knob and tube replace the circuit breaker as well and I’d say “Could you also make sure the wiring between the box and the AC are up to code as well”. There’s no reason to drop a 60 amp breaker in there, that’s a hack job so it wouldn’t hurt for someone to poke around and see if they can find out why it was done. An electrician might turn something up.
If it’s even kind of a warm day (over, what, 50 degrees), I’d have him turn on the AC for a little while and make sure it doesn’t blow the new breaker and if it does I’d see about having the homeowners replace or repair the condenser.
I mean, the best case scenario is that the breaker went bad and someone just dropped this one in there, but as someone else said, the condenser was popping it so someone putting a bigger one in. If you can’t turn it on until spring/summer, you might not find out until you own the house that it doesn’t work.
ETA, the other possibility is that it was, at one point, for powering a hot tub.
Home inspector said he couldn’t check the A/C because it’s too cold. I don’t quite understand that though–I mean, you can still turn it on and see if it works and blows cold air can’t you? What is it that I don’t know here?
ETA: My realtor said don’t worry about it because the home warranty will kick in if there turns out to be something wrong with it. But I’m not sure it’d be covered in this case, with the circuit breaker problems etc.
Don’t quote me on this, but I have read there is a small heater inside the compressor. This heater is always on (as long as power is going to the unit), even when the compressor is not running. The heater is used to keep the oil from freezing in the winter. This is why you should never remove power to the outdoor compressor unit, even in the winter.
IIRC, to carry 30 amps, you want 10 awg wire. For 60 amps, you want 6 awg. You can safely use a 30 amp circuit breaker on 6 awg wire. You CANNOT safely use a 60 amp circuit breaker with 10 awg wire. So that’s the first thing you’d want the electrician to check. If it’s wired with 10 awg, he’ll want to install a 30 amp breaker. If it blows when the AC is running, there’s a problem with the AC or the wiring from the box to the unit.
We bought our house in March and couldn’t test the AC until the high had been about 60 for three days. Our closing document required the sellers to have money in escrow to address any issues.
I don’t know if home AC units have that, but I can tell you that some commercial refridgeration/freezer compressors have them, especially the ones meant to be outdoors. In fact, our (commercial) freezer (with an outdoor compressor) went down in sub-freezing weather for a few days a while back and we had our HVAC guy come out to start it for us. The first thing he did was fire up only the block heater for a while to warm the oil.
Now, on the one hand a home compressor may have that in case a homeowner accidentally turns on their AC in the middle of winter. OTOH, it would probably be cheaper for the compressor manufacturer to put in a thermal switch that cuts power to the compressor when it’s below a certain ambient temperature. What they do, however, I don’t know and probably varies from unit (and model) to the next.
