Fused Disconnect feeding breaker taps
Fused Disconnect feeding breaker taps
(OP)
Say you have three motors individually protected off a tap by circuit breakers that was sized at 225% of NEC table 430.250 and the feeder is protected by a fused disconnect would you size the fuse at a) Largest motor breaker size + FLA of other motor taps b) same as previous, but do calculations based on the largest protection being sized at 300% of FLA? c) something else.
The code seems to support option (a) but I would think that might create an opportunity to blow the service fuse on motor start up.
The code seems to support option (a) but I would think that might create an opportunity to blow the service fuse on motor start up.





RE: Fused Disconnect feeding breaker taps
RE: Fused Disconnect feeding breaker taps
You don't size generators to fit fuses, you size generators to handle loads. Fuses are the final step and are used to protect the conductors feeding those loads.
JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> FAQ731-376