A/C tripping the breaker

[Rthomas61]

Tough question here...

Our 3 year old Coleman Mach air conditioner started tripping the breaker this week. It started Saturday. Breaker tripped. Reset, started and tripped again. This went on about 4 times. Shut it off, let everything "settle," cleaned the rooftop unit (some bugs and stuff in it, not overly bad) and reset. Ran for a day and a half. Wifey came back and breaker had again tripped.

We are on a seasonal site, it's been in the upper 80's lately and everyone is running their A/C's. Mind you, it's not the first time it's been this hot.

What could be tripping the breaker? Possible "spike" in the line doing this? Something I'm missing? No other breakers are being tripped, just the A/C.

Anything I can try before calling in a technician?

Thanks in advance!

Bob

[Rthomas61]

Well, THAT was interesting!

Got down last week (post delayed a little bit) and everything was working fine. Let it run for 2 days and at 0300, the breaker tripped. I just happened to be awake so I checked. It wasn't the A/C breaker like wifey said, it was the MAIN!

That morning, I did some checking and thinking. On electric, I had the Fridge, A/C, Elec. hot water heater and an ice maker outside connected to the trailer. Perhaps a bit too much for the 30a trailer power. I decided to shut off the electric hot water and use gas. We don't use hot water that much.

Then I went and checked all connections and screws; they were all tight and fine. I cleaned the cooling fan under the power; it was a bit dusty and probably wasn't function to max ability.

Then I replaced the breaker. This Main blew several times before when I had electric heat going and some other stuff. Figured it may be weak from all the times it had been tripped. Problem is that the main was also part of the A/C breaker so I had to get a special 30/20 breaker. Not a Home Depot or electric supply breaker....as I found out the hard way. Quick trip through traffic to the RV supply and got the new breaker for $20

Installed and everything has been working for about 5 days now.

I'm guessing that all the appliances kicked on at one time tripping the breaker which would possibly explain the time between trips.

Thanks all for the help and suggestions!! Much appreciated!!!

[certified106]

Check the run and or start capacitor to make sure it is within it stated microfarad rating. Capacitors are my number one nuisance problem on home AC units when temps get hot outside.

[budwich]

Probably missed this somewhere, but perhaps you can "elaborate" on the problem some more... which might help narrow your search for a solution.
does your breaker kick off at AC startup or after a while running?

[time2roll]

Rthomas61 wrote:
It stinks because I never had an issue and am the only one having an issue right now. Then they changed the power cables and hookups and I'm having the problem. Wish they left it alone!

Very interesting. Yes check voltage and request new work if below 110 in the RV.

[Rthomas61]

It stinks because I never had an issue and am the only one having an issue right now. Then they changed the power cables and hookups and I'm having the problem. Wish they left it alone!

[myredracer]

Rthomas61 wrote:
What would cause the low voltage? That's the first thing I'm going to check. Check that at the breaker?

The problem lies with the NEC minimum code requirements for RV Parks and which edition of the NEC the CG/RV park was built to. The NEC requirements have improved over the decades but it is simply way behind all the high demand RVs nowadays (except for owners who built above the min. code requirements). You can't fault a CG owner for going cheap on the construction.

A single 30 amp pedestal has a 3600 watt demand but when there are multiple pedestals, the demand allowance drops significantly. Say a CG had a section of all 36 amp pedestals, the total demand is calculated at just 41 percent of 3600 watts (1476 watts) as per table 551.73. So if everyone is running an AC unit in warm weather plus other loads, the CG's system simply can't handle the total load and voltage goes down as a result. Not much you can do except to get an autoformer.

If you travel around to numerous CGs, it's almost guaranteed that if you go to an older one like in the 70s, there will be low voltage.

[justafordguy]

I agree with the others, check the voltage at the source and at your load. There are many other things you can check/fix but check the voltage first.

[SoundGuy]

Rthomas61 wrote:
What would cause the low voltage?

Load on the system - yours and everyone else's - excessive voltage drop from too long a cable run, excessive voltage drop from using cable inadequately sized for the task at hand. It ALL counts. 😉

Check it at the campsite post, both unloaded (i.e. before you plug in) and loaded (with everything running) AND at the camper when the circuit is under load. You can bet that if your unloaded source voltage is any less than 110 vac you can expect voltage under full load to be low enough to cause problems starting and running your A/C.

Here's a handy, easy to use Voltage Drop Calculator.

[Rthomas61]

What would cause the low voltage? That's the first thing I'm going to check. Check that at the breaker?

[93Cobra2771]

Check the voltage before you throw parts at it...

[fla-gypsy]

I suspect a low voltage situation in most cases like these.

[myredracer]

Before you start touching anything or calling a tech., get a voltmeter and check the voltage. With AC units the current goes up as the voltage goes down. In warm/hot weather and everyone running AC units, the voltage is gonna go down. How much is dependent on how the place was wired and how far you are from a transformer and/or main distribution panel. It's a common issue in the summertime.

AC units have a momentary inrush current of 5-6 times the normal running current so if the voltage goes down and the current up, a breaker may not be able to hold long enough to allow the AC unit to start. Changing a breaker can be a waste of time and money.

Check the blades on the shore power cord. If they are pitted or dirty looking, clean them until bright and shiny. If they dirty & pitted, there will be resistance and contribute to voltage drop.

If the cause is low voltage, you can get an autoformer (Hughes for ex.) to boost the voltage. A hard start capacitor can also help which reduces the startup current. You can try shutting off everything in your TT and seeing if the AC will start. This can sometimes work if you are marginal.

[time2roll]

It is the 20 amp branch circuit tripping right?

I would swap wires with another 20 amp breaker and see how that goes.
Is you water heat and fridge set to propane? Just more draw to lower voltage.

[ScottG]

First thing, check for a hot breaker. If it is indeed hot, check the connection at it. If that's OK then replace the breaker.
This goes for even if the breaker is hot for some external reason. Once they've been hot repeatedly, they get weak.