400: Fixing Stray Currents

[b_rodwell]

I can't completely turn off these lights - main cabin, cockpit and starboard cabin on my Lagoon 400. When I turn the switch off, the lights just go dim rather than off. I can only get them completely off by turning off the master cabin light switch on the control panel.

I had a marine electrician work on this and he found some faulty wires. When he finished I had no lights that would not turn off. Then I went sailing and the problem (some lights not turning off) reappeared. At the moment I handle this by turning the master light switch off most of the time. This is a little inconvenient. This problem has appeared and then gone away with no intervention from me. It goes away after a period of not sailing.

I also had a serious problem with my saildrive anodes being totally consumed. I suspect this is related to the stray current problem.

I don't want to keep engaging marine electricians and particularly for a problem that reappears. I presume my problem is caused by faulty wiring. Could someone advise me of the steps to diagnose which cables are faulty? Are there other things I should be checking? I have a multimeter.

Thanks

Brian

[CatNewBee]

With a multimeter you can track down the wires until you find the source.
What kind of lights are you referring to? (LED or bulbs?)

I have some LED stripes, that do continue to emit some glowing light for a long time even after pulling the plug - this is due to very little consumption and some capacitors along the chain that usually regulate the voltage and some half-dead LED's.

Another source in regular circuits may be ground connection problems due to oxidation, so you end up with a ghost circuit over more than one regular loop, this is really hard to find.

I would take the circuit diagram and track down the wires and plugs along the line, open the circuit at some points and see what happens.

[b_rodwell]

All the lights are LEDs.

I didn't get a circuit diagram with my (new) Lagoon 400 S2. Lagoon does not supply that.

I have started the process of following the offending circuits and measuring the voltages. Still WIP. It is very slow work.

Thanks

Brian