ECN Forum Forums Code Related Discussion Canadian Electrical Code Topics Dial Setting for Overload Protection

The trip values for motor overloads are as per OESC Rule #28-306 . . .

However, if you follow manufacturers instructions, you would be suprised to discover the following:

For Motors with a Service Factor of 1.15

Set the dial setting to the motor nameplate full load amperes.

Then the device trips at 125% of the full load amperes.

For Motors with a Service Factor of 1.00

Set the dial setting to only 90% of the motor nameplate full load amperes.

Then the device trips at 115% of the full load amperes.


Tony Moscioni
Electrical Inspector
Electrical Safety Authority

- - - and for motor starters that require overload heaters to be installed in the field, the heater specified on the instructions are for motors with a Service Factor of 1.15.

For motors with a Service Factor of 1.00 you must install one heater size smaller in order to provide proper protection.

Ed