Technical information

1.3.1.5 Branch Circuit Protection (BCPD)

140-U 140F fuse holder 140M

The protection of the motor starter from the short circuit can be done in different

ways

The most used components are: fuses, manual self-protected motor controller

“type E”, automatic circuit breakers.

THE FOLLOWING ARE NOT ALLOWED: modular miniature circuit breakers

(with the exception of those with UL 489 approval), motor controllers that are

NOT “type E”, fuses approved for control circuits.

The size/calibr

ation of the protection m ust not be more than the low est v alue

between the two f ollowing v alues:

1) the product of the motor's full load current by a tabled coefficient; or

2) the required current from the restrictions shown on the approval “marking” of

power components down line from the protection in question: in particular

of contactors and overload protections.

Two fundamental data are required by the NRTL at the time of the

certification: the type of short-circuit protection to be used and its maximum

current size.

If the size/calibration of BCPD is not above 115% of motor nameplate FLA, then it

can also serve as overload protection.

The coefficients indicated in point 1) of the preceding list have been tabulated for

every type of protection and motor.The table is identical in any standards.

An extract from NEC follows :

BRANCH CIRCUIT