Shore power trips breaker 2 cords

[Luhrs40]

I have a panel that supports 2 30 amp cords. At marina only have access to one 30 amp twist lock outlet and one 20 amp outlet have 2 cords plugged in one with pigtail adapter (about 1 foot long) when I set panel to 1 line and turn on battery charger no problem when I set panel to 2 lines it trips breaker on boat panel tried reversing cords at dock swapped pigtail and still did the same thing. Any advice welcome

 

[Bondo]

At marina only have access to one 30 amp twist lock outlet and one 20 amp outlet have 2 cords plugged in one with pigtail adapter (about 1 foot long) when I set panel to 1 line and turn on battery charger no problem when I set panel to 2 lines it trips breaker on boat panel

Ayuh,.... Welcome Aboard,.... Just a guess, but I'm thinkin' both yer power cords are run from the same leg of the shore panel, when ya combine 'em, it's a dead short,....

 

[alldodge]

It could be your panel is picking up a ground fault. Are you using 3 prong plug on 20 amp outlet?

 

[Grandad]

If your system has a common neutral connection between the two power supplies, a very small imbalance in neutral current to line current (.005 amp) could cause a GFCI to just do its job and trip as designed. - Grandad