What type of wire is used for residential electrical?

Residential electrical systems in Canada primarily use copper wire with thermoplastic insulation, specifically NMD90 (Non-Metallic Dry, 90°C rated) cable for most interior applications.

The most common residential wire type is Romex-style NMD90 cable, which consists of insulated copper conductors bundled together with a plastic outer sheath. This cable contains a hot wire (black), neutral wire (white), and ground wire (bare copper or green), all wrapped in a protective outer jacket. The "90" designation means it's rated for 90°C operating temperature, making it suitable for modern electrical loads.

Wire gauge depends on the circuit amperage and application. For standard 15-amp circuits (most outlets and lights), 14 AWG copper wire is used. For 20-amp circuits (kitchen counters, bathrooms, some appliances), 12 AWG copper wire is required. Larger appliances need heavier wire - electric dryers typically use 10 AWG for 30-amp circuits, while electric ranges may require 6 AWG or larger for 40-50 amp circuits.

Specialized applications require different wire types. For wet locations like bathrooms or outdoor installations, NMWU (wet location) cable or individual THWN conductors in conduit are used. Underground installations require direct burial cable or conduit-protected wiring. Panel-to-panel connections often use TECK cable (armored cable) for added protection.

Older homes may have different wiring types that are no longer installed. Knob and tube wiring (pre-1950s) used individual cloth-wrapped wires, while aluminum wiring was briefly used in the 1960s-70s. Both present safety concerns and may need updating to meet current Ontario Electrical Safety Code requirements and insurance standards.

All residential wiring must meet ESA standards and be installed by licensed electricians for most applications. Wire selection depends on your specific circuit requirements, local conditions, and code compliance - factors that require professional assessment for safety and legal compliance.