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Bizarre over-voltage on Shore power?

Yahoo Message Number: 110789
I am fairly handy with electricity but I am stumped on this one:  I am plugged into 50 amp but I am seeing up to 130 volts on one leg on my AC feeder panel (as well as the readout on my Progressive EMS which is cutting the power when it hits 131). The voltage varies as loads change. As the one leg goes up 130, the other drops down to a 108! It seems to do it the most when the charger on my freedom 458 comes on initially. Is there anything in the coach system that can raise the shore power voltage that my coach instrumentation is seeing? I would think that the actual shore power would have to be varying, but perhaps it's something in the coach.  I have never seen anything like this and it's beyond my expertise, so if anyone knows more about these things I would appreciate some ideas. I tried flipping all the breakers one by one but it doesn't seem to make a difference.

Rich 2002 Magna

Re: Bizarre over-voltage on Shore power?

Reply #1 –
Yahoo Message Number: 110790
I think it has to be something in my Magna since my neighbor is plugged in to the 50 amp outlet right above mine and his coach is showing a hundred and twenty volts at the outlets inside his coach.

Re: Bizarre over-voltage on Shore power?

Reply #2 –
Yahoo Message Number: 110791
Hi, sonds like a bad nutrual wire in outside panel,a bad nutural will make the voltage change, and burn thinks up in you coach Charles 2000 magna 5886

Re: Bizarre over-voltage on Shore power? [1 Attachment]

Reply #3 –
Yahoo Message Number: 110792
Rich,

You don't say whether you're at home or in an RV Park, but....
What are the voltage readings at the source? I would check that the grounds and neutrals are in place and connections are tight.....starting at the power panel in the coach and working back to the power source (breaker panel in your home if that's where you are). Loose or lost neutrals and grounds can play strange games similar to what you are seeing.

Dave Trotter

01 Intrigue 11215

Inline image 2

Re: Bizarre over-voltage on Shore power? [1 Attachment]

Reply #4 –
Yahoo Message Number: 110797
Loose or damaged neutral lead in your cord.

Re: Bizarre over-voltage on Shore power? [1 Attachment]

Reply #5 –
Yahoo Message Number: 110816
We recently had a similar issue. Our panel for the inverter was showing a high ac fault. We were at a shop getting other things fixed so that was one more item we had to get fixed. After tracing down where the high voltage came from it turned out it was a bad transfer switch. The transfer switch in our coach is located in a cabinet in the bedroom next to the surge protector.

Re: Bizarre over-voltage on Shore power?

Reply #6 –
Yahoo Message Number: 110822
As a friend explained to me, when one leg of 50 amp goes up and the other down, suspect a bad neutral. As he said, 50 amp on the two main legs is like a teeter totter, when one leg goes up the other goes down.

Since your Progressive industries is shutting down, chase your neutral connections to the PI, including the PI connections if you get that far. I'd start at the post since that's the easiest. It could even be the plug on your 50 amp cord but I would check all the other connections before tackling the plug.

pete

2000 40' Magna CAT C-10, #5892
Pete
 2000 40'  Magna #5892  CAT C-10

Re: Bizarre over-voltage on Shore power?

Reply #7 –
Yahoo Message Number: 110824
I will do that. On my Magna, I should mention, the Progressive Industries EMS is just downstream of the transfer switch. For some reason this is how country coach wired things up in these years. I do not know why. Could a malfunctioning transfer switch cause this teeter totter overvoltage overvoltage? I have a Parallax 501

Rich 2002 Magna

Re: Bizarre over-voltage on Shore power?

Reply #8 –
Yahoo Message Number: 110825
The ems protects you from upstream, towards power source, so open neutral would down stream, toward coach.

From PI ems manual.

EMS-HW50C & EMS-HW30C

Progressive Industries understands the largest threats to a an RV's electrical system and components are surges at the power pedestal, miswired or faulty electrical power. Surges and faulty power can result in sever damages to an

Product Features:

    • Over/Under voltage Protection
    • Open Ground, Open Neutral & Reverse Polarity Detection "ยข Open Ground, Open Neutral & Reverse Polarity Protection
    • Accidental 240V Protection
    • Miswired Pedestal Indication
    • Surge Failure Indicator
    • Amperage Meter Display
    • Previous Error Code
    • A/C Frequency Protection
    • Time Delay (136 seconds)
    • Adjustable Time Delay
    • Thermally Protected

Re: Bizarre over-voltage on Shore power?

Reply #9 –
Yahoo Message Number: 110826
BTW theory behind your installation point is then it protects power coming from both powere post or generator and transfer switch failures. However it leaves transfer switch exposed.

Ray

Re: Bizarre over-voltage on Shore power?

Reply #10 –
Yahoo Message Number: 110845
On my 2000 Magan the electrical schematic shows that the EMS is after the transfer switch but in reality it is wired only for shore power and is installed before the transfer switch.

Do you see these voltages swings when on generator power? Although good power from the generator does not rule out the shore power connections in the transfer switch but would seem to rule out the output connections of the transfer switch.

pete

2000 Magna CAT-C10, #5892
Pete
 2000 40'  Magna #5892  CAT C-10