New 5th Wheel Seeing 250V on 50A Shore Power

[PastorD]

Hello fellow RVers! My wife and I purchased a new 2026 Forest River Prime Time Crusader 5th wheel. We are using it full-time living at the new church we are pastoring. The church has a full hookup with 50 amp service. We arrived with the RV two weeks ago, plugged into shore power and were up and running. Six days later, we had a power issue. Several of our 120 volt lamps went out, our Furrion Chill Cube fried a control board, a small fan burnt up, and our clothes dryer fried.

We had an electrician come and check the shore power and all checked out well. He also checked our power cord from the outlet to the RV all volt readings were good. I also performed an Ohm test on the power cord and it tested OK.

I installed a 50 amp surge suppressor at the outlet confident that all was well. This past Sunday, it happened again! Even with the suppressor! Lights went out, dryer fried again. I had a volt reading of 250 volts on one of my inside outlets as the surge was happening. The surge suppressor has indicators for open neutral, and they showed OK. It also has voltage indicators for each leg, and they were reading 124 and 125 volts respectively. Also, the GFCI in the bathroom was clicking... I think the AC is ok... We unplugged the shore power, cut off the propane, and left for a hotel.

This is discouraging with a brand new RV that we've only been able to use a few nights...

Sorry for the long post, just checking to see if anyone has any ideas. We have a mobile tech scheduled, but I was wondering what I could be checking in the mean time.

Thanks for any suggestions!

PastorD

 

[OldWEB]

The surge suppressor has indicators for open neutral, and they showed OK.
Trust the surge suppressor, it sounds like an open neutral, which is very dangerous to the equipment. What showed OK?

 

[PastorD]

Thanks so much for your response! The surge suppressor has indicator lights built in that show items like open neutral, open ground, etc. All these were indicating that all was well and that the neutral wasn't open, etc. It also has 2 voltage readings that are constantly taking readings of both 50 amp legs. They were reading 125 volts each at the time of the surge.

The surge suppressor does plug in directly to the 50 amp shore power outlet. I am using a 50 foot RV connecting wire with the twist lock between the shore power outlet and the RV.

My electrician checked the cord for correct voltage and all was OK.

I Ohmed the cord last night and it had no open wires.

I have pulled the twist lock connection off the outside and verified the tightness of the wires on the back.

I pulled the front off the power center inside the RV where the 120 volt breakers and 12 volt fuses are and all the connections to the inside 50 amp breaker and the neutral and ground are fine.

On a side note, the 12 volt system is working OK thankfully.

Thanks!
PastorD

 

[boatbuilder1]

You need to check all the connections where the shore power meets the power center. From what I know of surge suppressors, they only monitor upstream of them not downstream. So if the issue is between the suppressor and the panel it will not be detected.
Finding 250 volts at an outlet is a very good indication of a problem with the neutral.

 

[bigbAZ]

@boatbuilder1 nailed it, this points to a problem after the surge protector, very likely a neutral problem as indicated by the high voltage at the receptacle. A high load such as a shop vac can expose a compromised neutral, did your electrician put things under load?

 

[Gary RV_Wizard]

All your symptoms point to a "open neutral" issue, which allows the two line voltages to vary any where between 1 & 240v as their individual amp load changes. That will indeed cause serious power problems. You have to do the line voltage measurements as the amp load changes - measuring after the fact will miss the problem.

Based on your report, it sounds like the problem is between the surge device and the RV's load center, e.g. the shore cord plug, it's connection to the RV, etc. It's even conceivable that your neutral will show continuity with an ohmmeter but be unable to pass enough current to balance the two hot legs. A loose or badly corroded connection can cause that.

 

[Arch Hoagland]

PastorD...Who installed the 50 amp outlet you are plugged into?

 

[CharlesinGA]

What is the brand and model of the "surge suppressor" you have.

Your voltage is a tad high. 125 v is the max on each leg, I'm used to seeing 120-121 volts usually.

On a new RV of any sort, you should always remove all power, turn off the battery, and then open up the power center covers, expose everything. Tighten up all terminals on the circuit breakers, the ground bar, and the neutral bar, and in addition, if the 12 volt connections are screw terminal, tighten them also. Some of the new ones are using the WAGO lever type connectors on the circuit boards, in which case it would be worth taking each one and opening it, making sure the wire is stripped, and then putting it fully back in the connector and closing the lever. Also for 12 volt there should be a terminal stud or bar for the grounds of the 12 volt system. They all need to be tight. If you have an inverter or other electrical equipment, transfer switches, all of this should be inspected and all terminals tightened. Every year, go back thru and again check the tightness on everything. It gets loose rolling down the road, vibrating.

You really need an EMS (Electrical Management System) that will monitor and shut off if you experience High or low voltage, open neutral, neutral and hot crossed, etc,

Hughes Watchdog

Progressive Dynamics EMS-PT50X

Southwire Surge Guard

Hardwired versions of these can be installed in the RV so you never have to deal with plugging them in.

 

[John From Detroit]

Open neutral can happen in several places..
In line order Before power even enters the Building (Church) Happened to me at my house.
Every connection from meter to box, in the box. (Breaker box) at the outlet.> I'm guessing that's not it.

