How to Run Wire Across a Ceiling Joist

How to Run Wire Across a Ceiling Joist

Running wire across ceiling joists is straightforward when the attic is accessible — the wire can be laid flat on top of the joists or stapled to the side of the joists. When there is no attic access and the wire must run perpendicular to joists inside a finished ceiling, the standard approach is to drill through each joist using a right-angle drill and a long spade bit or auger bit, then pull the cable through. In both cases, the Canadian Electrical Code governs how cables are supported and where protection is required.

Methods

• From the attic: run cable parallel to joists by laying it along the joist bay, or perpendicular to joists by drilling through them — drill holes at the center of each joist to preserve structural integrity
• Finished ceiling (no attic): cut small access holes at each end of the run, use a right-angle drill to bore through joists, then fish the cable through with a fish tape
• Cables in the attic must be protected from physical damage if they are within 750mm of the attic access opening — use conduit or staple at regular intervals
• Cables run in accessible areas must be secured every 1.5m and within 300mm of each box

When Permits Are Required

Running wire across joists is typically part of a larger circuit installation — adding a new outlet, light fixture, or circuit. New circuits and extensions to existing circuits both require an ESA permit in Ontario. A Licensed Electrical Contractor pulls the permit and ensures the work is inspected. EZSMART runs circuits and wiring through finished and unfinished ceiling spaces across Ontario. Contact us for a quote on adding lighting or outlets to any room.

Amir Azimipour

Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp