Shore power 1 causing shore power 2 breaker to trip

[SaltyCracker]

I have a 1995 Carver 325 aft cabin. Shore power 2 runs my 2 AC units and the pump. With both AC's running they draw about 22 amps and are trouble free. However, when there is a significant load put on shore power 1 (microwave, water heater, toaster etc.) this often causes the shore power 2 main breaker to trip.

When this happens the load on shore power 1 is not what I would consider to be excessive, typically pulling around 15 amps.

Any suggestions of what may be causing this or where to start troubleshooting would be greatly appreciated.

[bud37]

Welcome to the forum......Just a quick idea.....have the marina electrician check your dock pedestal first, there may be some funky wiring there.

[Tireless]

Are you running one shore cable with a "Y" at the boat, or are you using two separate cables?

Greg

[km1125]

Do both your shore power cables have clean ends (the connections)? Whether the source is a 240 circuit that's shared by two 120 circuits or two separate 120 circuits that share a common neutral, a big load on one side will affect the voltage available on the other side. When the voltage drops to the A/C compressors, the current goes up and could easily exceed the rating on the breaker.

Do you have voltmeters for each incoming line? What do those show when you're running the house loads?

[chpsk8]

Most likely it's common neutrals in the panel.
Shore 1 and 2 are probably sharing the same neutral bus bar and need to be isolated.

Our marina did an electrical upgrade and half the boats needed to have their neutrals separated. It was common practice in the past to share, but with the way they are required to wire docks now, this can cause problems.

[SaltyCracker]

Thanks for the advice, I will look into these suggestions.

The pedestals at the marina have one 30 amp outlet and one 50 amp outlet. Shore power one is running off the 30 amp. Shore power 2 runs off the 50 amp and has a 50-30 amp adapter. I recently replaced the cables and inlets and inspect the cables regularly. The look good.