I have a 15KV service feeding two transformers. Each transformer feeds 480V distribution sections. Horizontal busing rated at 3000amps, vertical sections rated at 2000 Amp. The question is, If you total all the breakers amperage ratings up, can they exceed the sections amperage ? If so, does the type of load make a difference (in rush current) to the bus rating ?
Main distribution board, section amperage v.s. breaker amperage total
- Thread starter Danpk
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- Lockport, IL
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- Retired Electrical Engineer
The ratings of the breakers mean nothing. You can have a 100 amp breaker serving a load that actually draws only 20 amps. What matters is the calculated load.
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- Wisconsin
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- PE (Retired) - Power Systems
In your situation, the 'sum of the handle ratings' is important only if you are trying to apply the tap rules of 240.21(C) or the transformer protection Note 2 in table 450.3(b).
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