Electrical problem any ideas please!

[zimmer4me]

I have an electrical prob which I need to look at but dont know where to start.

Firstly our boat is all 12v and there is a problem with the plug sockets which seems to have arisen since we had a new relay fitted as emergency whilst out cruising. This I think might be where the problem is.

After I turn on the battery isolater switch none of the 12v lights or sockets etc work until I plug in my tv ariel booster. This appears to complete a circuit so I suspect that the co-ax cable is earthing or whatever the correct term is and that cannot be right nor safe.

As I do not know much about wiring and relays etc can anyone suggest what I could try to resolve it.

It would be nice to sort it without calling out an electrician.

In the mean time I always turn off everything when leaving the boat as we are not live aboards.

tks

 

JK

[bottle]

Dear JK

 

If you are still near the place where the relay was fitted ask them to check it as the problem was not there before.

 

Alternatively I would look at the relay to see if there are any loose connections or wires not connected at all.

 

After that my "expertise" runs out but there must be some one who may help you further.

 

good luck

[PhilipL]

Not sure if we're going to be able to help with this one, but what was the relay for, and did replace an existing one?

 

Phil

[NB Willawaw]

The aerial booster is obviously completing a circuit somewhere. On the face of it, the connection with the relay being replaced is not obvious.

This will be a hard one to sort out at distance and its probably something simple.

Its really annoying to get an electrician onboard only to see him fix it in two minutes, especially if he charges you a call-out.

Do you have a circuit diagram for the boat ?

I would be tempted to try to trace the circuit round with a meter or a 12V bulb connected to two croc clips to try to see where the 12V disappears in the circuit.

 

Echoing a previous reader, what does the relay do ?

Is the boat wired as a negative earth ? i.e are you using the hull of the boat as a negative wire ?

[John Orentas]

You have an earth fault one way or another. You are nodoubt right in saying that the negative supply to all your sockets is being fed in some way from your TV aerial.

 

I assume the relay you refer to, is the split-charge relay. It is likely that changing is it was a coincidence or somehow something was dislodged or damaged at the time.

 

The first thing to check is the isolator switch. It is common for the main isolator to switch the negative supply from the batteries, is it turned on? if it is on, is it faulty, short it out, does that restore the supply.

 

If not, you now require a multi-meter, or a lamp with two wires connected.

 

First check that all the neg or - side of the batteries are connected together with conductors going to the engine, appliances and whatever sockets are installed. You will also find it is electrically connected to the metallic shell of the boat.

 

Work out-wards away from the batteries with one side of the meter or lamp connected to the pos. or + side of the batteries, you should find a 12 volt reading on all the neg. connections, all the way out to your sockets.

 

Wherever you fail to get 12 volts, that is the area of the fault.

 

Let us know how you get on.

[zimmer4me]

Thanks for all the replies.. yes its a split relay for charging but I know nothing of it other than that...

When I next get down the boat I will try your suggestions.

Looks like might be this weekend as I will be crusing her to dry dock for blacking and the guy doing it might also have time to look at it as well.

Hope you are not all snow bound !

cheers all

JK

[DHutch]

So im guessing you dont have a wiring diagram of the boat?

[zimmer4me]

So im guessing you dont have a wiring diagram of the boat?

<{POST_SNAPBACK}>

You are correct I bought her second hand and am still getting to know all the little foibles and "features" left behind.

tks anyway

JK