hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Please ignore my ignorance I do need help as I am stuck in this matter. I hope this thread does not get closed. However it appears on plans.
Assume listed service rated fire pump controller that has breaker inside it. No other breakers are provided outside of the fire pump controller.
NEC 2014 section 695.4(B)(2)(a)(2) says:
“Overcurrent protection shall be provided by an assembly listed for fire pump service and complying with the following:
a. The overcurrent protection device shall not open within 2 minutes at 600 percent of the full load current of the fire pump motor(s)
b. The overcurrent protection device shall not open with a re start transient of 24 times the full load current of the fire pump motor(s)
c. The overcurrent protective device shall not open within 10 minutes at 300 percent of the full load current of the fire pump motor(s)
d. The trip points for circuit breakers shall not be field adjustable.”
However NFPA 20 2013 10.4.4(1) 600 percent and 300 percent of full load times are different says:
“For a squirrel cage or wound rotor induction motor, the (overcurrent protection) device shall be of the time delay type having tripping times as follows:
(a) Between 8 seconds and 20 seconds at locked rotor current (6 times full load motor)
(b) Three minutes at a minimum of 300 percent of motor full load current”
Manufacturer data sheet of the controller says it complies with NEC 695 and NFPA 20.
However I am confuse as to breaker inside the controller satisfy both two different conditions with two different times at 300% and another at 600% full load? Is this a discrepancy between NEC 2014 695 and NFPA 20 2013 chapter 10?
Assume listed service rated fire pump controller that has breaker inside it. No other breakers are provided outside of the fire pump controller.
NEC 2014 section 695.4(B)(2)(a)(2) says:
“Overcurrent protection shall be provided by an assembly listed for fire pump service and complying with the following:
a. The overcurrent protection device shall not open within 2 minutes at 600 percent of the full load current of the fire pump motor(s)
b. The overcurrent protection device shall not open with a re start transient of 24 times the full load current of the fire pump motor(s)
c. The overcurrent protective device shall not open within 10 minutes at 300 percent of the full load current of the fire pump motor(s)
d. The trip points for circuit breakers shall not be field adjustable.”
However NFPA 20 2013 10.4.4(1) 600 percent and 300 percent of full load times are different says:
“For a squirrel cage or wound rotor induction motor, the (overcurrent protection) device shall be of the time delay type having tripping times as follows:
(a) Between 8 seconds and 20 seconds at locked rotor current (6 times full load motor)
(b) Three minutes at a minimum of 300 percent of motor full load current”
Manufacturer data sheet of the controller says it complies with NEC 695 and NFPA 20.
However I am confuse as to breaker inside the controller satisfy both two different conditions with two different times at 300% and another at 600% full load? Is this a discrepancy between NEC 2014 695 and NFPA 20 2013 chapter 10?
