Lost leg on 50 amp service

[newyorkRVr]

I was in Georgia when a storm went thru. Now when I plug into a 50 amp service, the control center only recognizes 30 amps. We checked the park power and it was all there. Tried 2 other campgrounds, still only 30 amps. Is there an in-line fuse somewhere or is the control center damaged? Any assistance will be greatly appreciated.

[richard5933]

If you are comfortable working with electric connections, unplug your coach, turn off the generator, and then check all the connections inside your transfer switch. Might be a good idea to also check the connections all the way from the inlet to the breaker panel, as well as the power cord itself. My guess is that you'll find a loose connection in there, and hopefully it hasn't yet burned up the insulation and done any damage.

[Howard Burger]

What I'm seeing in your post is this: you have a 50 amp service for your unit. This means you have a male plug with four prongs: two hots, a neutral and a ground. A 2-pole 50 amp breaker controls power into the female receptacle you plug into at the pedestal. Each one of the hots is called a 'leg'.



It sounds like you now plug into a pedestal and only one 'leg' is hot in the panel in you unit. Right?



It's still a 50 amp 'leg', which means if you exceed 50 amps the breaker will trip.


The 30 amp service is only three prongs, one hot, one neutral and one ground and has a single pole 30 amp breaker.


Now,I assume you checked the pedestal with a dmm or voltage tester and found both legs are hot, right?


Now here's the tricky part. If you're not trained in electrical work, don't pull the panel cover and check your panel to see if both legs are hot. Do this: find a 240V receptacle and use the dmm or voltage tester to check both legs. One hot, one not? If you don't have a 240 V receptacle (in a house it would be for the electric range or electric dryer; I don't know what would need a 240V rec. in a class A), get someone who does electrical work to check you panel.


Now you can start troubleshooting.

[Switchflicke]

Originally Posted by newyorkRVr

I was in Georgia when a storm went thru. Now when I plug into a 50 amp service, the control center only recognizes 30 amps. We checked the park power and it was all there. Tried 2 other campgrounds, still only 30 amps. Is there an in-line fuse somewhere or is the control center damaged? Any assistance will be greatly appreciated.

If all your plugs and stuff works, then I think you have 50 amps when plugged into a 4 prong 50 amp service outlet.
If the control center 'thinks' you have only 30 amps, there is a fault with the control center. On my rig, when the electric water heater circuit breaker is OFF, the control center 'thinks' we are connected to 30 amp irregardless of the fact that we are plugged into 50 amp. I guess the control center uses that particular circuit to help determine 50 amps.
There is also a fuse on the electronic board of the control center right close to the main circuit breaker panel. Might be blowed messing up the control logic.

Make sure to let us know how you make out.


Stan
The electronic board is within the main circuit breaker panel

[Spk64]

Verify all your breakers are turned on in your breaker panel in the coach. The sensing circuit may be tied to a breaker that was turned off or tripped.

[bad1032]

just went through this,i losy a leg on the shore power and a leg on generator, I had to use both to get it all to work. It wa the automatic transfer switch, have it tested. that's where your issue is

[John Hilley]

Probably as Switchflicke says, it is the breaker for the water heater. Switch the water heater off and on a couple of times. I would do it with the shore cord unplugged or the pedestal breakers off.

[KanzKran]

Originally Posted by Spk64

Verify all your breakers are turned on in your breaker panel in the coach. The sensing circuit may be tied to a breaker that was turned off or tripped.

I would just add that the OP should cycle the breakers, fully 'off' then back to 'on', not just visually check. Many breakers don't show tripped status very well, and some even feel like they're still on when they're not (free-trip handles). I get calls every couple of years from DW's sister with exactly that issue. Fortunately, no site visit required for that.

[Ndrorder]

The only way the control center could assume 30A service is if one leg of the power cord were dead or the voltage between legs is 0.


Any chance a 30A to 50A dog bone adapter is connected. 50A 240VAC at the pole provides 50A to each hot leg.



If 50A service is identified when the generator is running, it would limit the issue to be from the transfer switch to the plug on the land line.


If the generator doesn't provide 50A service, problem is with the transfer switch toward coach.

[John Hilley]

The CT (current transformer) is in the water heater circuit. It helps determine whether 30 amp or 50 amp

[twinboat]

The control center decides if you have 30 amp or 50 amp service by measuring voltage between L 1 and L 2.

If it measures 0 volts, it assumes 30 amp service. If it measures 240 volts, it assumes 50 amp service.

If one of the sense lines is tied to a breaker that is off, it will measure 0 volts and assume 30 amp service.

[Mr_D]

Originally Posted by AK_Howard

What I'm seeing in your post is this: you have a 50 amp service for your unit. This means you have a male plug with four prongs: two hots, a neutral and a ground. A 2-pole 50 amp breaker controls power into the female receptacle you plug into at the pedestal. Each one of the hots is called a 'leg'.

It sounds like you now plug into a pedestal and only one 'leg' is hot in the panel in you unit. Right?

It's still a 50 amp 'leg', which means if you exceed 50 amps the breaker will trip.

The 30 amp service is only three prongs, one hot, one neutral and one ground and has a single pole 30 amp breaker.

Now,I assume you checked the pedestal with a dmm or voltage tester and found both legs are hot, right?

Now here's the tricky part. If you're not trained in electrical work, don't pull the panel cover and check your panel to see if both legs are hot. Do this: find a 240V receptacle and use the dmm or voltage tester to check both legs. One hot, one not? If you don't have a 240 V receptacle (in a house it would be for the electric range or electric dryer; I don't know what would need a 240V rec. in a class A), get someone who does electrical work to check you panel.

Now you can start troubleshooting.

Some of the higher end RV's like mine do have a 240 volt dryer and even fewer have a 240 volt range.

[bruceisla]

So .... what happens when you use the generator?

[twinboat]

Originally Posted by bruceisla

So .... what happens when you use the generator?

If your asking about Mr.D, he has a 240 volt generator.