Grounding Electrode T 250.66

[rrzzan]

Hi Guys,

I'm finding difficult to inteperate T 250.66

I have two parallel conduits, each having 2#500 kCMIL and 1#1/0 GND conductor. How do I size the grounding electrode?

T 250.66 says to consider equivalent area of ungrounded parallel conductors. One 500kCMIL has the area of 0.7073 in.

Thanks

 

[alehman]

First to clarify, T250.66 applies to grounding electrode conductors for services and separately derived systems. That is, the connection between the system neutral and grounding electrode.

If you have two 500kCMIL per phase (two-wire service?), then you need to add the areas (500+500=1000) and look up the GEC size in T250.66 for 1000kCMIL.

No offence, but if you don't understand the code at this level, please hire someone who does.

Alan
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