CEC Voltage Drop Calculator
Size your conductors right the first time. Built on CEC Rule 8-102 and Table D3—mandatory limits, not recommendations.
Switch to NECHow We Calculate Voltage Drop (CEC)
This calculator uses resistance values derived from CEC Appendix D, Table D3 which provides "Distance to centre of distribution for a 1% drop in voltage on nominal 120V, 2-conductor copper circuits."
Where:
- Vd = Voltage drop in volts
- L = One-way length in metres
- I = Load current in amperes
- R = Resistance in Ω/km (derived from Table D3)
CEC vs NEC: Critical Differences
MANDATORY vs Informational
CEC Rule 8-102 uses "shall" making voltage drop limits legally enforceable code requirements. NEC voltage drop values are informational notes—recommendations only. This is the most important difference for Canadian electricians.
Circuit Type Matters
CEC distinguishes between feeders (3% max), branch circuits (3% max), and combined total (5% max). Select the appropriate circuit type to see the correct limit applied.
Metric Units
CEC uses metric: distance in metres, resistance in Ω/km. This calculator handles all conversions automatically—enter your distance in metres and we do the rest.
Canadian Voltages
Canada commonly uses 347V and 600V for commercial/industrial (vs US 277V and 480V). The voltage presets reflect Canadian standards.
CEC Voltage Drop: What Canadian Electricians Must Know
What are the CEC voltage drop requirements?
CEC Rule 8-102 establishes mandatory voltage drop limits:
- Rule 8-102(1): Feeders shall not exceed 3% voltage drop
- Rule 8-102(2): Branch circuits shall not exceed 3% voltage drop
- Rule 8-102(3): Total voltage drop (feeder + branch) shall not exceed 5%
Unlike NEC, these are mandatory requirements, not recommendations. Inspectors will enforce them.
How does CEC handle aluminum conductors?
Per CEC Table D3 Note 5, aluminum conductors have equivalent resistance to copper conductors that are two AWG sizes smaller.
- 6 AWG Aluminum = 8 AWG Copper
- 4 AWG Aluminum = 6 AWG Copper
- 2/0 AWG Aluminum = 1/0 AWG Copper
When you select aluminum in this calculator, it automatically uses the appropriate copper equivalent values from Table D3.
What is Table D3 and how is it used?
CEC Table D3 provides the maximum distance (in metres) for a 1% voltage drop at 120V for various wire sizes and currents. It's a lookup table that simplifies calculations.
This calculator derives resistance values from Table D3 for use in the standard voltage drop formula, allowing it to calculate any voltage, current, and distance combination.
Key Table D3 notes:
- For 3% or 5% drop, multiply distances by 3 or 5
- For voltages other than 120V, multiply by (voltage/120)
- Values are based on 60°C conductor temperature
Why does CEC use 347V and 600V?
Canada uses different standard commercial/industrial voltages than the US:
- 347V (Canada) vs 277V (US) — single-phase from 600V/480V 3-phase
- 600V (Canada) vs 480V (US) — 3-phase distribution
This dates back to different utility standards. The higher Canadian voltages actually help reduce voltage drop on long runs.
What temperature correction factors are available?
CEC Table D3 includes correction factors for different conductor insulation temperatures and loading percentages. These account for the fact that conductors run hotter under full load, increasing resistance.
The base values in Table D3 assume 60°C conductor temperature. For 75°C or 90°C rated insulation (like RW90), correction factors adjust the calculation.