What is the allowable voltage drop in a residential system for branch circuits?

In residential systems, the allowable voltage drop for branch circuits is typically 3%. This standard is established to ensure that electrical devices receive sufficient voltage for optimal performance and safety. A lower voltage drop helps improve the efficiency of electrical systems, particularly in longer runs where the resistance can lead to significant losses.

Maintaining a voltage drop of 3% means that the voltage at the furthest outlet in the circuit remains sufficiently close to the supply voltage. This is important to prevent potential issues with appliances and lighting that may be sensitive to voltage fluctuations, ensuring they operate correctly and reducing the risk of equipment damage.

In contrast, higher percentages of allowable voltage drop such as 5% or 10% can lead to noticeable degradation in performance. Additionally, a 1% drop is more stringent and typically applies to sensitive electronic equipment rather than general branch circuits in residential applications. Therefore, adhering to a 3% voltage drop is both practical and effective for typical residential systems.