Technical information

For example the motor (FLA = 22 A) can be protected with time delay fuses

rather than an “Type E” combination motor controller.In this case the calculation

of the BCP would lead to a value of 35 A (for the calculation of the size please

refer to publication 3 “Branch Circuit” with J type 35 A fuses in the relative fuse

holder 1492 – FBJ60. The calculation of value a) now could be 35 + 8 + 4 = 47 A.

There is no longer incompatibility and the circuit breaker should have a size

between 40 and 47 A: the standard size suitable is 45 A and a 140U-H2C3-C45

can be installed.

3. Install a feeder conductor with a capacity of more than 40 A. In this particular

case a AWG 10 bearing 40 A has already been anticipated, therefore the same

140U-H2C3-C40 as previously defined can be used.

If an AWG 8 with a 60A capacity had been used it would have been possible to

use any 140 U with a size of between 40 A and 60 A, for example a 140U-H2C3-

C50.

For the best use of the switches with fuses it is sufficient to choose the fuse size

compatible with the calculations made above.

3.1 How to protect the electrical equipment from overcurrents

(feeder protection)

If we install a switch in the electrical equipment, the feeder circuit is extended as

far as the first branch protection (BCP red line in the figure);

What are the components that could be employed in the circuit feeder?

•UL 489 circuit breaker

•UL 248 fuses

The combination motor controllers are UL 508 certified and cannot be used.

FEEDER AND BRANCH CIRCUITS

Prot <= 60A

Sect. 1.25 x (22 + 8 + 4) >=42.5 A

Cond. 1.25 x 22 + 1.25 x 8 + 4 > = 41.5 A

AWG 8 (60A)