Russs57
Senior Member
- Location
- Miami, Florida, USA
- Occupation
- Maintenance Engineer
I'm not a code guy and don't have a code book. Saw something at work that I think is a clear violation. Need to draft a letter for the EE and I'd like to be reasonably correct so please help me out on what the code states (rather than just telling me to look at article 430-53 (a). Also make suggestions on how I can legally make the situation work.
Branch circuit is 120 VAC with 20 amp circuit breaker. Load is three 1/2 HP exhaust fan motors with a FLA of 7.2 and SFA of 8.4 and one 1/6 HP exhaust fan motor with a FLA of 3.6 and SFA of 4.0. Wiring is black, white, green #10 THHN in EMT. Motors are thermally protected with motor rated toggle switch at each fan. Clearly this is not okay (right?).
Correct me if I am wrong and fill in the missing parts. I can complain because codes says: Each motor has to be no more than 6 amps. OCPD shall not be less than 115% of sum of all FLA's. Conductor ampacity would be 125% of largest motor plus 100% of all the rest (#10 looks good at 27 amps). Would it be correct to say this arrangement is only allowed on a 20 amp circuit at 120VAC so he can't just change breaker to 30 amps? Is it correct to say a 20 amp breaker (of the type we are talking about) can't run continuously at more than 16 amps? These exhaust fans are in a hospital setting and I'm told they were inspected and passed. They want to start talking about actual amp draw being under 20 amps which is irrelevant to me as far as compliance (or maybe I am wrong?).
Lastly, what would be your cheap and easy solution to making it work? The 1/2 HP motors are 120 VAC only so going to 208 single phase and manual motor starters at each fan is out. Although I might be able to make them change out the motors. Doubt I have the panel space to add three additional breakers.
Branch circuit is 120 VAC with 20 amp circuit breaker. Load is three 1/2 HP exhaust fan motors with a FLA of 7.2 and SFA of 8.4 and one 1/6 HP exhaust fan motor with a FLA of 3.6 and SFA of 4.0. Wiring is black, white, green #10 THHN in EMT. Motors are thermally protected with motor rated toggle switch at each fan. Clearly this is not okay (right?).
Correct me if I am wrong and fill in the missing parts. I can complain because codes says: Each motor has to be no more than 6 amps. OCPD shall not be less than 115% of sum of all FLA's. Conductor ampacity would be 125% of largest motor plus 100% of all the rest (#10 looks good at 27 amps). Would it be correct to say this arrangement is only allowed on a 20 amp circuit at 120VAC so he can't just change breaker to 30 amps? Is it correct to say a 20 amp breaker (of the type we are talking about) can't run continuously at more than 16 amps? These exhaust fans are in a hospital setting and I'm told they were inspected and passed. They want to start talking about actual amp draw being under 20 amps which is irrelevant to me as far as compliance (or maybe I am wrong?).
Lastly, what would be your cheap and easy solution to making it work? The 1/2 HP motors are 120 VAC only so going to 208 single phase and manual motor starters at each fan is out. Although I might be able to make them change out the motors. Doubt I have the panel space to add three additional breakers.