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motor protection

A

anbm

Senior Member
Location
TX
Occupation
Designer
To protect a motor, why NEC article 430 has max. cb is sized at 250% x motor fla while if using fuse, it can be 175% x motor fla? CB trips faster than fuses?
 
A

anbm

Senior Member
Location
TX
Occupation
Designer
infinity said:
Are you comparing an inverse time breaker to a dual element time delay fuse?
Click to expand...
Yes, going with the attached table. For example, if the motor FLA is 12A, The required CB in panel = 12 x 2.5 = 30A, while the fused disc. at motor can be = 12 x 1.75 = 25A (round up to next standard fuse size).... to protect inrush motor starts, correct?
 

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