How do you wire a single pole light switch?

Connect the supply hot to one brass screw and the hot going to the light to the other brass screw. Splice the white neutrals together without touching the switch, and join the grounds with a pigtail to the green screw. The two brass screws of a plain single pole switch are normally interchangeable.

Which wire goes on which screw of a single pole switch?

On a plain single pole switch it normally does not matter. The switch only opens and closes the circuit, so either brass screw can take the wire from the panel and the other the wire to the light. If your switch marks its screws, follow the marks. The ground wire goes on the green screw.

Does a light switch need a neutral wire?

A plain single pole switch does not use the neutral. The neutral is spliced through the box or stays in the light box and is never connected to the switch. Smart switches and many dimmers do need it, and the code asks for a neutral at many lighting switch locations in new work (NEC 404.2(C), with exceptions).

What is a switch loop and how is it wired?

A switch loop is a layout where the power arrives at the light and a 14/2 cable runs from the light box to the switch. The black hot is spliced to the white of that cable in the light box, the white is re-marked black at both ends and goes to one brass screw, and a black conductor from the other brass screw returns to the fixture. The second diagram shows it.

Why is a white wire connected to the switch in a switch loop?

The cable to the switch has only two insulated conductors, so the white one carries the supply. It must be re-marked black or another color at each end, and it may only be the supply to the switch, never the return to the light. Check the NEC edition your area has adopted.

How do I wire two switches to one light?

Use two 3-way switches instead of single pole switches. They have a common screw and two traveler screws. See the Three Way Switch Wiring Diagram Generator linked on this page.

Can I rely on an AI-generated light switch diagram?

No. Treat it as a picture. Image models often draw wrong connections, for example a neutral on the switch. Check every AI picture against the exact diagrams on this page.

Is the light switch wiring diagram generator free?

Reading the exact diagrams and the table on this page is free. The AI illustration tool starts free with 2 image credits, valid for 7 days, no card required. Image credit packs start at $4.99 (Lite, 8 image credits), and the credits do not expire.

Engineering Tool

Light Switch Wiring Diagram Generator for a Single Pole Switch

Exact single pole light switch wiring diagrams: power at the switch or at the light (switch loop), with a connection table. Planning drawings only.

Exact diagrams: power at the switch and a switch loopHot switched, neutral and ground never mixed upConnection table built from the same list the checker usesAI illustration tool for your own lighting circuit

Planning diagrams, not code advice. Turn the breaker off and test for voltage before you open a box. Planning diagram; follow local code and the device instructions; a licensed electrician decides what gets installed.

Need two switches for one light? That takes two 3-way switches: see the Three Way Switch Wiring Diagram Generator.

Single Pole Light Switch Wiring Diagrams

Exact diagrams drawn in code from a connection list checked against public sources (switch maker instructions, NEC text). Each shows the supply, the switch with its two brass screws, the light, the neutral, the ground and the cable runs. One light, one switch, 120 V.

Exact wiring diagram of a 120 V single pole light switch: breaker hot to one brass screw of the switch, the other brass screw to the brass screw of the light, neutral spliced through the switch box to the light, ground chained to the switch and the light — Power at the switch box, light at the end of the run
The supply cable enters the switch box. The black hot goes to one brass screw of the switch. The other brass screw sends the switched hot to the light in a second cable. The white neutral is spliced through the switch box and goes straight to the light. The grounds are joined and a pigtail goes to the green screw.
Cable runs: 14/2 from the panel to the switch box, 14/2 from the switch box to the light.
Known simplification: the neutral is drawn as one wire from the panel to the light. In the switch box it is a wire-nut splice between two white conductors. In the boxes, grounds are joined with a pigtail rather than chained through device screws. The switch is drawn closed (light on).

Exact wiring diagram of a 120 V single pole switch loop: supply hot spliced in the light box to a white conductor re-marked black that runs to one brass screw of the switch, a black conductor from the other brass screw back to the light, neutral only in the light box — Power at the light: a switch loop
The supply cable enters the light box. The black hot is spliced there to the white conductor of the 14/2 cable to the switch. That white is re-marked black at both ends and carries the supply only. It lands on one brass screw of the switch. The black conductor from the other brass screw comes back to the fixture hot. The neutral stays in the light box.
Cable runs: 14/2 from the panel to the light box, 14/2 from the light box to the switch (white re-marked black, black, bare).
Known simplification: the neutral is drawn as one wire from the panel to the light box, and the re-marked white is drawn with black bands. In the boxes, grounds are joined with a pigtail rather than chained through device screws. This layout has no neutral in the switch box. New work in many areas needs a neutral at lighting switch locations (NEC 404.2(C), with exceptions), so check whether this layout is allowed for new work where you live.

