Electrical issue on 50amp service

[WASTATELIVING]

I've got a new fifth wheel on 50 amp service. Recently we have lost power to all of our outlets and both electric fire places. After checking each plug, checking to ensure no breakers are popped, all fuses are intact, and the source is good this is what I've discovered.

The power supply cord is supplying 120v on both legs. When plugged into the RV our LED light above plugs shows power. At the breaker panel however, the red leg shows 120v and the black leg shows 70v. which matches the voltage I'm getting at the outlets. This is BEFORE it even reaches the breaker. I am assuming that the issue is in the inlet plug on the wall of the RV. Either a loose wire or it just needs to be replaced. I'll be opening it up tomorrow to take a look and replace it.

Any other ideas, something I might be missing?
Thanks
-Dre

[Bobbo]

Winnipeg wrote:
Power was OK all day until about 6pm, then the transfer started jumping in and out again and I saw volts go up to about 160. Yikes! On my dash to shut off the main I noticed the surge protector indicator lights were steady blue/green (normal) with occasional red (Open neutral).

A few simple tools revealed the problem. It's easy to get lazy about monitoring your connections, especially if you have never had a problem. But it is no fun doing repairs while on vacation.

Care to share the specific diagnosis and repair? You have implied a bad neutral, but that leaves a lot of possibilities.

[wolfe10]

Voltage to 160 STRONGLY suggests a bad neutral.

Suspect if you check voltage on the other line (L1 vs L2) to neutral or ground it would be LOW.

No idea if this is in your coach or shore power cord or in the CG wiring.

[Winnipeg]

Great discussion and information.

We are at an RV park and our auto transfer was jumping in and out last night. Never had a problem with it before so I disconnected for the night and used batteries and propane.

This morning I dug out a volt monitor (very handy, just plug in and look at it occasionally), and I noticed the power generally a little high, average 126v. We also picked up an inline 50a surge protector.

Power was OK all day until about 6pm, then the transfer started jumping in and out again and I saw volts go up to about 160. Yikes! On my dash to shut off the main I noticed the surge protector indicator lights were steady blue/green (normal) with occasional red (Open neutral).

A few simple tools revealed the problem. It's easy to get lazy about monitoring your connections, especially if you have never had a problem. But it is no fun doing repairs while on vacation.

BTW, we blew out a water line 2 years ago due to water pressure surge and not using a regulator. What a pain to repair that, not to mention no water for the remainder of the trip. And...I still forget to use the regular.

[Cummins12V98]

Had a neutral come loose and lay on a hot leg giving me 220V at the micro, smoked it!!!

[larry_cad]

wa8yxm wrote:
Yup. Just like me.. You HAD a screw or two loose. one of the same ones in fact.

Had weak (not open) Neutral at my house by the way.. That was fun. (NOT!!)

😉

[wa8yxm]

Yup. Just like me.. You HAD a screw or two loose. one of the same ones in fact.

Had weak (not open) Neutral at my house by the way.. That was fun. (NOT!!)

[Cummins12V98]

Great you found it!

[WASTATELIVING]

thank you all for your suggestions. It took me a bit to reply as I got off work finally this morning but we did find the issue. After checking all breakers, all connections, trouble shooting the inverter and separately testing each power cord and even hooking up to a generator the simple issue was a loose N and one of the Hot legs was also loose in the receiving plug on the exterior wall of the rv. ridiculous.

Thanks again for all your input, helped me believe I was on the right track.

Until next time,
Dre

[curt12914]

Have you tried unplugging and connecting (temporarily) through a 50 amp to 30 amp adaptor?
If you have power on both legs with the adaptor, you can narrow it down to a problem before it gets to the plug.
If you still have the problem with the adaptor, your problem is either in your power supply cord or in the RV.

[wa8yxm]

larry cad wrote:

vermilye wrote:
Check all the neutral connections. A loose or open neutral can cause different voltages between legs.

This is your problem. 70 volts almost always means an open neutral connection.

I would agree with you Larry if the other leg was not still showing 120 with an open neutral if one leg is 70 the other should be 170 so the total is 240..

This is why I think it's the low voltage leg that has a screw loose.

[larry_cad]

vermilye wrote:
Check all the neutral connections. A loose or open neutral can cause different voltages between legs.

This is your problem. 70 volts almost always means an open neutral connection.

[wa8yxm]

I will describe two issues and the likely culprits
One: You have 240 volts hot to hot and 120 l=hot to neutral (eitehr side) no load but when you turn things one. especially Heave eaters like the water heater or my lady's hair dryer or the nicrowave or one A/C the voltage on that leg goes DOWN and the other UP.. (Note a volt or two is not a problem 10 volts is) Open or high resistance NEUTRAL.

Your problem.. one leg stays at 120 and the other drops like a rock under load

Proglem high resistance that leg or way too much load

True story (Mine) When my rig was new sometimes one A/C worked, sometimes the other both or neither.. So i started tribble hunting (I'm a certified electronics tech) First stop was the breaker box (power distribution panel) also as it turns out, the last stop.

one of the screws holding the wires took over 3 full turns before I was happy. oh, yes once all (And I tightened every screw that turned) (UNPLUG FIRST) everything worked fine.

Other locations: The plug (Shore cord) Outlet (Shore cord) Inlet (RV) I had a loose screw on the inlet too.

Fellow RVer plugged his brand new sticker still in window 5er in and NO POWER.

Grabbed ye old multi meter (did not need it) and started diagnosis.. Shore cord outlet (The end that plugs into RV is called the outlet The "Socket" on the RV is actually an INLET (Plug) Fell off in my hand

The thing has 9 screws, 3 that hold the shell together and 6 that clamp the wires and cable. not one of those six had been tightened.

I've have loved to be there when the owner returned to the dealer for a "Chat".

Oh. I told him how much to bill (150/hr minimum 1 hr minimum) Though I did not bill (Fellow RVer after all)

[pianotuna]

Test the voltage to the transfer switch. Then test the voltage after the transfer switch.

I refuse to have a transfer switch. I use manual plugs instead.

[Dutch_12078]

dougrainer wrote:


PS, I have 42 years as a RV tech and one thing I have learned over those years is that even LICENSED ELECTRICIANS, have problems understanding 30 and 50 amp RV plugs.

If the electrician doesn't understand how to wire a NEMA 14-50R for a 50 amp RV, find another electrician. The wiring is identical to the NEMA 14-50R for a residential range.

30 amp is a different story. For some reason some electricians can't read the "120-volts" label on a NEMA TT-30R outlet and confuse it with wiring the "120/240-volts" NEMA 14-30 outlet, or the "240-volts" NEMA 10-30 outlet used by older dryers.