hatem_29
New member
- Location
- Jeddah, Saudi Arabia
Is there a violation in the NEC for rating circuit breakers more than 600 Amps in switchracks?
I have a problem in my project specifications, the drawings coming from the designer had a main breaker for the swichrack rated 1600AT/AF, and 5 motor starters rated 400A each. According to the clients specifications mentioned below the maximum permissible rating is 600A.
Is there any section in the NEC that can prove that this is a violation? If its not a violation, is there a reference for that?
15.3.4 Circuit breakers rated as part of a series rated protection system are
not acceptable (refer to paragraph 15.1.5).
(NA Supplement)
15.3.NA1 Circuit-breakers shall have the following additional
characteristics:
a) Be designed and tested to meet the requirements of
NEMA AB-1 and UL 489.
b) Rated Insulation Voltage (minimum): 600 V
c) Frame size:
minimum: 100A
maximum: 600A (for circuit breakers within
switching assemblies)
d) Rated Short Circuit Breaking Capacity (minimum):
i) For circuit breakers in, or connected to, the
main circuit: 10 kA
ii) For circuit breakers in auxiliary circuits: 10 kA
e) Rated Short-Time Withstand Current (minimum):
For breaker used as main circuit disconnector:
10 kA for 3 cycles
(IEC Supplement)
15.1.5 When a main circuit disconnector has been specified in Data
Schedule 1, it shall function to isolate the switchrack from the main
incoming circuit. This device shall have the following additional
characteristics:
a) For the purposes of meeting the short circuit interrupting rating,
shall not be, or considered to be, a short circuit protective device.
b) The switchrack shall not have more than one Main
Disconnector.
c) Shall not be equipped with instantaneous ground fault protection.
I have a problem in my project specifications, the drawings coming from the designer had a main breaker for the swichrack rated 1600AT/AF, and 5 motor starters rated 400A each. According to the clients specifications mentioned below the maximum permissible rating is 600A.
Is there any section in the NEC that can prove that this is a violation? If its not a violation, is there a reference for that?
15.3.4 Circuit breakers rated as part of a series rated protection system are
not acceptable (refer to paragraph 15.1.5).
(NA Supplement)
15.3.NA1 Circuit-breakers shall have the following additional
characteristics:
a) Be designed and tested to meet the requirements of
NEMA AB-1 and UL 489.
b) Rated Insulation Voltage (minimum): 600 V
c) Frame size:
minimum: 100A
maximum: 600A (for circuit breakers within
switching assemblies)
d) Rated Short Circuit Breaking Capacity (minimum):
i) For circuit breakers in, or connected to, the
main circuit: 10 kA
ii) For circuit breakers in auxiliary circuits: 10 kA
e) Rated Short-Time Withstand Current (minimum):
For breaker used as main circuit disconnector:
10 kA for 3 cycles
(IEC Supplement)
15.1.5 When a main circuit disconnector has been specified in Data
Schedule 1, it shall function to isolate the switchrack from the main
incoming circuit. This device shall have the following additional
characteristics:
a) For the purposes of meeting the short circuit interrupting rating,
shall not be, or considered to be, a short circuit protective device.
b) The switchrack shall not have more than one Main
Disconnector.
c) Shall not be equipped with instantaneous ground fault protection.
