What is acceptable voltage drop on a 347V circuit?

Most engineers target 3% or less on branch circuits. Over 5% total (feeder plus branch) is generally considered poor practice. Check your local authority having jurisdiction.

What wire size should I use for a 347V circuit?

Wire size depends on load current, run length, and acceptable voltage drop. Use the voltage drop calculator linked above to find the right gauge for your specific run.

Voltage Drop at 347V (Single-Phase AC)

347V is commonly used for lighting in Canadian and large commercial 600/347V systems.

Open 347V Voltage Drop Calculator with Example Values →

Why 347V Systems Need Attention

At 347V, voltage drop matters less on short runs but becomes significant over long feeders in large buildings or industrial plants.

Example Calculation

For a 347V Single-Phase AC circuit at 20 A over 150 ft using 10 AWG copper:

Voltage drop = 2 x I x R = 2 x 20 x (ohms per ft for 10 AWG x 150 ft)

Run this example in the calculator →

Common Applications at 347V

Commercial lighting
High-bay fixtures
Building lighting panels

Common Questions

What is the acceptable voltage drop for a 347V circuit?

Most engineers target 3% or less on branch circuits and 5% total (feeder plus branch). These are general guidelines, not hard NEC requirements. Check your local code.

What wire gauge should I use for a 347V circuit?

It depends on load current and run length. Use the voltage drop calculator with your specific values. A longer run or heavier load requires a larger gauge.

Does voltage drop affect safety?

Excessive voltage drop can cause motors to overheat, breakers to nuisance-trip, and equipment to malfunction. It is not just an efficiency issue.

Can I use aluminum wire on a 347V circuit?

Aluminum is commonly used for larger feeders (service entrances, subpanel feeds). For small branch circuits, copper is generally required. Aluminum has higher resistance than copper for the same gauge, so voltage drop is worse for the same wire size.