What is the maximum allowable voltage drop for feeders as per NEC guidelines?

The maximum allowable voltage drop for feeders, as specified by the National Electrical Code (NEC), is indeed set at 3% for feeders and 5% for branch circuits. This guideline is put in place to ensure that electrical systems operate efficiently and safely. A voltage drop that exceeds these limits can lead to performance issues for equipment and appliances, potentially causing them to underperform or sustain damage due to insufficient voltage.

The rationale behind the different allowable voltage drops for feeders compared to branch circuits is based on the distance electricity travels and the load demands. Feeders typically serve larger areas or load demands, which is why a higher percentage drop can be tolerated, as these systems are designed to handle larger loads. In contrast, branch circuits connect directly to specific devices or points of use, where maintaining a higher voltage level is crucial for proper operation.

By adhering to these voltage drop guidelines, electrical designers and contractors can ensure reliable performance of electrical systems, enhance energy efficiency, and mitigate the risk of overheating and other electrical issues.