Skip to content
TECHNICLIGHTLighting Systems

Voltage Drop Calculator

Engineer

Calculate voltage drop from cable cross-section, length and current, and find a suitable cross-section from standard sizes.

System Voltage

Phase

Conductor Material

Cable Cross-Section
A
m
Voltage Drop
2.8 V
Voltage Drop Percentage
1.22%

Within the 3% limit

Voltage drop is the loss of voltage between the source (panel) and the load (fixture) caused by a cable's resistance — excessive drop can make fixtures run dimmer than expected or shorten driver lifespan. This tool calculates voltage drop using Vdrop=2·L·I·ρ/A for single phase and the simplified (reactance-ignoring) Vdrop=√3·L·I·ρ·cosφ/A for three phase, then compares it to the commonly accepted 3% limit. If the limit is exceeded, it suggests the smallest standard cross-section that meets it. The exact limit and the effect of reactance can vary by project specification or local regulation.