How to Wire a Light Switch
Power off, test it, then connect line, load and ground.
By Jonathan West · reviewed 2026-10-11 ·how we research these
To wire a light switch, turn off the circuit breaker or fuse and test that the power is off. Connect the line hot and the load to the switch's two terminals, connect the ground to the green screw, then mount the switch and restore power. In the single-pole diagram on the Leviton Cat. No. 5601 instruction sheet, the white neutral conductors form a separate connection that never lands on the switch terminals.
The steps below use the Leviton 5601 as their example. It is a single-pole switch rated 15 amps (A) at 120/277 volts alternating current (AC). The instruction sheet packed with your own switch governs your job, because terminal layout, wire gauge limits and torque figures differ from model to model.
How to Wire a Light Switch in Six Steps
Wiring a single-pole light switch takes six steps, starting with the power and ending with a test at the switch. The strip lengths and torque figures come from the Leviton sheet.
- Turn off the circuit breaker or fuse that feeds the switch, then test that the power is off.
- Identify the line hot, load, neutral and ground conductors in the box.
- Strip each conductor to the length shown on the strip gauge on the switch.
- Connect the line hot and the load to the two switch terminals, and the ground to the green screw.
- Fasten the switch with the long mounting screws and attach the wallplate.
- Restore power at the breaker or fuse and test the switch.
The Leviton sheet warns that to avoid fire, shock or death, you must turn off power at the circuit breaker or fuse and test that the power is off before wiring.
Turning Off and Testing the Power First
Shock is only one of the hazards the sheet names, and its warning lists fire first. The U.S. Fire Administration (USFA) estimates that in 2021, about 24,200 residential building electrical fires were reported to US fire departments.
USFA puts the toll of those fires at an estimated 295 deaths, 900 injuries and over $1.2 billion in property loss. Turn off the breaker or remove the fuse, then test that the power is off.
Gather everything on the list below before you open the box, so you are not working with a half-wired switch while you look for a tool.
- The new switch and the instruction sheet packed with it.
- A wallplate, which the Leviton sheet says is not included with the switch.
- A voltage tester or multimeter.
- A wire stripper.
- A screwdriver for the terminal and mounting screws, plus a small screwdriver for releasing a push-in connection.
Identifying the Wires in the Switch Box
The Leviton single-pole diagram shows four kinds of conductor in a switch box: line hot, load, neutral and ground. The line hot (black) and the load (black) go to the two switch terminals. The neutral (white) conductors are a separate connection that does not land on the switch terminals, and the ground goes to the green screw.
If you cannot tell which black conductor is line and which is load, do not guess. The diagram on your own switch's instruction sheet shows which terminal takes each one, so you need to know both before you reconnect anything.
Our wire color code page covers what each common conductor color means.
Connecting the Wires
The Leviton 5601 accepts conductors three ways: push-in Quickwire holes, backwire clamps under the terminal screws, and side wire loops around the terminal screws. Quickwire holes take #14 American Wire Gauge (AWG) solid copper only. Strip about 5/8 inch (1.6 cm) per the strip gauge, push the straight wire into the round hole, and to release it, press a small screwdriver tip into the release slot and back the wire out gradually.
For backwire, strip about 5/8 inch, slide the straight wire under the clamp and tighten the screw to 14 to 18 in-lbs (1.6 to 2.0 newton-meters, N·m). For side wire, strip about 3/4 inch (1.9 cm), loop the wire clockwise three-quarters of a turn around the screw, and tighten it over the loop to the same 14 to 18 in-lbs.
Connect the ground to the green screw. You can loop it with the side wire method, or slide the straight wire between the screw head and the tab and into the hole, then tighten the screw firmly over it.
The push-in holes take #14 solid copper only, while the screws take #10, #12 and #14 copper.
| Method | Strip Length | Wire Accepted | How It Is Secured |
|---|---|---|---|
| Quickwire (push-in) | About 5/8 in (1.6 cm) | #14 AWG solid copper only | Push straight wire into the round hole. Release with a small screwdriver in the release slot. |
| Backwire | About 5/8 in (1.6 cm) | #10, #12 and #14 AWG copper, or #10 and #12 copper clad | Straight wire under the screw clamp, tightened to 14 to 18 in-lbs (1.6 to 2.0 N·m). |
| Side wire | About 3/4 in (1.9 cm) | #10, #12 and #14 AWG copper, or #10 and #12 copper clad | Loop clockwise 3/4 turn around the screw, tightened to 14 to 18 in-lbs. |
| Ground (green screw) | Not published | Ground conductor | Side wire loop, or straight wire between screw head and tab, screw tightened firmly. |
Mounting the Switch and Restoring Power
Mounting the switch comes after every conductor is connected and tight. Fasten the switch with the long mounting screws, and attach the wallplate. Buy the wallplate separately, since the Leviton sheet says it is not included with the switch.
