Uneven voltages on 50 Amp

Loose or open neutral. Check all neutral connections from the house's load center to the dedicated 50 amp receptacle. Also a good idea to check continuity along the entire path.

larryt1939 wrote:
Thanks for all the replys. This is a Jayco 5th Wheel, 2007. I just went and checked for the jillionth time that there is 120 on both sides and 240 between them. At the disconnect in the garage and the recept at the end of 50 amp direct burial. Checked continuity on 50 amp cable and in breaker box inside the RV. 240 across main breaker 120 from each side to neutral. WA3YEY@yahoo.com

Be sure to check the suspect branch by connecting an unbalanced load to each of the hot-neutral branches at the receptacle at the same time.

If the neutral is bad up to the receptacle, the voltage will vary.

If the voltage doesn't vary, then the issue will be in the camper or camper's cord.

Thanks for all the replys. This is a Jayco 5th Wheel, 2007. I just went and checked for the jillionth time that there is 120 on both sides and 240 between them. At the disconnect in the garage and the recept at the end of 50 amp direct burial. Checked continuity on 50 amp cable and in breaker box inside the RV. 240 across main breaker 120 from each side to neutral. WA3YEY@yahoo.com

I had this problem at my house a few years ago. I called the power company and they had someone out within the hour. It's a serious problem. They ran a temporary neutral from the transformer to my breaker box. Then about a week later they came & ran new cables from the transformer to my breaker box. Don't mess with it...call the power company.

Found this great PowerPoint that does the math and shows how an open neutral causes voltage variations on both legs.

Corrected. The side blades should have 120 volts to the bottom blade(neutral) and top blade (ground).
There should be near zero resistance between the top and bottom blades in the pedestal.

It's open or weak neutral. The low side has the heavier load on it.

enblethen wrote:
Problem could be in pedestal.
You need to start by checking the pedestal or where you are plugged in. Verify that the two parallel blades have 240 volts between them.
If you have a genset with automatic transfer switch the neutral contact could be an issue.

You were right the first time, it's an open neutral. OP will get 240v measured between the two hot legs, what he won't get is 120v measured between either hot leg and the neutral.

The problem could be in the rig's power box, check the neutral connection. Then check the cord/plug, then the pedestal, keep going upstream until you find the problem. If you are having problems with other home appliances it could be a power company problem.

This is a good 2 minute video demonstrating what happens with an open neutral.

As said UNPLUG IMMEDIATELY (or expect significant repair costs).

Find and fix the open neutral.

Test it, THEN plug back in.

If in a CG, check at another site with a volt meter.

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