A 500 kva transformer feeds a 120/ 208 power distribution cabinet. Three 4 inch conduits run between the transformer secondary cabinet and the power cabinet with a 1200 amp main. They are stubbed up on both ends with bonding bushings. There is also a single 4 inch conduit in the primary cabinet on the transformerwith a bonding bushing as well. The inspector is claiming the 3/0 bonding conductor joining the bushings in the transformer is too small. He is using table 250.66. I went by table 250.122 and used 3/0 as a bonding conductor on both ends of the stub ups. Any thought? Thanks
Bonding conductor size
- Thread starter jimmac49
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250.122 would be correct on a circuit with an overcurrent protection device (such as the transformer primary)
250.66 would be correct for sized the jumpers on the transformer secondary.
That said, you might look at 250.102.. If you ran individual jumpers to each of the conduits, the bonding jumper is based on the pahse conductor in that conduit, if you ran one jumper to catch all conduits, then the size is based on the sum.
250.66 would be correct for sized the jumpers on the transformer secondary.
That said, you might look at 250.102.. If you ran individual jumpers to each of the conduits, the bonding jumper is based on the pahse conductor in that conduit, if you ran one jumper to catch all conduits, then the size is based on the sum.
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no problem, nobody challanged that so we are good to go
a lot of that is based on experience and I don;t like answering where I can't go directly to the Code and verify. In this case, the Code references hid from me, but I'm relatively confident on the advice.
Sorry I can't provide exact references if you need them.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
What size conductors do you have on the secondary?
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