What is Romex wire and is it up to code in Ontario?

Romex is a brand name for non-metallic sheathed cable (NMD90 in Canada) that's widely used for residential wiring and is absolutely code-compliant in Ontario when properly installed.

Romex cable consists of two or more insulated conductors (hot and neutral) plus a bare ground wire, all wrapped in a plastic sheath. In Canada, the equivalent cable is typically labeled NMD90 (Non-Metallic Dry, 90°C rated), which meets the same function as American Romex but is manufactured to Canadian standards. You'll find this cable used throughout Ontario homes for standard 15-amp and 20-amp circuits powering outlets, lights, and most household appliances.

The Ontario Electrical Safety Code (OESC) fully permits NMD90/Romex cable for residential installations, with specific requirements for its use. The cable must be supported every 1.5 meters and within 300mm of every box or fitting. When running through framing members, it should be at least 32mm from the edge of studs and joists, or protected by nail plates if closer. The cable cannot be used in wet locations, buried directly underground, or in areas subject to physical damage without additional protection.

Installation requirements under ESA regulations include proper stapling techniques - you cannot drive staples so tight that they damage the cable sheath, and the cable must maintain its round shape. When entering electrical boxes, NMD90 cable requires proper cable clamps, and at least 150mm of free conductor length must extend into the box for connections. The cable is rated for dry locations only, so areas like unfinished basements, garages, and outdoor applications require careful consideration of moisture exposure.

For most homeowners, working with NMD90/Romex cable requires an ESA permit and licensed electrician. While you can legally replace outlets and switches with the power off, running new circuits or extending existing ones falls under permit-required work. This isn't just about code compliance - improper installation can cause house fires, electrocution, or insurance claim denials.

If you're planning electrical work involving new circuits or rewiring, contact a licensed electrician who can pull the proper ESA permits and ensure code-compliant installation. For existing NMD90 cable showing signs of damage, overheating, or age-related deterioration, have it inspected professionally rather than attempting repairs yourself.