Harold E. Johnson wrote:
Interesting. Here in Florida, the lightning capital of the continental
US, the ordinary electrical service grounding mechanism is *only* via
bonding to the metal in the foundation. New house construction will not
pass inspection without such a connection unless other more complex
arrangements are fashioned. There are typically no driven ground rods, and
water pipes are usually non-conductive. (The NEC no longer allows water
pipes to serve as the sole ground in any case.)

73,
Gene
W4SZ

Must be a recent rules change Gene. I used to manufacture and sell an
instrument to the power companies in FL, a meter that they would connect
between one 120 Volt leg of the service drop and the residential ground rod,
and drive the rod for a 25 Ohm ground. Typically, if they were installing
pad mount transformers for underground service, they would install another
ground rod there.

The Withlacoochee Co-Op, which serviced some of the highest sand dunes in
FL, would often drive 60 feet of ground rod to reach the required
conductance.

W4ZCB



I don't know when the change was made. I discovered this rule when our
house was being built in 2003. I noticed that there were no ground rods,
and I started asking questions and looking into the code. Florida
follows the NEC without exception. No modifications or local electrical
codes are allowed. Of course the AHJ can override almost anything if he
decides to.

As you know, the electrical utilities generally are not bound by the NEC
or other codes. They follow their own rules. Also, there are a lot of
preexisting cases where the foundation steel is not connected to the
outside of the concrete. Ground rods must be used. In those cases your
ground-checker instrument would still be useful.

73,
Gene
W4SZ