AC Panel Master Breaker insta-flips

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Hi all,

Just got back from a cruise and now the master ON switch for my AC Panel instantly flips closed. All the subsequent breakers, charger, outlets, and water heater, are all OFF. I have a Smart Plug and checked the wire connections on the socket and they seem fine. I tried a resistance test with the multimeter of the socket side of the shore power cable but found nothing conclusive. Admittedly, I don't know what I'm doing with the multimeter here.

Pulling the panel off was also inconclusive, as the connections look original and not in terrible shape. The shore power worked fine at the marina we stayed at last night. Somewhere in the 5 hour motor home, something died or changed. My first instinct was water getting in the shore power cord, but it's been sitting in the sun with the same issues.

Any thoughts as to what could be causing the short? Perhaps the breaker itself is old and dead?
 

1911tex

Sustaining Member
Happened to me last week. Marina blamed my boat circuit or my shore power cord for the problem. Turns out the master fuse panel (30amps per slip) on the marina dock had a few old defective switches including the one for my slip. Marina replaced my slips 30amp fuse and I no longer have the problem.
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
I did try my neighbor's shore power post as well and the same issue is occurring. Not sure if that rules out the marina or not, but I will definitely send them an email.
 

GrandpaSteve

Sustaining Member
If it works for them there must be a problem on your boat. It is still worthwhile to enlist their help.
 
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1911tex

Sustaining Member
Backup cure: Check your shore power plugs on both the dock end and your boat....check for corrosion on the terminals.
 

Dave G.

1984 EY30+ Ludington, MI
Is there a breaker on the Marina side of your shore power cable and if so is it tripping too ? If not I would think the problem lies on the boat supply side of your AC panel. It seems to me if it were your cable or connectors the marina breaker would trip too.
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
The breaker on the shore power pedestal is not flipping, just my master switch. Maybe the breaker itself is dying... I'll try my buddy's shore power cable today and then try swapping the breaker itself out. Anyone know if the master breaker on the 32-3 is a 30A switch?
 

Dave G.

1984 EY30+ Ludington, MI
AC will jump a short distance and short so make sure you have good clearance between all the neutral and hots on the switches and connectors. Since you had all the other breakers off it has to be between the main and supply to individual circuits or as you said the main breaker itself. There is a possibility there is a dead short in one of the individual circuit breakers too. You could isolate that by removing the hot wires to the individual circuits and then see if the main trips when you power up. If it does than probably the main itself. If it doesn't then hook up one circuit at a time until you find the one that trips it.
 
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