Some switches carry a self-grounding clip. The Leviton sheet says that clip gives an automatic ground connection only in a properly grounded metal wallbox. Do not count on the clip for your ground unless the box is metal and properly grounded, and connect the ground conductor to the green screw.
Restore power at the circuit breaker or fuse. If the switch does nothing, the breaker trips, or anything smells hot, turn the breaker off again and go to the stop list below.
Wire Gauge and What the Switch Accepts
The Leviton 5601 is rated 15 A at 120/277 V AC, and its terminals limit which wire you can attach. The sheet says to use the switch with copper or copper clad wire only.
Push-in holes take #14 AWG solid copper only. For a circuit wired with #12 AWG solid copper or copper clad wire, the sheet directs you to the terminal screws instead. The back and side wire screws accept #10, #12 and #14 AWG copper, or #10 and #12 copper clad wire.
When the Switch Does Not Work and When to Call an Electrician
Five findings during or after a light switch job mean you stop work and call a licensed electrician.
- The switch does nothing after you wire it.
- The breaker trips when you restore power.
- You smell burning, the wallplate feels warm, or a wire looks discolored.
- The box holds scorched insulation.
- The box holds aluminum wire. The Leviton sheet allows copper or copper clad wire only.
Stop work if you smell burning or find a warm wallplate. Call a licensed electrician.
Who Should Not Wire This Switch Themselves
A box with aluminum wire or scorched insulation is not a DIY job. In any of those cases, hire a licensed electrician rather than reconnecting by guesswork.
If your switch's instruction sheet shows a different terminal layout, strip length or torque than the Leviton figures above, follow your sheet. A breaker that trips after wiring is also on the stop list above. Our page on a circuit breaker that keeps tripping covers that symptom, but on a switch you just wired, the fix belongs with an electrician.
Wiring a Light Switch vs a 3-Way or Dimmer Switch
A single-pole switch on the Leviton diagram has two brass-colored switch terminals plus a green ground screw. A 3-way switch uses a different layout. The same Leviton sheet shows a common terminal with a black screw and two traveler terminals with brass screws, and our 3-way switch wiring page covers that job.
A dimmer comes with its own instruction sheet, and that sheet governs the job. Follow the diagram, strip length and torque on the dimmer's sheet.
Wiring a switch and an outlet together, or switches in series, falls outside the Leviton single-pole diagram. For those jobs, follow the diagram on your device's own instruction sheet, or hire a licensed electrician.
Common questions
How do I wire a light switch with 2 wires?
The number of wires in a switch box depends on how that box was wired, so do not guess from a count alone. Identify each conductor as line hot, load, neutral or ground before you connect anything. If you cannot identify every conductor, call a licensed electrician.
Do I need to connect the ground wire to a light switch?
Yes, connect the ground to the green screw on the switch, as the Leviton diagram shows. A self-grounding clip gives an automatic ground only in a properly grounded metal wallbox.
Which wire goes to which terminal on a single-pole switch?
The line hot and the load connect to the two switch terminals, the ground goes to the green screw, and the white neutrals form a separate connection that does not land on the switch terminals. The diagram on your own switch's instruction sheet shows which terminal takes line and which takes load.
Can I use the push-in holes with 12-gauge wire?
No. The Leviton sheet says the Quickwire push-in holes accept #14 AWG solid copper only, and it directs #12 AWG circuits to the terminal screws.
How do I wire a dimmer switch?
Follow the instruction sheet packed with the dimmer. The Leviton 5601 strip lengths and torque figures apply to that single-pole switch, and the dimmer's own sheet governs.
How tight should light switch terminal screws be?
The Leviton 5601 sheet gives 14 to 18 in-lbs (1.6 to 2.0 N·m) for the backwire and side wire terminal screws. Tighten each screw to 14 to 18 in-lbs, as the sheet directs. Then mount the switch, attach the wallplate and restore power at the breaker.