Really stupid question sorry in advance

[Luckypants]

Originally Posted by Stu

Why?
If I understood, I might remember better. It's like jump starting, I know there's a best order, but always have to look it up (if I can be bothered)

Because if you are accidentally holding live with the earth connected, the battery can short through your body - a 12V battery can supply enough current to kill. Also if there is a complete circuit when you re-connect, the spark to the earth is a lot less than across the live.

Basically earth is a lot less dangerous than the live.

Originally Posted by Stu

Why?
If I understood, I might remember better. It's like jump starting, I know there's a best order, but always have to look it up (if I can be bothered)

If you disconnect the positive first and accidnelty touch your screwdriver to somewhere metal on the bike you could create a short circuit.

I started drafting a longer explanation than this but this is the nutshell version.

[Stu]

So if the battery is earthed the live is dangerous,
but if the battery is lived the earth is not dangerous?
OK I think I can follow that