No Ground in Circuit panel.

[mac davis]

or as drunk Texans do around electric fences, pee on it..

[David Chamberlain]

The biggest problem is finding a good earth ground to use as a reference. If you have copper water pripe feeding the house or if you have a drilled well, you can probably be sure of a good earth ground. You use an ohmeter between your box ground and an actual ground. The resistance should be as close to zero as your meter can read. The higher the resistance, the more problems you can run into. Your box ground can start to float above zero volts.

I miss the good old days of copper tubing and metal pipe. If you had a 100 foot run of metal pipe going out to a drilled well with 60 feet of casing, you were pretty darn sure of a good ground. Even having 30 or 40 feet of copper tubing going out to the water main made a pretty sure round. Now with polybutelyne and other plastics in the system, it is harder to FIND a good ground to use as a test.

I am not sure what the NEC requires anymore but the 2 places I built had 2

10 foot ground rounds driven 18" below grade and tied to the box with good copper conductors.

[Bob Peterson]

Just what is a "box ground" versus a "good earth ground".

The reality is you cannot test earthing with a normal voltmeter and get anything even remotely resembling a result that is meaningful.

[David Chamberlain]

My meaning of a box ground is the ground bus inside your breaker box. An earth ground is an actual ground such as a ground rod or a buried length of pipe. An ohmeter is not the best tool but if the ohmeter measures a difference bewtween the two points then your breaker box groun is not really gounded.

[Bob Peterson]

This is sort of true. There should be a dead short between the ground bar in your service panel and your ground rod (or whatever you are using for your grounding electrode) and a normal VOM should show that.

However, its not a very definitive test since there could be a single strand of wire in an otherwise broken off ground wire that would still show as a dead short because VOM ohm ranges operate at a very low voltage and very low current. or someone might have run an undersized wire - the test would still show a short, but in both cases there is a major problem but the "test" shows OK.

If it shows an open circuit there is surely a problem.

if it shows some level of resistance above a dead short (even say 100 ohms) its hard to interpret. Could just be there is corrosion on the outside of the ground bar where you hooked up yet the connection itself is fine.