430.24 & 240.4

[Smart $]

From all replies i can understand there is no any possiblity of overloading in feeder independently*from motor overloading.

When motors supplied by a feeder are individually protected against overload as required, the feeder is protected against overload, as long as it is properly sized/rated for the combined loads. When properly sized/rated, feeder ampacity will never be less than the combined ratings of overload protection. Can you provide an otherwise compliant scenario which refutes the preceding statement?

 

[m sleem]

When motors supplied by a feeder are individually protected against overload as required, the feeder is protected against overload, as long as it is properly sized/rated for the combined loads. When properly sized/rated, feeder ampacity will never be less than the combined ratings of overload protection. Can you provide an otherwise compliant scenario which refutes the preceding statement?

If we assume that all overloading faults caused by the motors, so the feeder is protected enough by the branch overload protection.

But, i proposed an overloading would be occurred due to losing part of the insulation while current passing through, but Don disagree with me :weeping:

 

[petersonra]

If we assume that all overloading faults caused by the motors, so the feeder is protected enough by the branch overload protection.

But, i proposed an overloading would be occurred due to losing part of the insulation while current passing through, but Don disagree with me :weeping:

I don't see how an overload could happen because of insulation failure. Maybe a short circuit.

 

[david]

If we assume that all overloading faults caused by the motors, so the feeder is protected enough by the branch overload protection.

But, i proposed an overloading would be occurred due to losing part of the insulation while current passing through, but Don disagree with me :weeping:

Are you sure you are defining an over load the same as others in this discussion?

 

[m sleem]

Are you sure you are defining an over load the same as others in this discussion?

Overload for me equals to approx 6x flc, i was learned that losing insulation leading to overheating, similar to loose connection. May be i'm wrong.

 

[don_resqcapt19]

Overload for me equals to approx 6x flc, i was learned that losing insulation leading to overheating, similar to loose connection. May be i'm wrong.

The definition of terms may be part of the issue. This is an NEC forum, so the definitions that apply are those found in the NEC, especially those found in Article 100.

Overcurrent. Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result
from overload, short circuit, or ground fault.
Informational Note: A current in excess of rating may be accommodated by certain equipment and conductors for a
given set of conditions. Therefore, the rules for overcurrent protection are specific for particular situations.

Overload. Operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated ampacity
that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload.

An insulation failure is either a short circuit or a ground fault, I don't see it as an overload. Loose connections do not normally case "overcurrent", but they often cause conductor and or equipment damage from excessive heat.