Electrics Conundrum

[stranded]

A fantastic weekend's sail from Lymington down to Chichester yesterday, and back this morning, marred only by that feeling I am going to have to hand a blank check to the yard next week. unless...!

Got to the boat on Friday night to find no shore power. A bit of investigation revealed that the socket where the little dongly meter is joined into our shore power lead had burnt out. Marina very helpfully supplied a replacement which delivers current up to the RCD where it comes onto the boat, but we are not getting any power distributed on board. I still don't really understand electrics but I am trying. Anyway, I have been unable to find any more fuses or swithes between the RCD where the lead comes on board and a Sterling digital AC automatic crossover switch which does not detect any shore power (nor does show a fault). Except... when I switch the generator on, after a few seconds the shorepower LED on the Sterling device comes on, goes steady and the generator light flashes, which as I understand it means that shorepower is present and the crossover has switched to that in preference to the generator. Of course when I turn the generator off, the shorepower 'disappears' again. An additional symptom, which may I suppose be entirely a coincidence, is that the batteries are no longer being charged by the engine when it is running. I have tripped and flipped every switch and RCD I can find to no effect but am reluctant to play with what I don't understand as electricity scares me, especially on a boat - my mum always told me electrickery and water don't mix. Anyway, before I make the fateful call to the yard tomorrow, is there some obvious explanation for this, to me slightly odd, set of circumstances? If its any use as well as the Sterling thing there is an electronic alternator regulator and a Mastervolt battery charger on board - the latter seems to charge when the generator is running but is otherwise dead as a dodo (don't know whether it is supposed to when the alternator is doing the work - guess not).

Any clues?

Mark

 

[LadyInBed]

I would suspect the Sterling digital AC automatic crossover switch, but it does sound that you might be over the limit of your ability to isolate it out.
I hope I don't sound patronising.

 

[stranded]

I was at the limit of my ability when I flipped the RCD switch! But yes, looks like another one for the yard.

 

[nigelmercier]

The fact that a component has burnt out means that there is a fault somewhere that isn't going to be fixed by flipping switches. A knowledgable mate with a meter would be handy!

 

[stranded]

Indeed. The marina guys reckon that the burnout was caused by water in the socket at the shore end so I am hoping that whatever has happened is a consequence of that, rather than the burnout being a consequence of something wrong on the boat. Not that it makes much difference I suppose. Anyway, I've asked the yard to investigate. And I've gotten myself a multi-meter now so one I have digested the relevant bits of the manual I should hopefully be in a better position to work through the system and at least figure out where things stop working, even if I still can't fix it.

 

[savageseadog]

Some marinco power connectors burn out regularly, I don't know if that's what you've got. You should replace both the plug and the socket, both connectors and wiring, it will be burnt. Dob't bother metering about till you've done that.

 

[stranded]

Yes, that's been done. It's how it could be that the Sterling Crossover can only 'see' (and switch to) the shore power when the generator is running that is perplexing me. As I said, I've got the yard on it now, so it is more an intellectual than a practical challenge.