I have a dust collection system that has a 3-phase, 208VAC, 20HP motor on it. The nameplate states the FLA is 52amps. It is currently being fed by a 3P/90amp circuit breaker that is connected to a fused disconnect with #4-THHN wire. The fused disconnect has dual-element time delay fused rated for 100amps @ 250VAC. Is this an acceptable installation? My calculations show that everything is too low.
Dust collection motor
- Thread starter thomrk
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Johnmcca
Senior Member
- Location
- Mid-Hudson Valley, NY
Read 430.52. Seems ok to me. Are you having problems with starting or running?
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
I like to size my fuses at about 140% of the FLA or maybe a bit lower. The code give maximums. Just keep some spare fuses. 100 Amps is way to big, it may be the fuse that would fit in the clips without reducers, and reducers are available.
Wires are 125% of code values
What type of overload is it? NEMA or IEC? IEC overloads have superior phase loss protection over NEMA.
As long as its not hard starting 140% of motorl FLA should be OK
Wires are 125% of code values
What type of overload is it? NEMA or IEC? IEC overloads have superior phase loss protection over NEMA.
As long as its not hard starting 140% of motorl FLA should be OK
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