Grounding - Table 250.122

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orlandoengineering

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In Table 250.122 at the top of the heading reads 'Rating or Setting of Automatic Overcurrent Device in Circuit Ahead of Equipment, Conduit, etc'. What does this really mean? I have a code officical that gigged me 2 times for the following 2 situations:
1. I had a 1200 Amp MCB feeding a wireway with multiple 200 Amp meters and disconnects. FYI: PVC conduit was installed. The code official said that I had to size the ground conductor for the 200 Amp disconnect as a 3/0 since the 1200 Amp Breaker was ahead of the 200 Amp breaker, Do you agree?
2. A 400 Amp MCB panelboard with a 100 Amp branch breaker and feeder. Code official once again indicated that the 100 Amp feeder must have a #3 ground unless the conduit was all metal and served as the equipment grounding conductor. I had indicated a #8 ground for the 100 Amp feeder.

Is the code official correct?
 
Re: Grounding - Table 250.122

#1..Yes, he is correct.
#2..If the #8 is the EGC for the load side of the 100A breaker, he is incorrect.
Don
 
Re: Grounding - Table 250.122

I came up with my own answer, before I looked at the others. I have the same response. I guess it is true what they say, "Great minds drink alike." :D
 
Re: Grounding - Table 250.122

In number 1, can I assume 200A feeds being tapped off of a 1200A feeder in a wireway? Paralleled 600's? PVC conduits are from 1200A gear to wireway?

Anyway, the grounded conductor can be reduced in size to match the ungrounded tap conductors.

Doesn't look like the EGC can be reduced too?
 
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