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Discussion Starter · #1 ·
What exactly does 250 v to ground mean?
Is this 1 phase to ground. Which for me would mean mostly the 277 v circuits where con or ecc ko s are present. If its single phase system they wouldnt be required anywhere or only load side 1st disconnect?


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Typically, you would be talking about a 277 volt circuit. The goal of 250.97 is sometimes two-fold.

The primary objective is to assure that the raceway or cable jacket is effectively bonded. In the instance where the raceway is used as an equipment grounding conductor proper bonding would be required from the raceway to the enclosure (if concentric or eccentric KO's are encountered).

The UL white book has information on boxes that may have eccentric or concentric KO's showing that the boxes still provide the required bonding without the use of additional fittings such as bond bushings.

The way I keep it straight in my head is to consider whether the enclosure is providing the bonding means for the raceway or is the raceway providing the bonding means for the enclosure.

Pete
 

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Discussion Starter · #5 ·
Thanks Mr Dennis and Mr Pete. I had a good idea of when its bonded well. Which means nothing. The code does. This helped me understand it better and explain it to those who way over bond


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