Why would my shore power suddenly start tripping?

[dralex]

NOthing has changed, there's nothing new installed and it was powering my heater and dehumidifier perfectly before the weekend. We had a fairly boistrous trip to the Dart and back and now it's tripping even with nothing plugged into the 24oV outlets. It is tripping on the boat, and also on the pontoon. Shore power is something I have not played with yet ( yes I know It's 240V, danger of death etc), but any ideas.

Thanks

 

[starboard]

Where was your extension power lead stored during that last trip. Probably has got moisture in the cable or plug, try taking the cable home and drying out for a day or so then try again.

I find most problems at our marina here are caused by damp cables.

Paul.

 

[StugeronSteve]

If it's tripping without any usage you must have some water, or a fault, in one of the connections.

 

[dralex]

Is the lead going to be the most likely culprit? I was stored in the heads locker as usual. It was a fairly damp weekend.

 

[StugeronSteve]

Yes. Although, if it is the supply lead I would have thought that the pontoon circuit breakers would flip out, but not your on-board ones. Turn off the electricity at the boat's consumer unit, plug in the lead and see whether the pontoon supply flips. If not, switch your on board supply back on and see what happens.

 

[dralex]

Thanks, will try that tomorrow evening. The sequence of events was - plug in shore power, reset both pontoon and boat circuit breakers, then turn on consumer unit and then it trips.

 

[Robin]

Alex

Damp somewhere along the line is most likely. Take the shorepower lead connectors off first and check the wiring connections inside are OK, sometimes they corrode or even come loose and pull out. Then check the socket on the boat and do the same, make sure the wires are in place and not corroded.

However, we had one that despite all connections being clean and tight still tripped with nothing running. I swapped the normal lead for our 'superlong' one and it still tripped so the boat end became prime suspect. In the end the problem was solved by replacing the on board socket and this despite taking it apart, drying it and reassembling it, so I suspect there was a damp path within the plastic itself, maybe a hairline crack like in the old days of distributor caps on cars.

Robin

 

[StugeronSteve]

Not unusual to get a compression fault where the lead has been nipped in a locker lid.

 

[dralex]

Ahhhhhhhhh

Very possible as I do tend to rest a jam a locker door on the lead. If this was the case, I would have thought there would be no power to the consumer unit to trip as the short would making a circuit before that point.

 

[Robin]

Lots of options. We have 2 trips on board, then 'our' trip on the pontoon supply box, a supply box trip that covers both berths fed from it and another trip that covers 50% of the main pontoon we are on. There seems to be no logic as to which trip trips first, you would expect the sequence to be to trip outwards from the fault but we have seen several times a visitor arriving with some kind of fault and bingo all of us are 'off' as soon as he plugs in, not just the trip on his connection broken.

 

[nedmin]

have you tried plugging into someone else temporary?or borrow their lead, RCD,s are not 100% reliable altho.they usually fail to trip.I had one that was ultra sensitive and kept tripping.I found that if I switched my consumer unit off,then plugged in the lead to the boat then switched on at boat consumer unit it was ok. Got BWB to change and no further trouble.

 

[dralex]

Thanks for the replies- I'll just start some logical fault finding- probably use another lead first and see.

Cheers

Alex

 

[savageseadog]

On a safety note, don't ignore it even if it stops tripping. Have a good look at everything.

 

[Guest]

1001 reasons ....

I have had 2 main reasons for tripping of shore power ....

a) The lead where it came across the pontoon finger joint to main pontoon trapped the lead and 'nicked' it ... Looking at the lead it appeared fine .. till you lifted it and turned it over and saw the black mark. It was a tiny nick as well - took a second look and twist of bthe cable to see it actually penetrated to the wires.
b) Simply water / damp in the plugs and sockets .... I always try to hang my plugs / sockets with ends down so that they don't get water up inside ... but its not always possible.

Pal of mine before actually had insects and spiders webs inside his fixed socket .... web literally got damp ... TRIP ! Well that's the only reason we could find ... cleaned out the web and bugs ... fine again.

 

[jimi]

d that problem, it was a damp plug. Cut the end off dried and rewired it.

 

[DaveS]

If I understand correctly your circuit breaker (RCD?) is wired between the boat inlet and the consumer unit. With the consumer unit main switch off both your circuit breaker and the pontoon supply one stay in. On closing the consumer unit main switch one or both circuit breaker trips.

If the above description is correct then, barring fortuitous coincidences, I'd expect to find the problem downstream of the consumer unit mainswitch. Have you tried closing the mainswitch with the final circuit MCBs open? If this causes a trip, I'd suspect damp or adrift wiring in the consumer unit. If the breakers hold in then the problem is in a final circuit, and closing the individual MCBs in turn should determine which.