Overheating/tripping electrical panel 110v AC breakers

[fixpro256]

Fulltime in a 2019 Keystone Montana High Country 331RL on 50 amp.

I have a monitor for amps and volts on each phase of my breaker panel. Voltage is 120-124 on both phases.

I have 2 rooftop HVAC units. Each pulls about 13amps. If I run one, the 20 amp breaker will get up to about 97 degrees. If I run both, eventually both breakers get up to over 105 and eventually trip due to heat, even with nothing else running that pulls many amps. I talked to the breaker manufacturer. They said the breakers are working correctly. Apparently the heat from one breaker is contributing to the heat of the other breaker.

Breakers are 20amp siemens. 12 AWG wire.
Voltage at both breakers is 124 with ACs off, 122 with both ACs on.

Keystone put the units on breakers that are on the same phase of the panel, right next to each other. I moved them. Now, the units are on different phases of the panel and they have a few breakers between them. That helped some.

This is a new rv. I'm in North Carolina and it's only in the low 90s here. My site is in the sun. This is the first time I have had to run both ACs for at least a few hours. I plan to spend time in places much hotter. But I don't see how I can if the ACs can't keep up with the demand without overheating breakers.

Before all this started happening, I had already fixed all the crappy keystone workmanship. I tightened the lugs where the wires connect to the plug on the side of the trailer, and all the breakers in the panel. I also tightened the lugs on the pedestal and reseated the breakers on the pedestal and in my breaker panel. And tightened all connections DC and AC in the breaker panel.

The panel is in a central area so the front of the panel is in the air conditioned space. The back of the panel is in a cavity that gets some slightly warm air from the cargo area, but not that much.

For now, I took the cover off, placed a small fan to blow on the panel to help dissipate heat better. The fan keeps them nice and cool, but I almost trip over it constantly.

How do other RVs run both HVAC units in 105-110 weather without tripping breakers?

Is this normal? Has anyone else checked the temp of their breakers with an infrared thermometer?

Any advice? Thanks

[CA_Traveler]

jolooote wrote:
Didn't know you could run an AC on only 20 amp breaker. Voltage at the AC unit always drops below 106 VAC. What is the AC volts at any outlet in the rig when the AC's are RUNNING? Years ago, I tried to run a single AC at a 20 amp only Ckt. campsite. Volts dropped to only 104. I ran it any ways. Two weeks later the AC compressor went out.

This is not uncommon. 30A rigs have larger wire with less voltage drop and 50A rigs have even larger wire with even less voltage drop as does their pedestal plugs.

And voltage doesn't drop to 106V with adequate wiring assuming the GC distribution system has good voltage and that includes a 20A pedestal.

[MEXICOWANDERER]

Kippered herring! These readings defy ohms law. The RUN usage is well within design specs. Confirm tightness of every screw and bolt from the rig entry, the ATS, invertor if present then into the power panel.

[enblethen]

OP has a 50 amp rig. Plugged into a fifty amp shore power connection. Each AC unit is on separate 20 amp circuit breakers.
OP: Verify what else is operating on 120/240 volts from shore power. Water heater?

[jolooote]

Didn't know you could run an AC on only 20 amp breaker. Voltage at the AC unit always drops below 106 VAC. What is the AC volts at any outlet in the rig when the AC's are RUNNING? Years ago, I tried to run a single AC at a 20 amp only Ckt. campsite. Volts dropped to only 104. I ran it any ways. Two weeks later the AC compressor went out.

[LittleBill]

according to the chart at the link below about 194F is the trip point.

if your sure the breakers are tripping at 105F, i would swap them out

Clicky

[fixpro256]

I updated the original post with a few more details.

Breakers are 20amp siemens. 12 AWG wire.
I tightened all the connections (AC and DC) in the panel.
Voltage at both breakers is 124 with ACs off, 122 with both ACs on.
Tried a new breaker, same brand, no difference

[Flute_Man]

Loose or poor connections will cause heat. Make sure all the breaker connections are clean and tight.
Jerry Parr

[enblethen]

Did you tighten the neutral connections in the very back of the 120/240 distribution panel?

[Big_Katuna]

Need more data. Voltage and amp measurements at the pedestal, RV panel and at or near the ac.

[time2roll]

Can you move them to get blank space or air gap to the next breaker for some cooling effect? As long as they are out I would replace with new and maybe a different brand.

[CA_Traveler]

What is the voltage at the A/C terminals when both are running? My CBs get much warmer than 105F. You have bad breakers, bad A/Cs, bad wiring/connections or low voltage or some combination. You might want to get a get a AC clampon ammeter and also measure the amps.

I run all 3 AC's in 120F weather plus whatever else I want w/o any issue on shore or gen.

Not sure why you're attempting to repair a 2019 unit but be careful that you don't void your warranty.

If you do decide to by a clampon then get one that measures both AC and DC amps.

[cavie]

midnightsadie wrote:
might check wire size going to these units.

50 year Master Electrician. I have no reason to check the temp of my breakers. If it does not trip don't worry about it. There is absolutely no reason for a panel to over heat unless it is over loaded or you have a low voltage condition. Be sure all connection are tight. Stop using the fan and fix the problem if there is one.

[midnightsadie]

might check wire size going to these units.