Allowable Voltage Drop Link Jun 2026

| Load Type | Recommended Total Drop | Reasoning | |-----------|------------------------|------------| | Incandescent lighting | 3% | Visible flicker at 4% | | LED lighting | 3% | Driver input range | | Induction motor (continuous) | 4% | Starting torque margin | | Induction motor (intermittent) | 5% | Acceptable if start infrequent | | Resistance heating | 8% | Power drops as (V^2), but acceptable for non-critical | | Data center IT load | 2–3% | PSU hold-up time and efficiency | | Residential general use | 5% | NEC Informational Note | | Heavy industrial (welding, cranes) | 10–12% | By special allowance, with larger contactors |

As electrons move through a wire:

Voltage drop occurs when there is a resistance in the electrical circuit, causing a decrease in voltage as the current flows through it. This reduction in voltage can happen due to various factors, such as: allowable voltage drop