What size wire do I need to run 100 amps to a detached garage 50 feet away in NB?

For a 100-amp service to a detached garage 50 feet away in New Brunswick, you'll need 3 AWG copper wire or 1 AWG aluminum wire, run through appropriate conduit or as direct-burial cable rated for underground installation.

The wire size calculation involves both the amperage and the distance to account for voltage drop. At 50 feet, a 100-amp service requires larger wire than you might expect because electrical current loses voltage over distance, and Canadian Electrical Code limits voltage drop to 3% for branch circuits and 5% for feeders.

For your specific situation, 3 AWG copper conductors (three insulated wires plus a ground) will safely carry 100 amps at 50 feet with acceptable voltage drop. If you choose aluminum wire to save money, you'll need 1 AWG aluminum conductors. The complete installation requires four conductors: two hot legs (black and red), one neutral (white), and one equipment grounding conductor (green or bare copper). The grounding conductor can be one size smaller — 4 AWG copper or 2 AWG aluminum.

Underground installation in New Brunswick requires either direct-burial rated cable (like NMWU or ACWU) buried at least 18 inches deep, or individual THWN-2 conductors pulled through PVC conduit buried 18 inches deep. Many NB electricians prefer the conduit method because it allows for easier wire replacement in the future and provides better protection from frost heave and settling. The conduit should be Schedule 40 PVC, minimum 1.25-inch diameter for this wire size.

At both ends, the installation requires proper electrical panels and disconnects. Your main house panel needs a 100-amp double-pole breaker, and the garage needs either a 100-amp main breaker panel or a 100-amp disconnect switch feeding a sub-panel. The garage panel should be sized for your actual needs — many detached garages work fine with 60-amp or even 40-amp service, which would allow smaller, less expensive wire.

New Brunswick electrical code requires that all garage electrical work be performed by a licensed electrician with proper permits and inspections. The underground portion is particularly critical because improper burial depth, wrong cable type, or inadequate protection from physical damage creates safety hazards and code violations. An experienced NB electrician will also ensure proper grounding at the garage, which requires either connection to the house grounding system or a separate grounding electrode (ground rod) at the garage location.

Consider your actual power needs before committing to 100 amps. A typical two-car detached garage with LED lighting, several outlets, a garage door opener, and a small electric heater operates comfortably on 60 amps. You'd need 100 amps for high-demand equipment like a Level 2 EV charger (40-50 amps), large workshop tools, or electric heating for a large garage. Running oversized wire costs significantly more — 3 AWG copper costs roughly $8-12 per foot compared to $4-6 per foot for 6 AWG copper suitable for 60-amp service.

This is definitely professional electrician work — underground electrical installation involves trenching, proper cable selection, grounding requirements, panel installation, and coordination with your utility company for the service upgrade. Electrical permits in NB typically cost $100-200, and a complete 100-amp garage service installation runs $2,500-4,500 depending on site conditions and panel requirements.

Need help finding a licensed electrician for your garage electrical project? Find electrical contractors through the New Brunswick Construction Network directory.