Voltage Varies Inversely with Microwave Use

[amron]

We use a voltage monitor in our RW. Whenever we use the microwave, the monitor shows an increase in voltage. Normally we would see a decrease in number showing how much voltage the appliance draws. This only happens with the microwave, other appliances are ok.
Any similar experience? Will this damage our microwave?
We have a 2012 FB.

[atom ant]

Best thing to do is stop looking at the monitor Too much information is bad.

[travelin' texans]

I agree with Brad, if you didn't see it, it didn't happen. Also the wiring on rvs are like their tires, suspension, & several other components, just barely enough to meet minimum requirements.

[spindrift]

There is an inverse relationship between current and resistance. Ohm's Law...I think.
Either that or your monitor is broken. 😁

[tangoparson]

The only thing I can think of that might cause a similar symptoms is a “loose neutral “ condition. That can cause some seriously wonky voltage readings, usually one leg goes high and the other leg goes low. Most higher end monitors would catch that though. My progressive will.

Maybe not truly loose but a high resistance


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[amron]

Thank you all for responding.

Sounds like nobody else had similar experience. This past weekend, there was a strong smell of burning electrical insulation at 3:00 AM. and we looked all over the RV for any sign of smoke, etc. I noticed the microwave clock was reset to zero which meant there was some interruption sometime during the night, although the coffee maker clock was not reset. Yesterday, after using the microwave, there was a beep then the clock was reset to zero.

[Highcountrybarry]

The microwave should be plugged into an outlet above or beside the microwave. I would unplug the microwave and test that outlet first. If you don’t have equipment to check it plug in a high draw appliance like a hair dryer and see what results on the volt meter. If you can determine the outlets is not the issue then work on getting a new microwave. To tango’s point, there may be a loose neutral in the outlet. Smelling electrical components producing heat is no joke, most especially in the middle of the night. If you have any doubt have a qualified electrician check it out.


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[amron]

Barry,
With your good guidance, we plugged a hair dryer into the microwave outlet - voltage climbed.
We then plugged the hair dryer into a different circuit outlet - voltage dropped.

Since the microwave has it's own circuit breaker, we should be able to check that wires are tight in the breaker box. If that doesn't solve the issue, we'll tighten the wires at the receptacle. There should be NO connectors between the box and the microwave outlet.

The smell of the burning insulation was strongest at the steps, right beside the breaker box. My guess then is that the issue lies in the box.

Thank you for your good help.

[Jim & Mary]

Not necessarily so. Our 2013 36RL had a power loss to the RV fridge on our way to AZ in 2014. I was able to plug the fridge into an extension cord till we got to AZ to troubleshoot. Our research led us to two splices between the circuit breaker box and the microwave outlet. Our RL has three circuits in the kitchen slide, and while I don't know for sure yours is like ours, I suspect it is.
The 3 circuits are:

1. Fireplace
2. Microwave
3. RV fridge, stove outlet, entertainment center.

The romex from the breaker box mates up with the flexible cord that enters the slide at the street side rear of the coach so it can take the repeated extend/retract of the slide and enters the slide behind the left bottom drawer next to the fireplace, where it splices into romex again to travel up to the microwave outlet. Yours may not be like ours, but it's a place to start. The first splice utilizes what electricians call an Anderson plug, and in our case that's where the problem was. I'll try and attach pics to show. This is located to the rear of the rear of the slide on the street side above the plastic film sheeting. Shouldn't be too hard to find.

[Highcountrybarry]

Looks like you are on track getting it isolated. Of course Jim is spot on, you will need to trace out the entire circuit. Starting at the panel is probably a good idea. Hopefully there is no serious damage. Good luck and let us know what you find!


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[travelin' texans]

There won't be much tightening at the MW receptacle, they are very cheap press in slots, if its bad replace it, if there's room put a real receptacle.

[amron]

Thanks for your detailed advise, Jim. We'll keep you all updated as soon as we have worked on it probably after the holidays. Right now we have unplugged the micro and are visiting with family.

Hope y'all have a Happy Thanksgiving!

[Colorado]

Any idea where these are on a 2013 36 RE?

[Jim & Mary]

I would speculate that year RE was essentially the same, but the power cords for the microwave might enter the kitchen slide at the front of the slide instead of the rear. Look for black covered rubber cords on the hanging looms that flex when the slide is extended/retracted.

[Colorado]

Thank you. I will check it tomorrow.

[gflynn]

There located under the drawer below the fridge