Wiring my new horn - Any grounding wire?

Technical maybe guys, but also a recommendation for a frikking loud and easy fit airhorn! See link below.

http://cgi.ebay.co.uk/TWIN-AIR-HORN-NAUTILUS-LOUD-CAR-SAXO-VAN-BMW-FORD-MINI_W0QQitemZ260079941461QQihZ016QQcategoryZ15329QQrdZ1QQcmdZViewItem

I got an Airhorn in replacement for the stock Toyota shite a while ago and attempted to fit at weekend. It uses the standard spade connector which needs a little trimming, but goes to the positive terminal. I then got some normal 'wiring' from a toolbox and grounded the horn to the chassis of the car from the negative terminal. The horn worked perfectly, but as I was only testing it and just touched the wire on the chassis, I think it caused a surge which blew the fuse.

I've now got some decent female spade connectors to ensure a secure connection to the neg terminal on the horn and will wire this to the chassis.

What I need to know is can I use any grounding wire, or do I have to use a specific ampage/type? The fuse for the Haz/Horn is 15amp.

Thanks guys.

Greg

Thats odd most horns use a positive feed and the ground is the horn button.

It did come with a Relay box Tricky, but can't be arsed to chop the wiring if it works without, which it does. It also advises that it's not needed in most circumstances.

This may help. The horns are indeed grounded - so's the switch.

It's all done through a relay.