How to Change a Single-Pole Light Switch?

Replacing a single-pole light switch is one of the simplest electrical jobs an Ontario homeowner can do safely, provided you follow the right order and know when to stop. This guide walks GTA homeowners through how to change a single-pole light switch step by step, what tools you need, what the Ontario Electrical Safety Code and the ESA say about the work, and the warning signs that mean you should book a licensed electrician instead.

How to Change a Single-Pole Light Switch in an Ontario Home

Direct answer: turn off the breaker feeding the switch, verify the wires are dead with a non-contact voltage tester, unscrew the switch, note which conductor is on which terminal, move the two hot conductors (line and load) to the same two terminals on the new switch, land the bare copper bond on the green ground screw, screw the new switch back into the box, and restore power. From breaker off to breaker on, the job takes 10 to 15 minutes.

Tools and a code-compliant replacement switch

Direct answer: use a 15-amp residential single-pole switch that is CSA-approved and matches the amperage of the circuit. Do not upgrade a switch from 15 A to 20 A on a 15 A circuit — the rating is about the wire, not the switch, and mismatching them violates Section 14 of the Ontario Electrical Safety Code.

• Replacement single-pole switch (CSA-marked, 15 A / 120 V for standard residential lighting)
• Non-contact voltage tester (a $15 pen-style tester is enough)
• Insulated flat and Phillips screwdrivers
• Needle-nose pliers for shaping conductor hooks
• Painter’s tape and a phone camera for labeling the wires before disconnect

Step-by-step: change a single-pole switch

1. Kill the breaker. Turn off the breaker feeding the circuit at the panel. Flip the switch — the light should not respond. Then, at the switch itself, hold a non-contact tester against each conductor. If any conductor beeps, the wrong breaker is off.
2. Remove the wall plate and the switch. Two screws hold the plate. Two more hold the switch strap to the box. Loosen them and gently pull the switch straight out. Do not yank on the conductors.
3. Photograph the wiring. Take a clear photo showing which conductor lands on which terminal, including the ground. This is your safety net if you get interrupted mid-job.
4. Note the two hot terminals. A single-pole switch has two brass terminals and one green ground terminal. The two brass terminals are electrically interchangeable — which conductor lands on which of the two does not matter.
5. Disconnect the conductors. Loosen the two brass terminal screws and remove both hot conductors. Loosen the green screw and remove the bare copper bond.
6. Prep the new switch. If the conductors are worn or nicked, snip 1 cm off the end and re-strip to fresh copper. Bend a small hook that wraps clockwise around each screw.
7. Land the wires. Wrap each hot conductor around one of the brass screws, tighten firmly, and check with a gentle tug — no wiggle allowed. Land the bare bond on the green screw the same way.
8. Fold and reinstall. Push the conductors carefully back into the box, secure the switch strap with the two mounting screws, and reinstall the wall plate.
9. Restore power and test. Turn the breaker back on. The switch should turn the light on and off cleanly, with no buzz or delay.

When to stop and call an electrician

Direct answer: stop the job and call a licensed electrician if the box contains aluminum conductors, cloth-insulated conductors from before 1965, more than two hot conductors on the switch, evidence of overheating (browned insulation, melted terminal), or if the box has no equipment bond.

The Electrical Safety Authority lists aluminum branch-circuit wiring as a persistent residential fire risk in its Ontario Electrical Safety Report and requires special CO/ALR-rated devices for any aluminum connection. Standard hardware-store switches are not CO/ALR-rated. If you find aluminum, do not touch it — call a contractor.

If you are unsure whether the job is within homeowner territory, our post on replacing a light switch yourself covers the boundary questions in detail.

Ontario permits: what you need to know

Direct answer: a like-for-like single-pole switch swap is maintenance and does not require an ESA Homeowner Wiring Notification. Anything beyond that — running new cable, adding a switch location, or converting to a 3-way — does. Homeowners doing new wiring must file the notification with ESA before energizing the circuit.

For a 3-way conversion, our step-by-step 3-way wiring guide covers the extra conductor and terminal changes. If you have three or more switch locations, our 4-way switch explainer completes the picture.

Expert tip from our ESA-licensed electricians

In our experience swapping thousands of switches in GTA homes over the years, the one detail homeowners skip that costs them the most time is checking the bond conductor. About one in ten Toronto houses built between 1955 and 1975 has a switch box with no bond wire at all, which was code-legal at the time but is not now. If you see no bare copper, do not just move on — the box needs a proper bond added, which pulls the job out of homeowner territory. We add a bond and a plastic yoke to keep the swap safe. Homeowners who wire a new switch into an unbonded box create a real shock hazard the next time the fixture faults to the metal strap.

Related reading from ezsmart.ca

• Can I Replace a Light Switch Myself?
• How Do You Wire a 3-Way Light Switch?
• What Is a 4-Way Switch and How Does It Work?
• How to fix a light switch that will not click
• Why is my light switch warm to the touch?

Contact us

Not sure whether the switch box in your home is safe to work on yourself? Book an ESA-certified electrician to make the swap and inspect the circuit. Call us at 416-838-9006 or visit our contact page — we will get back to you the same day.