This is so strange..Plugged in to 30 amp shore power. Went to use microwave. As soon as the magnetron fires up, the lights and control panel on the microwave dim to the point of not working.Used an extension cord to plug the microwave into another outlet in the RV and it works fine.I figured it was loose wiring in the outlet, (sometimes those wires come loose from the crimp), but that was a no-go.Now the strange part. If I fire up the generator, it all works well.No other outlets in the MH are affected, just this one.Any Ideas?Dan

Sounds like a problem with the pedestal. Re-cycle the 30 amp breaker, make sure both sides are on and if still fubar, call the park manager.

The microwave may be a thousand watts potential. Use the DW's hair dryer to approximate the same degree of load on other outlets.

Check the wire connection at the breaker (and the breaker itself) for the Microwave circuit. From the way you describe the issue it pretty much narrows it down to that area.

OK. Got a hair Dryer, works fine in all outlets EXCEPT microwave outlet. Will work on fan only, but as soon as you kick on some heat, It acts like the microwave did. Slows down to nothing. all other outlets in RV are fine.Not a pedestal problem, as I am back home and still acting the same.Will check tomorrow on the breaker issue, but not holding out much hope on it. The outlet works fine on Generator, just conks out on shore power.Thanks for everyones input! Truly appreciated.Dan

Some rigs have the microwave and water heater on the same branch circuit and use an energy management device to make sure the two devices don't overload the circuit when they both want to run. If you have one of these devices, that's another thing to be suspicious of. The generator vs. shore power behavior difference is very mysterious, however.

Strange electrical problem | Good Sam Community

mrekim
Explorer
May 21, 2015
It would be helpful to know what devices are on that circuit. For example, in my trailer the microwave is on the same circuit as a built in electric heater.

There is a switching device that turns off the heater when the microwave is in use.

If something like this is part of the picture we need to ensure that the other loads on that circuit are turned off when testing.
jrnymn7
Explorer
May 21, 2015
Wouldn't shore power and genset power go thru the same 120v breaker panel, and then to the various outlets? Or does genset power bypass the breaker panel and go direct to the receptacles? (or at least to certain receptacles).

If shore power has low voltage, that should effect all receptacles, not just the one the microwave is plugged into.
Bobbo
Explorer II
May 21, 2015
I would check all connections at the outlet, and at the breaker box for HOT and NEUTRAL wires for that circuit. Sounds like a loose connection. I bet the NEUTRAL wire is loose in the breaker box.
pianotuna
Nomad III
May 21, 2015
Hi,

Did you check at the circuit breaker for a loose wire or not tight screw? Can you see any discoloration on the buss bar in the power distribution box?
Chandalen
Explorer
May 21, 2015
The OP said that plugging into another plug -in the RV while on shore power- fixed the problem.

Also said that on a genny the problem does not exist.

The problem is the microwave circuit.

My theory is the shore power is low to begin with and the genny power is where it should be. That would mean there is a voltage drop when the microwave kicks in.

The question is why?

Can you plug in a multimeter in the same branch as the microwave and see what the voltage drops to when its off and on?
down_home
Explorer II
May 21, 2015
Low voltage. First check the power from the pedestal. The hair dryer might work better because it doe not demand as much power.
When you gen kicks in you are getting full power.
Check the switch and wiring , brain freeze, that switches between shore and gen and trace wiring if necessary to fuse or breakers, then to where microwave is plugged in. Doubt it is plug as you have full power with gen.
nineoaks2004
Explorer
May 21, 2015
You did not state the size of the extension cord you are using. If it to small the voltage drop could cause this problem.
mrekim
Explorer
May 21, 2015
Do you have a means to measure AC current - KillAWatt or clamp meter with an adapter for the outlet?

Also, is there anything else on that circuit?
MEXICOWANDERER
Explorer
May 21, 2015
Does the rig have a load management or load shed "center"?

First place to look is voltage at breaker, and then look to see if the factory did something weird with the neutral connection.

Lost AC power. I'm down at the store and I have around ten minutes before the Infinitum server UPS falls flat on it's face...

Good Luck
road-runner
Explorer III
May 20, 2015
Some rigs have the microwave and water heater on the same branch circuit and use an energy management device to make sure the two devices don't overload the circuit when they both want to run. If you have one of these devices, that's another thing to be suspicious of. The generator vs. shore power behavior difference is very mysterious, however.

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