Hi
I’ve just acquired a battery isolation switch, the type that clamps onto the battery pole. Does it matter which pole I attach it to? No instructions came with it. Don’t want to blow something!
Phil
Hi
Most I have seen are on the positive side as it sthe Live side.I believe its to protect from fire etc
If it’s the discarnect type, has a green or black screw knob, they are designed to fit on the neg terminal, I think the
neg post on the battery is slightly smaller than the pos.
I have one of these on my car, it’s great if you don’t use the car every day, it stops the battery fron draining.
Ian 
Many thanks for the prompt reply
Hmmm . . .
I picked up this item at the NEC last year from a parts stand. It was piled in a box with many more, all with no name or logo. Its made of brass with a black rotating knob on top and a secondary wire containing a fuse. (There’s a pic if it in this weeks Classic Car Weekly). It does fit the negative post, but I have a MK1 and the space to attach it is so small I can only just get a hand in there to operate the switch and have to remove the battery cover each time which defeats the object of being able to isolate quickly. Hence my question, can it be attached to the positive side which would make life so much easier as my ‘5’ is not used every day either.
Yep, that’s the one. It fits on the neg, got on on both my 5’s, they cost about £5.00 each.
Ian
The ones with the green knobs are cheap Chinese knock-offs. They are poor quality.
And the threads mash up easily.
The original, the Discarnect, has a black knob, and comes with a distinctive set of fuses.
This is what Mx5parts sells.