OK I guess someone with proper electrical knowledge can probably put me straight on this right away ...

.... but if I wanted to fit a red plastic key style battery isolator to the Fug to ensure all electrics are dead when it's left anywhere could it go on the earth side rather than the positive side? And if not why not?

Cheers

Paul.

This is interesting but the arguments only really seem to apply to boats.

http://www.smartgauge.co.uk/whereiso.html

Mine had earth side switch when I got it, given that when working on the electrics the advice given (Haynes manuals etc) is to remove the earth cable from the battery before work, I presume it's fine and mine will stay.

if you want just an on/off battery switch then the neg side is fine..and easier.
cant remember if it can hurt a dynamo if switched off when running, but it can fry the diodes on an alt system. 9 times out of 10 it will be fine (if switched off when engine running) but you can take the key out to stop that from happening.
otherwise you need the bigger switch with the extra terminals, so the alt can dump its charge to earth...full instructions should come with the switch.

Thanks all - looks like it'll go in the earth side then!

Given it's got a lot of exposed nuts on the back it also seems a heck of a lot safer. Not sure quite why we were convinced that it had to go in the live side.

Just read the instructions with my new swtch....... It says either - or + but warns not to switch off while engine running or the alternator will fail! :o