What size wire do I need for a 240-volt circuit to my workshop in New Brunswick?

Wire size for a 240V workshop circuit depends on the amperage of your equipment — the Canadian Electrical Code requires specific wire gauges to safely carry the load without overheating.

Common 240V workshop circuits and wire sizes:

| Equipment | Typical Amps | Breaker Size | Wire Size (Copper) | Wire Size (Aluminum) |
|-----------|-------------|-------------|-------------------|-----------------------|
| Welder (small) | 30A | 30A 2-pole | #10 AWG | #8 AWG |
| Table saw | 20-30A | 30A 2-pole | #10 AWG | #8 AWG |
| Air compressor | 20-30A | 30A 2-pole | #10 AWG | #8 AWG |
| Welder (large) | 40-50A | 50A 2-pole | #6 AWG | #4 AWG |
| Sub-panel feed | 60A | 60A 2-pole | #6 AWG | #4 AWG |
| Sub-panel feed | 100A | 100A 2-pole | #3 AWG | #1 AWG |

Important CEC rules:

• These sizes are for copper wire at standard temperatures with runs under 50 feet. Longer runs may require upsizing one gauge to prevent voltage drop
• Aluminum wire requires one size larger than copper for the same amperage
• All 240V circuits require a 2-pole breaker — the wire needs two hot conductors, one neutral (sometimes), and one ground
• Wire in conduit may need to be derated if running alongside multiple other circuits due to heat buildup

Voltage drop matters for long runs:

If your workshop is in a detached garage or barn far from the house panel, voltage drop becomes a real issue:

• Under 50 feet: Standard wire sizes above are fine


• 50-100 feet: Consider upsizing one gauge (e.g., #6 instead of #8 for 40A)


• Over 100 feet: Definitely upsize — or install a sub-panel in the workshop fed by a larger feeder cable

Voltage drop causes motors to run hot, start slowly, and potentially burn out. A licensed electrician will calculate the exact voltage drop for your specific distance.

For a detached workshop in NB:

Running wire to a separate building requires:

• Underground burial in conduit at minimum 24-inch depth (CEC requirement)


• Separate grounding electrode (ground rod) at the workshop


• Neutral and ground separated in the sub-panel (not bonded like in the main panel)


• Weatherproof entrance fitting where the wire enters the building

NB-specific considerations:

• Rocky soil common across NB makes trenching difficult — budget extra for excavation


• Frost depth of 48-60 inches in northern NB means underground conduit should include expansion fittings


• TSANB permit required for all new circuits — your electrician will handle this

Cost in New Brunswick:

• Single 240V circuit (under 50 feet): $500-$1,000


• 100A sub-panel to detached workshop: $3,000-$5,000 including trenching


• TSANB permit: $100-$200

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