The plug.. (RV's plug) I once had a brand new STicker in window new parked next site with power problems ALL the screws in the plug not tightened. the plug came right off the cord. We fixed it.
But I'd have loved to bed a fly on the wall when he got back with the dealer (Evil grin).

If the cord is detachable.. There is the outlet on the cord and the inlet on the RV.

if you have an auto transfer switch that's 3 points of failure.. Line connection Load and the contactor

The breaker box in your RV (main ground board) I had multiple screws loose in my breaker box.

I have enough training to feel comfy working on my own stuff so I fixed it.
(Same for the guy with the lose plug above he was also skilled)

 

[PastorD]

Thanks so much for all this input! The shore power outlet was installed correctly, but I'm not sure who installed it. It has proper gauge wire and all terminals are tight (checked them myself). I also had the power company out after the first surge to check power going into the meter and panel box. All looked good per the lineman.

The electrician who came to check it out said a reading of 125 volts is common as the transformers for the building where the shore power connects are quite near. It comes in from overhead.

The lineman did say we were near transmission lines, and lightning strikes on the lines were common. We accepted this as a possible cause of the first surge, but the second had the surge protection in place.

I don't have the brand of the surge protector at the moment. It got very good reviews...

We didn't test with a load at any point. We tested for voltage in the panel box, voltage at the plug (across all points: leg to leg, legs to ground, legs to neutral). Tested the same at the plug on the RV end of the cord.

I checked the connections on the 50 amp breaker on the RV's inside panel box. Also checked the neutral wire and ground in the inside panel box. I didn't check each circuit. Will plan to do so.

We don't have an automatic transfer switch for the generator.

We do have a reputable mobile tech coming out in a couple weeks. Until then we have other accommodations.

Thanks again all!

PastorD

 

[John From Detroit]

The outlet was installed improperly?? Yet the electrician got 125/125.. Strange.
NOTE 125 is within range A bit "Warm" but not overly "Hot"

On your surge supressor not only make but model please.
I know two major and a couple lesser brands.. All make Very Good units.
And Rather cheap units that are not nearly as good.

 

[Gary RV_Wizard]

125v is at the high end of the acceptable range, but unusual enough to make me want to investigate further. Everything the lineman told you is true enough but doesn't totally rule out a problem. The fact that you had electrical damage in your RV ought to be proof enough there is a real problem somewhere, but the problem may not be with the 50A outlet or the local power source.

 

[bigbAZ]

Since he measured 250V on a 120V outlet "while the surge was happening" I wouldn't call this a surge at all, surges typically last nanoseconds, this is more a "condition" than a "surge". Everything points to a neutral problem under load. He said the electrician did not test anything while under load, which is incomplete troubleshooting.

 

[PastorD]

A load test is on our radar. I will ask the tech when he comes to do that.

The first episode we had was with 2 ac's running. The episode Sunday evening was with NO ac's running and just 4-120 volt lamps on in the RV. Three of those have LED bulbs (low draw).

I attached a screenshot of the surge suppressor we bought...hope it is a decent surge suppressor...

Can someone enlighten me on an EMS system? Does it just plug in like a surge suppressor, or is it a different item entirely? I am thinking that once we get this figured out and get this behind us, we may want one!

 

[John From Detroit]

Mine showed up when an AC kicked in.
Suggestion if you use the AC to test under load.
Kill all brekers that feed anything electronic. A fan is ok, or a outlet occupied only by the volt meter.,
But no power to fridge, TV, Converter, Radio or anything 120 volt electronic.

 

[bigbAZ]

The best way I found them was to hook up my big shop vac while probing L1 & L2, if the neutral is compromised the legs will noticeably go off balance as soon as the shop vac starts.

 

[RayIN]

I suggest you check all the electrical connections inside your main breaker panel. If you are not sure of yourself doing this, hire an electrician. Another place to check connections is inside your ATS=automatic transfer switch.
Things shake loose in all RV's while traveling our wonderfully smooth highways.

 

[PastorD]

Thanks again to all who have responded with help! I do suspect a weak neutral somewhere in the system. We have a RV mobile tech coming the 16th, and I will post back with his results after then.

Blessings,

PastorD

 

[Gary RV_Wizard]

I attached a screenshot of the surge suppressor we bought...hope it is a decent surge suppressor...

Can someone enlighten me on an EMS system? Does it just plug in like a surge suppressor, or is it a different item entirely? I am thinking that once we get this figured out and get this behind us, we may want one!

That's a decent unit except that it doesn't shut power down if the voltage goes out of acceptable range or if neutral or ground is lost. If you aren't watching the display at the moment something goes wrong, you won't know what happened.

An EMS can be either hardwired or portable (plug-in), but it takes protection to a higher level. It both monitors in real time and automatically removes power from the RV if it gets outside of the safe range, showing an error code to identify what occurred. An EMS will be more expensive (about 2x). Here's an example.

 

[PastorD]

OK, so I may have made a discovery today. I glanced at the electric meter on the building our RV was connected to. It is a digital meter. It was displaying a " CA Diagnostic 3" code which when I researched means that one of the three legs of the three phase system is not operating correctly. Perhaps not functioning at all or low, etc.

Further research says that if one leg out of the three is out of range, it corrupts the power on the other two legs perhaps causing a surge.

I would have thought my surge suppressor would have prevented the surge but...

Any thoughts?

Thanks All!

PastorD