Basic Question About AC Power Wiring

[HadEnough]

How are RVs usually wired up?

I have a standard arctic fox RV and I’m having trouble with the AC portion of the wiring.

Symptoms:

*After running an air conditioner for 4-5 hours, off an external generator connected to the shore power cable, I get a brownout” situation and the microwave turns on and off every second or two repeatedly during this brownout.

*Its getting worse. Sometimes I get the same thing on startup. Other times it randomly works great for hours and hours.

*when I use the onboard generator, it will either work great or it will have the same type of problem as the external. HOWEVER, when the external generator would have the brownout or cycling, the onboard generator is smarter and just shuts down.

*there seemed to be a VERY long delay tonight using the onboard generator before the power came on.


So far I’ve looked at the transfer switch. I opened it. Hard to see the contacts, but they didn’t really seem to do anything actually probably because I was on the shore power generator. And it was working fine.

So my question is related to diagnosis.

What components are involved?

What components are common to the shore power and the onboard generator such that they can cause brownouts, cycling on/off of power and the onboard generator to decide to shut down?

I’m looking hard at the automatic transfer switch but I don’t see any problem.

It seemed to get better a bit when I exercised the main breaker on the panel, but it’s intermittent and that may not even be it.

What components are there to check?

[enblethen]

Another place to check since you have genset, is the transfer switch. Proceed in same manner as distribution panel.
Happen on all power sources it sounds like in the rig.

[time2roll]

Run a 1500w space heater full and continuous and see if you have the same issue.
How old is the air conditioner? May need a clamp-on ammeter to check the draw and compare to specs.

[BFL13]

I thought a lock-up would pull a whole bunch of power and cause what you are seeing.

[HadEnough]

BFL13 wrote:
One thing might be compressor "lock up" which was what I was thinking of. I saw something there about making sure your air filter is clean. Whatever, it can get complicated.

IMO you do not have a wiring problem as such. It is the air conditioner.

No, the symptoms I described wouldn’t happen from a lockup.

There is an electrical problem. See first post.

It sure can get complicated it you have to isolate things and go through them. Which is why I’m trying to make sure I’m not missing any components in a typical RV AC system.

[BFL13]

One thing might be compressor "lock up" which was what I was thinking of. I saw something there about making sure your air filter is clean. Whatever, it can get complicated.

IMO you do not have a wiring problem as such. It is the air conditioner.

[HadEnough]

time2roll wrote:
Brownout as in low voltage? You will need to take some measurements with your voltmeter along the pathway.

Possibly just tighten all connections including at least the transfer switch and the breaker panel.

May want to start at the source when measuring voltage.

I’d love to. But you can never know when the problem will happen. It happens after like 5 hours of good power sometimes.

The air conditioner slows down. So I stop it immediately because I don’t want to damage it from bad power. I rush to check the power and it’s better already. Then it dies again. It’s completely intermittent.

Definitely starting by checking connections

[HadEnough]

Ok, sorry.

To be clear I’m 100% boon docking. I have 30 amp shore power AND the onboard built in Onan generator. Attached to the shore power cord is a Honda generator to run the air conditioning since I’m in Florida where you run it 8 hours a day. Didn’t want to put those hours on the onboard generator.

The behavior is the same for both generators, except the onboard generator is smart enough to shut off when things go weird.

Distribution panel and/or breakers was my thought as well.

I didn’t know if there was a second device somewhere that caused that delay when you feed AC to the RV. You know. Plug it in, turn on the generator, but whatever the power source, it waits a few seconds before connecting. Was suspicious of that.

I’ll check breakers first and wiring at distribution panel.

[enblethen]

I am guessing you have the truck camper with 30 amp shore power and no genset.
I would start by checking the connections in the 120 volt AC power distribution panel.
Pay close attention to the neutrals (white wires) in the back of the panel. I would suggest getting some electrical de-ox grease. Disconnect each wire, one at a time, check for brittle or melted insulation. If there is enough slack cut this portion off. Apply a good coat of de-ox grease, and re-terminate.
Check connections on the circuit breakers in the same manner.
Check the shore power connection in the small junction box. Make sure those are clean and tight. Coat connections in de-ox grease. Your cord may go straight to the 120 volt AC panel.
Careful about using the AC and microwave at the same time.
Check the cord body on the shore power cord for any signs of melting or black blades.

[time2roll]

Brownout as in low voltage? You will need to take some measurements with your voltmeter along the pathway.

Possibly just tighten all connections including at least the transfer switch and the breaker panel.

May want to start at the source when measuring voltage.

[Lwiddis]

They are wired up similar to a home.

[BFL13]

Not a clue, so ignore if wrong, but ISTR about air conditioners sometimes becoming increasingly difficult to start when cycling due to some kind of build-up. Can't remember any details.

Weird about the microwave!