5 ohms or less

[iwire]

I have yet to see a job spec that does not specify a FOP test if they want the GES tested.

 

[big john]

Which assumes that the user of an integrated three point FOP tester actually runs a plot using different middle electrode positions instead of setting that probe at the "correct" distance and just reading the meter which pre-calculates the earth impedance based on an ideal voltage versus position plot.

Well, yeah, any test is fallible when it's done incorrectly. I know it's a common mistake, but I've never seen any literature that suggests only picking the 62% mark, and that's definitely not an IEEE test. Whereas you can do a clamp on test exactly like the instruction manual dictates and still get a wrong result.

One is a failure of methodology, which is fixable. The other is a failure of equipment, which ain't.