Oh Joy, another electric problem

This is where to measure your receptacle that the RV 50AMP plug goes into at the house.



Be carefull here with your meter probes as there is 240VAC available here between the two HOT sockets...

Roy Ken

It might be the house breaker itself. I had one go bad on a water heater (household) and got to changing everything...finally decided to change breakers.....never had another problem

Agree with our(OP's) diagnosis. If everything works on generator, but not real 50 amp shore power, you have a problem in the shore power cord or ATS.

But, start by verifying that you do have real 50 amp service at the outlet.

IF YOU ARE SAFE WORKING AROUND 120/240 VAC POWER:

Outer straights= hots.
Center straight= neutral.
Center round= ground.

So, either outer straight to either center straight or round= 120 VAC
Center round to center straight= 0
Outer straight to outer straight= 240 VAC

Next, check male end of shore power cord for overheating. If shore power cord is not hard wired, use ohm meter to check that continuity through the shore power cord.

If the outlet and shore power cord checks out (or shore power cord hard wired on coach end), turn off inverter, generator off, shore power disconnected: Open ATS (Automatic Transfer Switch) and check there.

Artum Snowbird wrote:
If it worked just fine for a couple of hours, then tripped out in the house, it could be because you have really reached the limit of the breaker. I wonder if they have Christmas lights and displays on the same circuit somehow?

Or are you plugged into the same circuit as the stove, oven, or hot water tank? Maybe even a hot tub perhaps?

x2, also in your post you said there was a 40A fuse, 50A service in your RV if maxed out would blow a 40A fuse. You mentioned possibly your power cord, with it disconnected does the fuse/breaker still trip? JMT

With just extension cord plugged in does their breaker trip or stay ON?
Are you turning your RV MAIN breaker OFF (not just the individual circuit breakers) when trying to use your power cord and extension cord?

If the house breaker doesn't trip with just extension cord plugged in and does trip when you plug into your power cord (With the MAIN Breaker OFF in RV)
then it does point to your power cord being problem.

Check the plug on your power cord......burnt/scorched prongs.
If your cord is hardwired check connections for loose/bad connections
Also check connections at transfer switch (OK power from gen...but not shore power)

IF your cord unplugs from RV.check receptacle on RV and the plug on that end of cord....loose/burnt connections

You could do a continuity check on each leg in cord
Cut off plug on cord and replace
Replace the whole cord

And WHY is a 50A circuit being feed from a 40A breaker.......wrong size wire?

If it worked just fine for a couple of hours, then tripped out in the house, it could be because you have really reached the limit of the breaker. I wonder if they have Christmas lights and displays on the same circuit somehow?

Or are you plugged into the same circuit as the stove, oven, or hot water tank? Maybe even a hot tub perhaps?