Re[2]: A Good Ground
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The proper ground for the HV supply is a ground wire that goes to the power system neutral at the electrical box. In most areas, it is hard to get a ground rod below 10 ohms resistance, so a driven ground rod may not have enough conductivity to be useful.

The National Electrical Code (NEC) calls for returning safety grounds to the system neutral through either an unbroken wire, or one with only a few electrically sound (wire nut) connections. Tom's electrician friend is correct that conduit grounds are unreliable. They are allowed by code for 240V systems, that have no 120v equipment. But if there is any 120v supply, there must be not only the electrical common (white wire) but a green safety ground, of similar conductivity as the circuit wires. Both white and green go to the system neutral at the power distribution box (panel).

A good husky ground strap, that is the first thing you connect when hooking up the fusor, is a very sound idea. It needn't be huge because of current handling concerns, just large enough to be physically robust. I use #12 green stranded with crimped and soldered ring connectors on the ends. The ring connectors won't pull off a ground stud, when you tug a little harder unexpectedly.

Some people prefer the bare ground braid, since you can more easily tell if it is healthy. It should also have lugged connection, if at all possible.

For HV connections, plain old stranded copper spark plug wire is great. It is good for 50 to 60 kV to ground, and thus very forgiving of an accidental lapse of safety procedures....( like brushing it with your hand.. doing some thing with voltage still on. )

It is a good idea to write out a safety procedure for yourself and try to follow it each time. The good habits formed will undoubtedly save your life one day.

Dave Cooper


Created on Sunday, May 27, 2001 10:56 PM EDT by David Cooper