EZSMART Corporation, ESA/ECRA #7012690 , North York , Ontario
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Open any electrical box in a Canadian home and you see the same colour palette — black, white, red, green, and bare copper. Each colour carries a specific meaning under the Ontario Electrical Safety Code, and mixing them up is the fastest way to create a shock hazard or a code violation. This guide walks GTA homeowners through the colour code for house wiring, what each colour signifies in Canadian residential installations, and where the code allows re-marking for special cases.
Direct answer: in Canadian residential wiring following the Ontario Electrical Safety Code, black is the primary hot conductor, white is neutral (grounded conductor), red is a second hot in 14/3 or 12/3 cable, green is an insulated equipment bond, and bare copper is a non-insulated equipment bond. These colours are consistent across NMD-90 cable used throughout Ontario.
Direct answer: in some legacy switch-loop configurations, the white conductor in a 14/2 cable functioned as a switched hot from the ceiling box down to the switch. The Ontario Electrical Safety Code allows this only if the white conductor is re-marked at both ends with black tape or black paint (three inch minimum wrap) to visually identify it as a hot.
Modern installations use 14/3 cable to avoid the white-as-hot issue. Older homes may still have this configuration — respect the re-marking convention and do not assume white is neutral if it is on a hot terminal.
Direct answer: US NEC and Canadian OESC largely agree on residential 120 V colours (black, white, green, bare). Differences appear in commercial and industrial three-phase installations, where colour codes can vary by jurisdiction. Residential DIY in Ontario follows the Canadian standard consistently.
Our post on Romex vs THHN vs UF covers cable types where different colour conventions can appear.
Direct answer: if you open a box and find conductors that do not match the standard code (all-white, all-black, or unusual combinations like yellow or blue), stop and consult a licensed electrician. Old installations, DIY modifications, or non-Canadian cable can create confusing conditions where the code no longer applies at face value.
The Electrical Safety Authority notes that miswired devices from incorrect colour assumptions are among the top homeowner-caused writeups on residential inspections. When in doubt, use a multimeter to verify voltage before touching anything.
In our experience diagnosing GTA wiring across all vintages of Ontario homes, the single most common colour-related mistake is assuming white is always neutral. In 14/2 switch loops installed before about 2000, the white conductor between the ceiling box and the wall switch is a switched hot. If the previous owner did not re-mark it with black tape, the next homeowner opens the box and assumes the white is safe to touch. Our rule: verify every conductor with a multimeter before terminating, regardless of colour. Colours are a guide, not a guarantee. Our post on multimeter use covers the verification technique.
Found unusual colours in a GTA electrical box and unsure how to interpret them? Book an ESA-certified electrician. Call us at 416-838-9006 or visit our contact page — we will get back to you the same day.
Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp
