Electrical issue - Mine or Theirs?

Old Mustanger · 03-20-2024, 08:19 AM

Got to our final destination yesterday afternoon (after 3 days/2 nights on the road with no problems), setting up DW announced that she couldn't set the clock on the microwave! Checking I found that we had no power to any receptacles except those on the GFCI circuit. Was getting prepared to track down a loose connection, but went to check the EMS first, it was indicating that L1 had 124V, 0A, L2 125V 5A. Checked the upper AC by trying to turn on fan only and no power to it.
I switched to 30A hookup (with adapter) and everything has power, it's too cold for using the heat pump so no problem running on 30A.
If this is my problem would hooking thru the adapter tie both lines together so that it bypasses the problem, or do they have a bad breaker at the power pole?

wiredgeorge · 03-20-2024, 08:29 AM

Quote:

Originally Posted by Old Mustanger

Got to our final destination yesterday afternoon (after 3 days/2 nights on the road with no problems), setting up DW announced that she couldn't set the clock on the microwave! Checking I found that we had no power to any receptacles except those on the GFCI circuit. Was getting prepared to track down a loose connection, but went to check the EMS first, it was indicating that L1 had 124V, 0A, L2 125V 5A. Checked the upper AC by trying to turn on fan only and no power to it.
I switched to 30A hookup (with adapter) and everything has power, it's too cold for using the heat pump so no problem running on 30A.
If this is my problem would hooking thru the adapter tie both lines together so that it bypasses the problem, or do they have a bad breaker at the power pole?

If your EMS shows 124V on both legs but no draw on L1, suspect you need to check the wiring at your power center that connects the one hot leg to the breaker(s) it energizes.

NH_Bulldog · 03-20-2024, 08:55 AM

Is your EMS a plug-in type or hardwired?

The EMS appears to be sensing power to both legs, but only one leg has any load. Besides what George suggested, I would also try flipping the main 50a breaker off and then back on, and maybe cycling all the other breakers as well while you are at it. It could very well have tripped one leg of the main breaker.

However, I do think it's odd that when running the 30a power, all the outlets suddenly work. Typically a 50a load center is set up to power two different sets of loads, one for each leg. Since a 30a source is only one leg, something isn't adding up. This leads me back to my original question; plug in or hardwired, and can you try it out at another pedestal?

**sourdough** · 03-20-2024, 09:07 AM

How are you set up? EMS at ped then the power cable or power cable to EMS (hardwired) then into trailer? If the EMS is showing power on both legs coming in sounds like you are possibly losing one leg of it past the EMS. The suggestions on cycling the breakers is good and you can use a VOM to start running down where the loss is - maybe a bad plug/receptacle/connection past where the EMS is being fed power?

Old Mustanger · 03-20-2024, 01:04 PM

Thanks for the responsive and questions.
EMS is plug in, 50A setup was 50A EMS to power cord, to trailer receptacle Current setup is 30A EMS to adapter to power cord to trailer.
I have already cycled all breakers, including the 2 pole main.
I won't be able to check at another power pole until next week when we head back home.

**sourdough** · 03-20-2024, 01:35 PM

Where are you putting the dogbone that makes the 30A work? The dogbone takes one hot lead then splits it to feed both hot legs going into the trailer. Wherever you put the dogbone is in front of the loss of power OR a defective component is being removed from the circuit.

Old Mustanger · 03-20-2024, 05:07 PM

Quote:

Originally Posted by sourdough

Where are you putting the dogbone that makes the 30A work? The dogbone takes one hot lead then splits it to feed both hot legs going into the trailer. Wherever you put the dogbone is in front of the loss of power OR a defective component is being removed from the circuit.

The dog bone is connected to the 30A EMS, which is plugged into the pedestal, then my power cord is plugged into the dog bone. So the sequence is:
1. Power pedestal
2. EMS
3.30 to 50 dog bone
4. 50A power cord
5. Trailer

So if I'm understanding what you are saying it seems as if the dog bone has removed a defective source from the equation, that is a bad 50A breaker?

**sourdough** · 03-20-2024, 07:54 PM

Sleepy time but; are you saying when you went to the 30A hookup you removed all the connections at the ped and went with a 30A EMS then a 30A to 50A dogbone?

With the 50A EMS you show voltage on both legs. With the 30A EMS....what is it plugged into - the 30A plug vs the 50A at the ped? If you're moving the power feed from the 30A to 50A receptacle in the ped is something that needs to be articulated. All previous comments sounded like you were trying to power from the 50A plug and then use adapters. If you are moving cables and using different EMS units in different receptacles that makes a huge difference. You may have lost one leg of the 50A at the ped plug which you can determine in a couple of minutes with a VOM.

GlasNav · 03-21-2024, 04:53 AM

???? What does the 50 AMP Breaker in the pedestal have to do with this situation when the EMS is plugged into the 30 outlet of the pedestal????

This is the sequence I understand that Old Mustanger described.

30AMP socket of Pedestal
30AMP EMS
30 to 50 Dogbone
50 Shorepower cord
Trailer

Old Mustanger · 03-21-2024, 06:22 AM

Originally I had a 50A EMS plugged into the 50A receptacle on the pad. Now I have the 30A EMS plugged into the 30A receptacle on the pad, then the 30 to 50 dog bone.
I'm starting to wonder if my 9 year old 50A EMS has gone bad, I am going to put it after the dog bone and see what I get later today
This campground is picky about messing with their equipment so I don't want to take the power station apart to test their breaker so I will let them do it once I determine for sure that it is not my problem.

**sourdough** · 03-21-2024, 06:25 AM

Quote:

Originally Posted by Old Mustanger

Originally I had a 50A EMS plugged into the 50A receptacle on the pad. Now I have the 30A EMS plugged into the 30A receptacle on the pad, then the 30 to 50 dog bone.
I'm starting to wonder if my 9 year old 50A EMS has gone bad, I am going to put it after the dog bone and see what I get later today
This campground is picky about messing with their equipment so I don't want to take the power station apart to test their breaker so I will let them do it once I determine for sure that it is not my problem.

Leave the EMS plugged into the 50A plug with the trailer power cable disconnected. Use a VOM in the end of the EMS cable where the trailer cable plugs in and check for your voltages there - you may have lost one leg.

**sourdough** · 03-21-2024, 06:28 AM

Quote:

Originally Posted by GlasNav

???? What does the 50 AMP Breaker in the pedestal have to do with this situation when the EMS is plugged into the 30 outlet of the pedestal????

This is the sequence I understand that Old Mustanger described.

30AMP socket of Pedestal
30AMP EMS
30 to 50 Dogbone
50 Shorepower cord
Trailer

That is what I was asking OP. Obviously if connected as you describe the 50A receptacle isn't in the picture. If connected like he said he was originally it does come into play. He has clarified.

GlasNav · 03-21-2024, 06:30 AM

Quote:

Originally Posted by sourdough

Leave the EMS plugged into the 50A plug with the trailer power cable disconnected. Use a VOM in the end of the EMS cable where the trailer cable plugs in and check for your voltages there - you may have lost one leg.

Agreed... Something has lost a leg, either the 50 AMP pedestal socket or one of the modules in the EMS has failed. My hunch is a loose connection in the pedestal.

NH_Bulldog · 03-21-2024, 06:33 AM

My thought on this given the information we have.

On 50a, half the panel is dead and this is supported by the EMS saying that it senses power on both legs, but load on only one leg.

When you switch to 30a, both sides of the panel work.

This tells me that the RV is fine, and the 50a cord from the RV is fine since they remain unchanged in the equation.

We know the RV cord is good, and we know that the pedestal is pushing power on both legs, so what remains is the EMS as the culprit. In VERY basic terms, the EMS receives power on one side of a switch, and if it gets the all-clear, it sends power through the switch and out to the RV. We know that we have appropriate power on the supply side of the switch, but the sensors on the load side of the switch are only getting a reading on one leg. This tells me that your EMS has failed.

If you feel comfortable with the pedestal power setup, the easiest way to confirm this is to simply eliminate the EMS from the equation and plug directly into the 50a pedestal and then check your circuits for operation. My guess based on information presented is that everything will work fine. This does not mean that I support not using the EMS (I would continue with the 30a EMS until you can get a new 50a).

GlasNav · 03-21-2024, 06:35 AM

Old Mustanger: When the campground maintenance person comes over, make sure they simply don't use a VOM and say all is good. Needs to be opened up and inspected, unless they have a dummy load box to confirm their service supply at the pedestals. Can have voltage, but without amperage you get zilch.

**sourdough** · 03-21-2024, 06:36 AM

Quote:

Originally Posted by GlasNav

Agreed... Something has lost a leg, either the 50 AMP pedestal socket or one of the modules in the EMS has failed. My hunch is a loose connection in the pedestal.

I think it's probably the ped as well. Not knowing the condition of the park/ped/electrical system it's hard to guess but don't see too many EMS units go bad on one side "because". OP depending on what's easiest you can just unplug everything from the ped then read the pins on the ped receptacle for power. You will know which way to look from that.

Don77 · 03-21-2024, 06:45 AM

Quote:

Originally Posted by sourdough

Leave the EMS plugged into the 50A plug with the trailer power cable disconnected. Use a VOM in the end of the EMS cable where the trailer cable plugs in and check for your voltages there - you may have lost one leg.

I have a cheap VOM I keep in my RV to ck peds at parks for that same reason,
I have been at rv parks that had bad 30 and 20 amp outlets!
Its a cheap Harbor Freight meter that if I lone it to someone and don't get it back I m not out a lot of money and can get it replaced on the cheap.

Don

GlasNav · 03-21-2024, 06:52 AM

Old Mustanger, I just looked at your profile. Something tells me you are enjoying all the opinions and recommendations considering your knowledge and background!

Remember to bite your lip and be quiet when the campground person tries to tell you a bunch of bull****.

rhagfo · 03-21-2024, 05:49 PM

Quote:

Originally Posted by sourdough

Leave the EMS plugged into the 50A plug with the trailer power cable disconnected. Use a VOM in the end of the EMS cable where the trailer cable plugs in and check for your voltages there - you may have lost one leg.

I agree, sounds like a bad EMS, as it reads power on both legs, but seems to only deliver on one side down line.

Old Mustanger · 03-22-2024, 05:47 PM

OK y'all, thanks again for all of your responses and suggestion, sorry I didn't follow up quicker. It comes down to either the breaker or receptacle on the pedestal.
I'm going to stay with the hookup I have now thru the 30A power supply. The campground personnel are super busy and they asked if I could live with it until Monday.

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