Table

Single-Phase vs Three-Phase Voltage Drop Factors

Single-Phase vs Three-Phase Voltage Drop Factors reference with assumptions and boundary notes.

Reference boundary

Formula-factor reference only. It does not choose conductor size, overcurrent protection, or acceptable voltage drop.

Reference table

Compare the formula multipliers used for single-phase, three-phase, and DC voltage-drop estimates.

Formula basis uses standard circuit voltage-drop multipliers for preliminary arithmetic.
Circuit typeFormula multiplierCommon expressionUse
DC two-wire22 x I x R x LTwo conductors carry the circuit path
Single-phase two-wire22 x I x R x LLine and return conductor path
Three-phase1.732sqrt(3) x I x R x LBalanced three-phase line-to-line estimate
Use notes
  • Use this table for preliminary reference and arithmetic checks only.
  • Confirm equipment ratings, product markings, installation conditions, utility requirements, and the local authority requirements before design or field use.