Split Phase Crossed on Two Air Conditioners

[chrisski]

I found both legs on my split phase for both my air conditioners were crossed. The diagram below shows what I mean:
So for the 16 years my house has been built, one 120 volt leg of the split phase leg from each air conditioner goes into Air Conditioning Circuit Breaker 1; the other leg of the split phase from each air conditioner leg goes into Air Conditioning Circuit Breaker 2.

I was testing circuits for my back up battery for my upcoming solar installation and I was puzzled when I tripped one circuit breaker, and both shut down. After a bit of trouble shooting I found the "wires were crossed." The four ton unit has a 40 amp circuit breaker and the five ton unit has a 50 amp circuit breaker, so you can see how I'm not happy about one leg of a 50 amp circuit going through a 40 amp breaker.

I will be getting someone out to fix this wiring. I hope it is as simple as changing where two wires terminate in a circuit breaker.

 

[chrisski]

Opened up the Circuit Breaker Box, and appears that won't be too hard for an electrician to swap wires around.

 

[aenyc]

Sounds like a fairly simple DYI

 

[chrisski]

Sounds like a fairly simple DYI

It does look like a simple fix. I'll get to this this weekend.

Tomorrow the solar installers will be at my house for the next 3 days putting up panels, wiring, inverter, and battery box. The installers are not supposed to install the seven backup circuits or mess with the breaker box until several weeks from that portion of the install. That several week delay is for the power company to inspect. Then they will be back to put the backup circuits.

I actually have a few weeks to Move these wires before this installation is complete and the system is live..

 

[timselectric]

That seems like an odd mistake to make. It almost seems like it was intentional. What size wire is running to the two units?

 

[chrisski]

That seems like an odd mistake to make. It almost seems like it was intentional. What size wire is running to the two units?

I do wonder if it was intentional to have both units go off if one breaker tripped. When I tripped each breaker individually both units shut down. Anyway, that will not work with having one of these units on the inverter backup.

I hadnot checked for wire size, and it does appear in the phot above the the left CB top wire is smaller and the right CB bottom wire is smaller. I would think the smaller wire is 40 amps and the larger wire is 50 amps. The actual picture on my phone has much better resolution.

@timselectric , What wire size would you think is on the 40 amp breaker and then on the 50 amp breaker? I would expect 6 AWG for the 50 amp leg and 8 AWG for the 40 amp leg. This gives me a good idea what wires to swap small wires to the small breaker and large wires to the large breaker.

I have found at least one other issue in the wiring in the house where the hot and neutral were reversed on a GFCI outlet that had several outlets behind it. I don't know if this caused a melted outlet connection, but whenthat circuit failed I opened that outlet and found that out.

 

[timselectric]

What wire size would you think is on the 40 amp breaker and then on the 50 amp breaker? I would expect 6 AWG for the 50 amp leg and 8 AWG for the 40 amp leg. This gives me a good idea what wires to swap small wires to the small breaker and large wires to the large breaker.

An A/C compressor is allowed a slightly oversized breaker to wire rating. Due to its large startup surge.
40a for #10 is fine. 50a should probably be #8.