ECN Forum Forums General Topics of the Trade General Discussion Area When should a ground rod be replaced?

By the way we need to keep in mind who does what.

RODALCO and Trumpy both spend (or have spent) a lot of time working directly with high voltage distribution.

In my opinion that experience is far different from those of us that spend our time under 600 volts.

The effectiveness and necessity for good electrodes in high voltage distribution is greater than in our essentially 'low' voltage.

Say a homes service did not have a effective ground fault path and relied on just a grounding electrode.

Lets say that electrode had a 20 ohm resistance.

If we have a ground fault in that system you would only find 6 ams of current flow which will never trip a breaker in a home

120 volts / 20 ohms = 6 amps

On the other hand if the utility had the same ground fault on a 13,800 volt (7800 to ground) line things are greatly changed,

7800 volts / 20 ohms = 390 amps which is many, many times the value of the utility cut out (fuse) and will dump the circuit in short order.

Bob