How to Use Indoor Wiring in a Detached Garage

Updated April 17, 2017

Detached garages are a popular choice for homeowners who do not have the space to build an extension on their existing home or who wish to have an extra workshop. One of the last and most crucial steps to finishing a detached garage is to install electrical receptacles and outlets. Homeowners---with the help of city inspectors and some basic instructions following the local electrical code---can install almost all wiring to a professional level, without extra costs.

Contact the local Electrical Code and Municipal Building Code office to determine whether a permit is needed to install electrical work in your detached garage or if special restrictions apply. Circumstances, such as having city sewage lines running underground, may prevent certain installation methods from being used. The city also may be required to disconnect power or inspect electrical work during installation. Failure to contact the appropriate governing bodies or to acquire permits can result in fines, service disconnection or risk of electrocution and serious injuries caused by improper work.

Determine whether the electrical power will be run to the detached garage above or below ground. All power from the city must be turned off before installing wiring from the home to the detached garage. Overhead power supply should be wired from the main power supply conductors under the consultation of certified city power workers, while underground conductors must be buried in a trench between the main building or house and the detached garage. All main wiring exiting or entering the buildings must have a conduit installed on the side of the building or through a hole drilled in the concrete foundation.

Mount the main electrical panel and breakers according to standards outlined in the electrical code. Use the power drill to screw the electrical panel securely to studs or backing in the wall, and pry out the knockouts in the panel box with the screwdriver to install the circuit breakers. Wire all circuits and receptacles by using the wire cutters to cut wire to length, then stripping the ends being connected to receptacles or circuit breakers, using wire strippers. Wrap the bare ends of the wires around the appropriately-coloured screw on the receptacle, using the screwdriver to tighten the screws to hold the wire in place. Gently tug on the wire near each connection to ensure it is fastened properly.

Disconnect all power to your home, by arranging for city workers to shut off all electricity to your home. Use the volt/ohm meter to check that all wires are dead. Contact the city or a certified electrician for assistance, if electricity is still present. When the main feeds are proven to be carrying no electrical charge, install the main power feeds, the cables running from the main house under or above ground, to the main feed section commonly found at the top of the electrical panel. Once power is turned back on, test all breakers and safety features in the electrical panel to ensure they work properly. Contact a licensed electrician to troubleshoot or fix any problems, once power has been restored by the city.


Most circuit breakers are manufactured to be used with the same brand electrical panel. Avoid using any circuit breaker not recommended by the panel manufacturer.


All work must be done according to the minimum standards of your local electrical code. Failure to do so can result in serious electrical hazards or fines from the city. Include a copy of all plans, drawings and methods intended to be used to install all wiring when applying for a permit. Never use power tools, such as a power drill to tighten screws or fasten electrical components. Stripping the screw or excessive force can cause damage. Always wear personal protective equipment when doing electrical work, such as dry leather gloves, certified shock-resistant steel-toed boots and safety glasses.

Things You'll Need

  • Power drill
  • Screwdriver
  • Copper wire
  • Wire cutters
  • Wire strippers
  • Receptacles
  • Electrical panel
  • Circuit breakers
  • Conduits
  • Screws
  • Volt/Ohm meter
Cite this Article A tool to create a citation to reference this article Cite this Article

About the Author

David Hill began writing professionally in 2008. He has written for communities at Seneca College, where he studied the art fundamentals. Hill also studied art fundamentals at Sheridan College.