ECN Forum Forums General Topics of the Trade General Discussion Area new breaker box blew out my a/c - who pays?

The A/C was manufactured in 2006. It has a diagnostic module which I also thought should have protected against overload. We have a Home Warranty and the A/C guy said he had to report to the Home Warranty Company about the oversized fuse. How can I prove to them that it's not due to the oversized fuse?

Thanks,
Uninformed

Maybe the installing electrician and the guy who upgraded the panel will help.

At a certain point someone is going to tell you the compressor was already going bad and the larger breaker was not the problem. It may have allowed it to sit there are run at the overload temperature a little longer than it might because of the compressor problem but the breaker is to protect the wire, not the compressor. The compressor would not have sat at locked rotor and operated the overload if there was nothing wrong with it.

My bet, a bad capacitor. I just had that with mine and the AC tech (neighbor) showed up with one in his pocket.

Somewhere close to the A/C unit should be a disconnect.

It is usually not part of the electrician's job, as a part of the panel change out, to check what size fuses are in it, or determine the proper size fuses.

The new breaker box has nothing to do with the A/C condenser failure.

Home warranties will look for any excuse not to pay. I think he has found one that in no way caused the problem, but it is an excuse to cause them not to pay.
The 50 amp breaker is in no way the cause of the compressor failure.

External fuses and circuit breakers,like those in a house's panelboard, have never been intended to generally prevent equipment from failing. Of course there will be some situations where the branch circuit device also acts as the motor protection, but then different sizing rules come into play.

If branch circuit protective devices, were intended to keep compressors from failing, we would not have verbiage in the code like NEC 2005 440.2 which allows for "greater than the marked rated-load current'.

The maximum protective device value from an equipment manufacturer may not have been sized to prevent a failure. The equipment often contains a compressor and a fan or two, so the branch device must inherently be larger than one chosen just for any of the individual components.

Regardless, if the manufacturer's instructions were not followed, pursue a warranty claim may be difficult.

I would not expect an electrician to investigate the correctness of protective device sizing, if the contract was 'replacement of existing'. However, I would expect the owner to be notified of common code compliance issues such as 110.3, 110.9, 110.14, and 240.4(D) which may become apparent during any replacement.

OK, I still wonder what the nameplate on the CU says, and is/was there a fused disconnect.

I see oversize fuses in discos with correct cbs in the panel; I see oversized cbs, and correct fuses in the disco, and I see non-fused discos with the proper cb in the panel.

All of the above are compliant, as long as it matches the mfg label.

Exactly. And very few installers understand this. One more I will add is the disconnect directly tapped from the load side of the main service with with properly sized fuses at the disco, and a code compliant tap in the service panel. I recently had a home inspector tell a HO this was so dangerous it should be de-energized immediately because the #8 THWN's could start a fire (in the conduit) from getting 125 amps pushed thru them.

Remember who you are talking about: Home Inspectors.