Strange electrical problem please help

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Kyler

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Georgia
New to the forum and just wanted to see if someone had any insight on a problem I'm having with my camper . I have tried about everything and cant seem to find my issue. 08 montana 3600re 50a I travel for work haven't had any serious issues with this thing till I got to a new campground last week, when I set up and plugged in shore power I I turned on my ac units they ran for a min or so and tripped the breaker. Then I just turned one on and it ran a short time and then slowed way down before finally tripping again. Coils and filter are clean and I'm in the shade. But when I turn on the fan only it run all night. Here is where it gets strange I turned all breakers off except the ac then turned it on ran a short time then tripped. Turned that ac breaker off and turned the front ac breaker on and ran it and it did the same way. Then I turned breakers back on and checked my wall plugs with ac off 138 volts that's not good. I left the meter on the wall plug turned my ac on and huge spike in plug to 158 volts then a gradual climb till the ac slowed and that point my wall plugs were 179 volts in the back of the camper and the front plugs loose power to around 70 or so volts. I am so confused and burning up in the afternoon trying to fix this after work everyday and insight would help
 

Kyler

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Georgia
At the pedestal i checked the two hot legs and one is 125v other is 120v they seem pretty close to specs but I also am using two 30a plugs into a my 50a it's like a 3 way adapter. But I checked my buddies a few rows over and we swapped adapters and mine worked fine on his camper so I ruled out that it was the adapter.
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DonTom

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179 plus 70=249 VAC. ~240 VAC between them?

Seems to me that your adapter is causing a weird issue in your RV only. But not sure why. Perhaps a defective 120 VAC item is causing it. I would start turning off breakers until you see 120 VAC on each side.

Will it be normal voltages if you plug into a 14-50R or a 30 amp without your adapter?

-Don- Auburn, CA
 

Kyler

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I tried it on a single 30a already and it did the opposite. Wall plugs had 110v on them then I turn ac on and they dropped to 80 something then ac unit tripped the breaker.
 

Gary RV_Wizard

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The poor quality or open neutral causes the voltage to vary with the load, so the no load voltage can be fine but it goes wild when a substantial load (like an a/c compressor) comes online.

I'm not clear on this Y-adapter you are using and why. Does it split a single 50A outlet into two 30A outlets? Or are you using getting power from two 30A outlets and the RV shore cord plugs to a 50A outlet on the Y-adapter. I'm familiar with all the variants of a Y-adapter - just trying to figure out which one you are using and why. If you have a 50A RV and a 50A outlet on the site pedestal, there would be no need for an adapter, right?
 

Kyler

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Georgia
Sounds more like the campground pedastel has the problem . My 1st thought , Bad neutral since you are seeing 169 volts. Unplug the rv & check pedestal.

The poor quality or open neutral causes the voltage to vary with the load, so the no load voltage can be fine but it goes wild when a substantial load (like an a/c compressor) comes online.

I'm not clear on this Y-adapter you are using and why. Does it split a single 50A outlet into two 30A outlets? Or are you using getting power from two 30A outlets and the RV shore cord plugs to a 50A outlet on the Y-adapter. I'm familiar with all the variants of a Y-adapter - just trying to figure out which one you are using and why. If you have a 50A RV and a 50A outlet on the site pedestal, there would be no need for an adapter, right?
The pedestal I'm at has no 50a hookup just two 30a. I'm using a two 30a to one 50a adapter but I put the adapter on a buddies camper on a different row and his camper works fine .
 

Lou Schneider

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It's called neutral swing and means you don't have an adequate neutral to keep the 240 volts divided into two 120 volt circuits when one side is loaded more heavily than the other. If the neutral is weak it will "swing" towards the side pulling the most current, robbing voltage from that side and adding it to the less lightly loaded side so the total still equals 240 volts. This explains why you're seeing 170 volts on some plugs and 70 volts on others, depending on which side of the incoming feed they're on. The air conditioners are on the same leg as the outlets showing the low voltage and the low voltage is making them draw more current, tripping the breakers.

Since your twin 30 amp adapter works OK at your buddy's site, it suggests the problem is in the system feeding the pedestal at your site. Keep in mind you're using power in a way that might not have been anticipated by the campground designer.

