Electrical help needed! Lost 50 amp shore power. Is it the power cord?

[bertschb]

I still think that the RV end of your 50A cord is the problem. As the cord warms up, it deforms until one line connection is lost. At least . . . that would be my theory .

Here's one more piece of information that may be relevant.

The sun hits the power cord where it connects to the RV early afternoon. Maybe 2:00PM? I actually taped a white piece of cardboard to the side of the RV at noon to block the sun from hitting the cord/inlet directly. It didn't work of course but it was worth a shot.

[TedS]

I think the park needs to investigate from distribution panel to post. The system does not seem to be able to support increasing load as the day goes on.

[Cate&Rob]

The 240V park power is not divided into the two 120V legs until it gets to the circuit breakers in the post. It is possible that a breaker is faulty and one side is dropping out. When one leg drops out, check across the two side terminals (carefully!) of the post outlet for 240V (or something close). If there is correct voltage here, the problem is likely the cord. If there is no voltage here, the problem is likely the post breaker. You can further check the post outlet for 120V between each side terminal and the lower center terminal. The slot which is the neutral, not the U which is the ground. If you are not comfortable checking this kind of voltage, perhaps the park electrician can test at the post (without touching the breaker) when you see one leg dropped on your EMS.

Rob

[bertschb]

We're leaving this park in a couple hours so I won't be able to test the post. Unfortunately, our next stop is a park that may have low voltage issues. My wife learned this while reading reviews yesterday. That won't help my troubleshooting. But, we will be at Zion National Park on Wednesday and staying for a week. It will be hot so that should be a good test of the power cord - especially if the afternoon sun hits the street side of the RV.

The good news is I can use my 30 amp cord if the 50 amp cord fails again and with the Power Assist feature on my inverter, I can run both air conditioners no problem so it's really not a big deal. Sourcing a SmartPlug kit while on the road has been a challenge. I may make some phone calls this afternoon when we arrive at our next destination (Salt Lake City) to see if anybody has it in stock.

[Jims94vmx]

Swap the breaker. We had a situation at the park I am workamping. He also was not getting power to both lines. When testing the breaker it showed 120 on both.....swapped out breaker and all was good.
Easy thing for park to do.

[TedS]

The 240V park power is not divided into the two 120V legs until it gets to the circuit breakers in the post. It is possible that a breaker is faulty and one side is dropping out. When one leg drops out, check across the two side terminals (carefully!) of the post outlet for 240V (or something close). If there is correct voltage here, the problem is likely the cord. If there is no voltage here, the problem is likely the post breaker. You can further check the post outlet for 120V between each side terminal and the lower center terminal. The slot which is the neutral, not the U which is the ground. If you are not comfortable checking this kind of voltage, perhaps the park electrician can test at the post (without touching the breaker) when you see one leg dropped on your EMS.

Rob

Rob, the 240v is split at the transformer, not at the post breakers. The two 120v lines are then fed to the park distribution panel(s). From there to the site posts. The transformer needs to do the splitting, not the breakers.

Yes, replacing a site post circuit breaker could fix the problem. Happened to me at a campground. One leg of the circuit breaker failed

[Canyonlight]

Brian bertschb - you and much of the west are experiencing record heat and energy demands. Is the power grid the issue, being strained to the max thus affecting not only your RV park and thus your 310 but negatively impacting electrical in many many areas of the west ? In other words, your 310 and RV electrical system is fine but your being impacted by grid electrical issues/brownouts/power system "rationing."

Dan

[bertschb]

Is the power grid the issue, being strained to the max thus affecting not only your RV park and thus your 310 but negatively impacting electrical in many many areas of the west?

Hi Dan. That's possible. It was in the low 90's when the voltage dropped out so not too hot where we were staying (relatively speaking) but I'm not sure how our area was tied to other parts of the grid like OR and WA where they had all time record heat.

We just arrived at a park in Salt Lake City where L1 is 107v and L2 is 110v. My EMS will shut power off at 104v so I'm right on the edge. But as I mentioned in my previous post, low voltage is a known issue at this park. It's 1:30 PM here at 88F degrees and heating up. I wonder how long we'll have power today?????

[Cate&Rob]

bertschb Canyonlight

The situation with L1/L2 @ 107V/110V is indicative of park system overload. Both legs drop more-or-less together until one trips the 104V EMS threshold. This is the classic "brown out".

The situation that Brian encountered at the previous park with one leg normal and one leg gone indicates a wiring problem. The park?, or the power cord?, or the trailer? If it doesn't re-appear, it was the park. If it does, it is likely the cord since using the 30A cord solved the problem.

Rob

[Canyonlight]

Thanks Brian bertschb and Rob Cate&Rob for your responses. Most of you here know that I did not even play an electrician on TV. Heck, they wouldn't even let me read the script ! I have basic understanding but have learned so much from many of you here who are really well versed.

It is just interesting that a trending number of posts regarding electrical challenges here on this forum an elsewhere have been showing up the last several days particularly in the VERY hot west of the Rockies area from Canada to the South Pole. Coincidence or could there be some strange things going on impacting various electrical systems in the RVs.

Extreme and persistent hot or cold conditions conditions can do some strange and potentially damaging things. Thank goodness for our electrical well versed folks here to help diagnose and correct challenges !

Dan

[TedS]

The 30 amp connection that worked may have been on the park leg that was not the problem leg.

[howson]

The 30 amp connection that worked may have been on the park leg that was not the problem leg.

That's the interesting part of this discussion I've been trying to wrap my head around. The 30A adapter ties the two legs together, right, as shown in pic below? (Graphic below from RV.Net forum.)



Since @bertsch had success with this adapter, the bad leg must have been "open" somewhere.

The conclusions are still the same--park has an issue (somewhere from the output of the transformer to the output of the pedestal) or Brian has a bad cord or receptacle on his trailer. If either of the two latter are the issue, we'll find out soon enough. The cord (or trailer) won't get better all by itself.

Howard

[TedS]

The 30 amp post outlet uses one of the two 120v legs at the post. If L1 is the same as 30 amp line, then the L2 in the post could have the problem. Or the 50 amp breaker on the post could be bad.
You are correct about the adapter connecting the one 30 amp hot to the two 50 amp hots.

[howson]

Misread his original post (again). He swapped the entire cord, he didn't just add an adapter. That implies there was a separate 30A connector on the pedestal. So there's a few variables still in play -- different cord and different outlet on the pedestal.

[bertschb]

He swapped the entire cord, he didn't just add an adapter.

Correct Howard. I have the factory 50 amp cord as well as a 30 amp cord with a 30 to 50 amp adapter. The 30 amp cord was plugged into a separate 30 amp outlet on the pedestal and worked for two afternoons/evenings with no problems.

To recap today- We arrived at this new park today at around 1:00PM MT. Voltage at this park is known to be low based on reviews from other guests. The weather conditions are similar to the last couple of days in Idaho. Low 90's and the afternoon sun is directly on the power cord.

I plugged in the 50 amp cord and these are my readings so far:

Monday June 28th
1:00PM L1-107v L2-110v
2:15PM L1-108v L2-110v
5:00PM L1-106v L2-113v <------ My EMS cuts power at 104
6:30PM L1-110v L2-111v
8:30PM L1-110v L2-114v

50 amp cord worked fine all day and night

Tuesday June 29th
6:00AM L1-119v L2-121v
2:00PM L1-107v L2-111v
2:30PM - Lost power for a split second. EMS showed PE4 error (low voltage on L1)
4:00PM L1-108v L2-107v