Yes you need one on the live and with VERY good reason. I wish I had fitted mine sooner than I did.
I posted this on Lcb earlier in the year.
"Having had a little acident I am in the market for a new watch.
I brushed past the battery with multimeter in my hand to measure a voltage. I wasnt really working on the car, just poped out to check somthing.
It arked and welded my watch to the battery tray and wouldnt let go.
The stainless strap glowed orange untill the pins in the strap melted and I was able to get it of. It dumped its full charge through my watch.
After getting back from A&E I have full thickness burns the size of a golf ball. And lesser burns to the size of a tennis ball on my inner wrist
I am told I will have at least a month to save up for a new watch before I can ware one again.
And no I hadnt got around to puting a rubber cap over the live terminal. "