Grounding Electrode Conductor

[Parkview1956]

I would appreciate some feed back on the following scenario: 20Kw generator install, Service rated transfer switch. The grounding electrode conductor (#6AWG Cu) is run from the Meter Main to the grounding buss in what is now a subpanel, from the subpanel another #6AWG Cu is run to the cold water line. Is the connection compliant with NEC?

 

[Ponchik]

I am assuming the size of the service is 200Amps? If true then the GEC to the water pipe can not be less than #4 (250.66) and the EGC to the subpanel depends the OCPD that protects the feeder (250.122)

 

[__dan]

Maybe by exception. The guys here love these grounding questions so you should get a better answer.

2005 NEC, 250.64 C. The GEC is installed continuous, but a busbar termination is allowed between the GEC and a jumper from the busbar to the electrode. Minimum size of the common grounding busbar is given as 1/4" X 2" which is larger than most residential panelboard grounding busbars.

If the run from the electrode landed on the same busbar as the system bonding jumper, you would be Ok. I believe your question relates to the SBJ being in the other enclosure, the meter main, and you're asking about a compliant splice of the GEC on the grounding busbar in the subpanel. The subpanel busbar is probably too small for a compliant splice by exception in 250.64 C.

 

[Dennis Alwon]

A 20 kw generator is only 83 amps at 240v.