Why can't I turn off my electrics? (photo shown)

[rob2]

Hidden wiring behind headlinings or disappearing through bulkheads may seem impossible to sort out, but in the first instance may not need to be tracked too thoroughly (although long-term it would be a good idea to learn where it all goes). At first, you should be able to simply find out which sections of wiring are live with the swiches on or off by using a multimeter or test bulb to each connection from the battery negatives. I must say I'm surprised that the secondary isolation switch doesn't kill the permanent feeds. I have one or two items fed from the "wrong" side of the selector switch, so that it is always live, but there is such a secondary switch to allow them to be switched off in case of a fault, after all a short could set light to the boat!

Rob.

 

[sarabande]

MM has made a very good point.

It is also probably worth considering what might happen if a spanner or kitchen knife dropped on those exposed terminals. Some plastic insulating covers might be a good safety investment.

Best of luck with the drawings, It really is quite easy, if a little tedious, but you will benefit greatly from the knowledge.

 

[nigelmercier]

A sheet of paper and a pencil. Draw a couple of rectangles to represent the batteries, and circles or smaller rectangles to represent other items. Draw on where each bit of spaghetti goes.

This is the proper way to proceed. Some tips:

You may need to tape several pieces of paper together, don't try to cram it all into a busy corner.
If you are having trouble identifying a cable as it passes through a bulkhead, tape a small bit of paper loosely round it, and push it through.
One you have established where a cable goes, wrap a label on it saying where. These can be made permanent later.
If you can't figure out where a wire goes, disconnect all the batteries and use a multi-meter or buzzer to identify it.
Where several cables go off in the same direction from a single connection, cable tie them together at intervals.
With the above, coloured cable ties can be used to identify common sources (red: battery+, yellow: ignition for example)
When you have finished, make a copy of the diagram on a computer to tidy it up.

 

[ghostlymoron]

Another tip for tracing wiring if you have another pair of hands/eyes is, if a wire goes through a bulkhead, you can waggle or pull it to and fro and your helper can then detect the movement. If you have a multimeter, you can twist the 2 wires to a light for example, together (after turning power off), and test for continuity at the panel end. A multimeter with an audible facility is a big help.

 

[yodave]

Slightly off subject, but the battery connection [on the left / bottom of photo] may require attention as the 2 large cables are connected with the butterfly nut.

The nut appears to have very little thread in contact with the nut [bolt too short]. If this fails you could loose all electrical supply, if it works loose you could have a burn up, an accident waiting to happen.

With regards to the black cable going to the selector switch, if it is a pos supply, put a ring of red tape either end to remind you.

Regards MM

malpasman: Thanks very much for pointing that out, as I didn't realise that there might be a problem. I'll have a look at it over the weekend. I'll also see if I can dig out some red tape.

 

[yodave]

rob2: I'll make sure that I take my multimeter with me - beginning to get the hang of it. Like you, I'm surprised that there seems to be no way of switching off the electrics completely, but that's how it seems to be set up. Thanks for your help.

sarabande: the batteries are out of the way, but I'm keen to take all the safety precautions that I can, so I'll have a look at plastic insulating covers ...I'm sure they'll be reasonably easy to track down on eBay or the likes. Thanks again!

nigelmercier: Thanks for the tips Nigel. It's useful to get all the insight I can to save going off with the wrong tactics.

ghostlymoron: more good tips. thanks for these, I'll print them out and take them with me.

Thanks to everyone who has taken the time to reply. It's been a great help.

 

[Rigger Mortice]

I'll double check whether the engine starts with the switch off over the weekend.

Be careful about trying that. You can damage your alternator if you start switching the master switch off with running engines. Best not to try it until you have somebody with you who knows what they are doing.

 

[yodave]

Be careful about trying that. You can damage your alternator if you start switching the master switch off with running engines. Best not to try it until you have somebody with you who knows what they are doing.

Rigger Mortice: Thanks for your input. I'm not planning on having the engine running with the master switch off, but I may try to start the engine with the master switch off (I don't expect that to work). Essentially, I'm going to have the master switch off ...then one-by-one try to operate all the electrical equipment, to find out which ones bypass the master switch. Hopefully I'll learn something by going through this process. Thanks again.

 

[nigelmercier]

nigelmercier: Thanks for the tips Nigel. It's useful to get all the insight I can to save going off with the wrong tactics...

What a polite chap you are, it isn't easy to do the individual thanks as you have.

I almost envy you, I had great find finding out how my boat worked.

If you decide to know more, you will find this book invaluable, regarded by many as the bible:
Boatowner's Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems by Nigel Calder:
http://www.amazon.co.uk/exec/obidos/ASIN/0713672269/dolcetto-21

 

[yodave]

nigelmercier: Thanks Nigel. I just reckon that if fellow members have taken the time to look at the issues and contribute, then the least I can do is (try to) thank them, and where possible leave comment that might be useful to others.

I'm in no way a handyman, but I've had to change my outlook on that over the last two years, and now I even find myself fixing things at home instead of simply replacing them. Recently I fixed the dishwasher which would otherwise have been heading for the skip.

Thanks for the link to the book, I'll have a look at that ...as a having a handy guide to hand might be a sensible precaution.

Best wishes!