3-wire Grounding schemes

danf said in another posting: "...The ST-70 in particular has a sophisticated ground scheme that is very easy to use with a three wire cord. The only potential hum issue is a ground loop with grounded preamp...."

I can just see (in my mind's eye) a friend or relative's kid poking his finger aorund my "stuff" and something bad happening, with the aftermath including lawyers etc and questions coming up about the "safety" of my equipment. Danf / Bob: Assuming that I know how to (otherwise) prevent ground loops etc., how do you properly run a ground wire? Just screw the ground directly to the chassis?

Thanks in advance!
-- JunkyJan

Hi Jan,

The grounding protects you as well your guests, and is worth doing even if there are no kids around your equipment. You want to place the ground close to the point where the power cord enters the chassis or near the IEC connector and connect it solidly electrically and mechanically to the chassis. A good article to read is:

http://sound.westhost.com/earthing.htm

If you are worried about kids touching your amps, please also remember that there are dangerous voltages on the driver board that are exposed if you run without a cover.

Safety practices were more casual when most tube amps were built. In my view, the emphasis on improved electrical safety since then is just common sense.

Dan

Man, I better be careful when I'm showing my buddies my amp...

Can just picture it ... "...here's the new VTA board, and these are some of these here new caps they use, and right here... BZZZZT!"

danf wrote:
If you are worried about kids touching your amps, please also remember that there are dangerous voltages on the driver board that are exposed if you run without a cover.

Incidentally, the kind of shock you would get from the dangerous voltages on the driver board would NOT be prevented by a third-wire ground. Regardless of whether the chassis is third-wire grounded or not, the potential from those points to the chassis remains the same.