Real-World Answer

In practice, the calculation of voltage drop for conductors supplying a motor

does not typically consider the 125% FLC (Full Load Current).

Reason

The 125% FLC is a requirement for branch circuit sizing in order to provide adequate protection against short circuits and overloads. However, voltage drop is calculated under normal operating conditions, not fault conditions.

Code Requirements

The National Electrical Code (NEC) states that voltage drop calculations should be based on the average current demand under

normal operating conditions. This current will typically be less than the 125% FLC.

Impact on Voltage Drop

If the 125% FLC were used in voltage drop calculations, the resulting voltage drop would be overstated, potentially leading to unnecessary conductor upsizing. This can result in higher material costs and increased labor for installation.

Exceptions

There may be specific cases where the 125% FLC is considered in voltage drop calculations, such as: Installations where the motor is subject to frequent starting or high-inertia loads. Applications where the motor is operating at or near its maximum rated capacity on a continuous basis.In these cases, it is advisable to consult with an experienced electrical engineer or refer to manufacturer's recommendations.

Summary

For most practical applications, voltage drop calculations for conductors supplying motors should

not consider the 125% FLC. Using the average current demand under normal operating conditions will provide more accurate results. Flag for review