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electrical problem 1 leg dead and only showing 30 amps

Yahoo Message Number: 112687
Hi There: We are plugged in a 50 amp plug but can not change our input past 30 amps. It is showing volts to both legs but only one leg appears to be drawing power.
As we use the air conditions, we tend to be drawing to much power and keep popping the circuit breaker.
We are also hearing a loud thump from the inverter when it seems to be drawing excess power.
We have had the pedestal checked and the power from there is fine.
Any ideas?
Thanks,

Laura Lewis
Magna '08
6459
Palm springs area now.

Re: electrical problem re: 1 leg dead and only showing 30 amps

Reply #1
Yahoo Message Number: 112689
Laura,

I had a bad connection in my cable once that caused the amp drop. So, I'd suggest you check the ends of your power cables
Steve
Magna 5220


Re: electrical problem re: 1 leg dead and only showing 30 amps

Reply #2
Yahoo Message Number: 112697
If you measure the voltage on both legs at pedestal and its ok, then at breaker panel inside the coach and it missing a leg Its your cable. If it is ok at the breaker

Panel inside the coach  then it either the transfer switch and or inverter charger. If the two legs have a large voltage difference then you have a open neutral some place ( if  one leg is not 0 volts) Be sure to check the breakers on the inverter. And the main breakers in the power panel.

Marv Intrigue 11314

: Country-Coach-Owners@yahoogroups.com [mailto:Country-Coach-Owners@yahoogroups.com]
Sent: Monday, October 09, 2017 10:59 AM
To: Country-Coach-Owners@yahoogroups.com
Subject: [Country-Coach-Owners] electrical problem re: 1 leg dead and only showing 30 amps

Hi There: We are plugged in a 50 amp plug but cannot change our input past 30 amps. It is showing volts to both legs but only one leg appears to be drawing power.
As we use the air conditions, we tend to be drawing to much power and keep popping the circuit breaker.
We are also hearing a loud thump from the inverter when it seems to be drawing excess power.
We have had the pedestal checked and the power from there is fine.
Any ideas?
Thanks,

Laura Lewis
Magna '08
6459
Palm springs area now.



Re: electrical problem re: 1 leg dead and only showing 30 amps

Reply #4
Yahoo Message Number: 112709
If you have two phase 210-250VAC between the two legs, it has no bearing on the "amps" of service. You must look at the breakers to determine the amps available at the plug.

A 2 phase breaker will have 2 breakers in the box, typically bound together so that they both flip on/off always together. If the are not bound, you could have one off and one on, resulting in one phase (110-125VAC).

The thump is your voltage switch box, it looks for input voltage from multiple sources, and connects after a time period to one of them. It prevents you from having two sources coming into your RV box at the same time. So if your generator is running and currently providing power, if you then also plug into shore power, that could be really dangerous if they both were connected at the same time. So, you could say it isolates your input power to one source.

The 30amp RV service is single phase, which is connected to both sides of your breaker box, where two phase will be one phase for each side. Same for 15-20 amp service, one phase.

On the inverter panel, mine does show a "> 30" input option, but it only lets me select 30, 20, 15 or 5 amp options. So the > 30 is there, but not selectable. I assume this has to do with the size of my inverter which is used to synch up the phase of the RV DC->AC converter, generator, etc, and when it goes thump and connects to another power source.

For SURE your panel has NO IDEA what the source amperage rating is. It might seem like perhaps it would assume 2 phase is 50amp, but if it was that smart, then it would not need us (the humans) to select the correct amp input. You must always select the correct amp input rating.

A reading of 210-250VAC at the meter/plug does not mean everything is good. That does not tell you the load capacity of the plug/wire, etc.
Where I'm at now, one phase of my power has a bad connection in the meter box, and so if I put a load on that phase, the voltage will drop due to resistance in the bad connection, and my switch box detects the "bad" voltage level, and so "thump" and it disconnects both phases.
But, my box will disconnect both phases vs. just the bad one.

If you have only one phase of power, 110-125VAC, then your switch box will automatically connect that one phase to BOTH sides of your breaker box, you will have power to everything.

If you have power to only one side of your breaker box, then check your inverter for a popped circuit.

You will not be able to test your current amperage use - your inverter panel shows DC amps, it does not show your A/C amp usage. You cannot test amps unless your meter is in-line on the power, meaning, all power going through that meter in series (unlike testing voltage which can be in parallel) - something that is usually only done at low amps. I think there are some clamp-over the cable amp meters, but they are not going to be very accurate.

Wes
Currently in Mexico
Wes Owens
2000 CC Allure 36' #30443
Full time, western US summer, Mexico 6 months over winter.

Re: electrical problem re: 1 leg dead and only showing 30 amps

Reply #5
Yahoo Message Number: 112711
Can you borrow a Power Pal to check the pedestal? Sounds like it is miswired. Or as others have suggested you need to measure volts between the two hot wires and see 240 volts. Pedestals can be miswired to show 120 volts on both legs, but that is all you have, 120v, 30 amps.

Greg
06 Magna

2006 Magna Rembrandt C13
2016 Jeep GC toad