What is the maximum allowable voltage drop from the service point to the last over-current device in a dwelling unit?

The maximum allowable voltage drop from the service point to the last over-current device in a dwelling unit is generally considered to be 3%. This value is recommended to ensure that electrical devices operate efficiently and safely. Excessive voltage drop can lead to reduced performance and may even damage appliances or electronic equipment.

In residential settings, the guideline aims to balance the operational efficiency of electrical systems with the necessary safety standards. The value of 3% is based on industry standards that account for the typical voltage loss acceptable in residential wiring; this ensures that there is sufficient voltage for appliances at peak demand while minimizing energy loss over the wiring distance from the service point.

Thus, while options may propose other percentages for maximum voltage drop, the 3% figure represents a widely accepted standard for residential applications, emphasizing safety and reliability in electrical installations.