You're fortunate in that you have outlets on both legs of the incoming AC power, giving you an easy way to monitor the incoming AC voltage. Running the air conditioners on less than 108 volts will shorten their life, even if the increased current isn't enough to trip their breaker. If you don't want to invest in an energy management system that automatically cuts the power when the voltage gets out of spec, at least get a couple of plug in voltage meters and put one in an outlet on each leg so you can be aware of a problem.
 

Mark_K5LXP

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Highly recommend you resolve this conclusively. You can totally wreck some expensive equipment if you don't. I would be unplugged at this point pending resolution, whether that's an effected utility repair or relocation to a functional pedestal.

Mark B.
Albuquerque, NM
 

Kyler

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Thanks for all the input I will move sites when I get off work and let you know what I've found
 

John From Detroit

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I have a polarity tester and used it in the camper and it is saying that the plugs are correctly wired and ideas how this is possible? I also tried it on the pedestal
That is easy the tester uses way way way less than 1 amp. the air conditoner around 13 (well over 1000 times the power. the neutral i not "open" it's Weak.. NOTE I am assuming this is a 50 amp rig.

WHY is this so.
Think of electricity as water.. Flowing through a pipe
Pump1------------T--------Pump 2 (Water flows to the right)
So long as pump one is pumping the same amount of water as pump two. the "T" neither draws in water nor spits it out.
In this case the "pump" is your air conditioner.. It draws a lot of water So depending on wich side ot the T this excess flow has to go either out the T. or Water needs to be sucked in to make things work.

The electrical version
50 amps is 120-0-120 volts (Technically Volts are pressure... amps are gallons per minute(
An air conditioner. water heater or other 'big ticket" item will use one of the 120's.
If the RV's load is perfectly balanced. then no current flows in the neutral

But if just one leg is heavily (Compared to the other) loaded the neutral makes up for it
If the neutral is not 'strong' then the center voltage moves

you saw one leg go to 138 Thus indicating a bad (not completely open but bad Neutral.
 

Kirk

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The first thing to understand is that with a 50A RV cord what you have is 2 hot leads, L1 & L2, each one capable of carrying 50a and that they are of opposite polarity so if each leg has the same current draw that current goes between the two legs and no current is on the neutral. With 2 perfect 30A outlets and all working properly you could never get more than a total of 60A or only 10A more the one leg of your 50A cord.

Another important factor with your problem is that with an alternating current motor, as the supplied voltage goes down the amount of current (amps) increases so if you lower the voltage by 25% you it now requires 25% more current or amps. It is a basic principle of alternating current motors. Mix these two items with the unknown of the electrical panel and it becomes a very complicated situation.

If you are going to use one of the cheaters like you have the first thing that you need to do is to take your meter and measure from the hot let of one plug to the hot leg of the other and expect to see a reading of 240V. If that reading should be 0V it means that they are the same phase leg. Next take that same reading from the neutral leg of one outlet to the neutral leg of the other. It should read 0V. If it reads any significant voltage there is a neutral problem. You should probably do the same between the ground pins of each outlet, again looking for 0V. Those are the proper readings.
 

Kyler

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Georgia
I moved sites and my problem is gone everything is working as it should I am grateful to all of yall that help I was about to go crazy trying to figure this out and taking everything apart. Ac blowing cold now with 119v on my wall plugs all of them are within 1 or 2 volts. Thanks guys. It was a bad nuetral at the pedestal.
 

John From Detroit

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Thus proving it was a park side issue.

You really should invest in a good Surge Guard say a Progressive Industries HW-50c with remote. They really help when thing like this happen.. Mine diagnosed a few park side issues for me.
 

Ex-Calif

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I moved sites and my problem is gone everything is working as it should I am grateful to all of yall that help I was about to go crazy trying to figure this out and taking everything apart. Ac blowing cold now with 119v on my wall plugs all of them are within 1 or 2 volts. Thanks guys. It was a bad nuetral at the pedestal.

I do hope that the park owner is advised and is gonna get it fixed.
 

Gary RV_Wizard

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The pedestal I'm at has no 50a hookup just two 30a. I'm using a two 30a to one 50a adapter but I put the adapter on a buddies camper on a different row and his camper works fine .
That introduces more variables. The two 30A outlets may different phases and when combined can yield 30A @ 240v, or they can be in-phase and yield 60A @ 120v. And there are two neutrals, one at each 30A outlet, but they are tied together in the adapter. The other site is likely different than the one giving you problems.

I see that Kirk has already explained how twin-30A differs from 50A, so I won't belabor the point further.
 

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