What is the allowable maximum total voltage drop percentage when sizing feeder conductors for reasonable efficiency?

When sizing feeder conductors, an allowable maximum total voltage drop percentage is significant for ensuring efficient operation of electrical systems. A total voltage drop of 5% is recognized as a standard guideline for feeder conductors. This percentage balances efficiency and performance; it allows for adequate voltage at the load while minimizing energy loss in the conductors.

A 5% voltage drop is often considered the limit for branch circuits, with the understanding that keeping the voltage drop lower than this threshold can improve energy efficiency and equipment performance. It ensures that electrical equipment operates effectively without excessive heat generation or performance issues due to voltage drops, which can lead to reduced lifespan and functionality of appliances and tools fed by the system.

The other options – 3%, 7%, and 10% – do not align with the commonly accepted standards for efficient electrical design. A 3% drop is typically more stringent and is often applied to branch circuits instead. A 7% or 10% drop would be excessive for feeders and could lead to significant inefficiencies, equipment malfunction, and safety hazards due to inadequate voltage levels at the point of use. Thus, 5% serves as a reasonable compromise for feeder conductors, promoting energy efficiency while meeting the operational needs of the electrical system.