No, should not harm anything. It just cuts down the chances of directly shorting the battery to earth. Things get jumpy then and sparks go fizz. Quite entertaining as an on looker, but makes me jump if it happens to me!!

Saying that though, a mate of mine burned himself quite badly once when he shorted the battery to earth through his watch strap. He jumped about then! And now, 12 years later, he still bears the scar.
