Detached Garage Electrical

Detached Garage Electrical: Safe Power for Work and Storage

Detached garages are common in Calgary and often serve as workshops, storage spaces, or future rental units. Adding power to a detached garage requires more planning than a simple extension cord. This guide explains trenching, subpanels, grounding, and common problems so you can plan a safe, reliable setup.

Why Detached Garages Need Proper Electrical Planning

Detached buildings are separate structures, which means:

• Power must be delivered through underground or overhead feeders
• Grounding and bonding rules are different than inside the main house
• Load planning must consider lighting, tools, heating, and future additions

Skipping these steps can lead to unsafe wiring and frequent tripping.

Common Problems and Their Causes

1) Lights Dim When Tools Start

Cause: Undersized feeder or too much load on a small circuit.

Solution: Increase feeder capacity or add dedicated circuits for high‑draw tools.

2) GFCI Outlets Tripping

Cause: Moisture in outdoor or garage outlets.

Solution: Use weather‑rated covers and properly sealed boxes; replace any failing GFCI devices.

3) Overloaded Circuits

Cause: Multiple tools, heaters, and lighting on the same circuit.

Solution: Install a subpanel to distribute load across multiple circuits.

Trenching and Feeder Considerations

Power to a detached garage is typically supplied by an underground feeder. Important considerations include:

• Proper burial depth based on code and conduit type
• Approved conduit and cable types
• Clear separation from gas or water lines

Professional installation ensures code compliance and avoids damage during future landscaping.

Subpanel vs Single Circuit

Single Circuit

Best for basic lighting and a few outlets, but limited capacity.

Subpanel

Recommended for workshops, EV chargers, heaters, or future expansion. A subpanel provides multiple circuits and easier load management.

Grounding and Bonding

Detached buildings typically require their own grounding electrode system. Improper grounding is a common cause of shock hazards and equipment failure.

Heating and High‑Draw Loads

If you plan to heat the garage or run heavy tools, plan for it in advance:

• Consider dedicated circuits for heaters and compressors
• Size the feeder to handle startup surges
• Avoid plugging heaters into general‑purpose outlets

Lighting and Convenience

• Use bright, even lighting for workshop safety
• Add task lighting where detailed work is done
• Install plenty of outlets to reduce extension cord use

Proper lighting improves both safety and functionality.

When to Call a Licensed Electrician

Detached garage wiring involves trenching, feeder sizing, and grounding—tasks that should be handled by a professional. Call a licensed electrician when:

• You need a new feeder or subpanel
• You plan to add heating or high‑draw equipment
• You need to confirm grounding and bonding compliance

Detached Garage Checklist

• Feeder sized for current and future loads
• Proper burial depth and conduit
• Subpanel installed if multiple circuits are required
• GFCI protection in required areas
• Adequate lighting and outlet coverage

Closing Thought

A detached garage can be a safe, functional workspace when the electrical system is planned correctly. With proper feeder sizing, grounding, and circuit distribution, the space will handle current needs and future upgrades without repeated electrical issues.