Connection Table: Hot, Switched Hot, Neutral, Ground

The same connections as the diagrams. Every terminal appears once. On a plain single pole switch the two brass screws can be swapped with each other; marks printed on the device win.

Layout	Connected together
power at the switch box	Supply hot + Switch brass screw on the supply side Switch brass screw on the light side + Light hot Supply neutral + Light neutral Supply ground + Switch ground screw + Light ground
power at the light (switch loop, white re-marked as the supply)	Supply hot + Switch brass screw on the supply side Switch brass screw on the light side + Light hot Supply neutral + Light neutral Supply ground + Switch ground screw + Light ground

Colors are insulation colors in NM cable, not phases. In the switch loop the supply reaches the switch on a white conductor re-marked black at both ends, and the black conductor is the return to the light.

This page covers one light and one switch. For two switch locations, see the Three Way Switch Wiring Diagram Generator. For other wiring, such as home, automotive, or appliance systems, use the Wiring Diagram Maker.

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Exact wiring diagram of a 120 V single pole switch: hot to one brass screw, the other brass screw to the light, neutral to the light only

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AI diagrams are drafts. Check every screw, the neutral and the ground against the exact diagrams.

Sources (checked October 2026): Purdue Extension 4-H, Wiring Diagrams for 3-Way and 4-Way Switch Combinations (for multi-way switches), NFPA, NEC Code-Making Panel 5 draft (200.7(C)(1), numbered 200.8(C)(1) in the 2026 draft), Mike Holt, Switches, based on the 2020 NEC (404.2(A) and (B); a training reference, not the code text), and HomeTips, Standard light switch wiring for the terminal layout of a single pole switch.

What a light switch wiring diagram shows

A light switch wiring diagram shows how one switch turns one light on and off. The switch is a single pole switch: it opens and closes one conductor, the hot. Everything else is routing: where the cable from the panel arrives, which conductor reaches which screw, and where the neutral and the ground go. This page draws the two common layouts as exact diagrams from a documented connection list checked against public sources (switch maker instructions, NEC text) and puts the same connections in a table.

Power at the switch or power at the light

Open the boxes and find where the cable from the panel arrives. If it arrives in the switch box, use the first diagram. If it arrives in the light box and a single cable runs from there to the switch, you have a switch loop: use the second.
Not covered on this page: several lights on one switch, a switch and an outlet in the same box, 3-way and 4-way circuits, and smart switches. Use the Wiring Diagram Maker linked below for a rough draft of those, and have the layout checked.

Need two switches for one light?

A single pole switch controls a light from one place. To control the same light from two places you need two 3-way switches, which have a common screw and two traveler screws. The Three Way Switch Wiring Diagram Generator linked below draws that circuit, including the power at the light layout.

The switch only breaks the hot

On a plain single pole switch the two brass screws are normally interchangeable (if the device marks them, its marks win). One takes the hot from the panel and the other sends the hot on to the light. A single pole switch breaks only the hot conductor, as the switch maker instructions show, and the code says the same for 3-way and 4-way switches (NEC 404.2(A)). Separately, NEC 404.2(B) says a switch may not disconnect the grounded (neutral) conductor of a circuit, with narrow exceptions. So the white neutral never lands on the switch.
A checker compares each drawing on this page with the reference layout and rejects a drawing with the neutral on the switch, a supply that skips the switch, or a missing ground.

The white wire that is not a neutral

In a switch loop the supply has to travel to the switch on the white conductor of the 14/2 cable, because the cable has no other conductor to spare. NEC 200.7(C)(1) (2017 to 2023 numbering; the 2026 draft renumbers it 200.8(C)(1)) allows a white conductor in a cable to be used as a hot only if it is permanently re-identified at each termination and wherever it is visible and accessible. For single-pole, 3-way and 4-way switch loops the re-identified conductor may be used only for the supply to the switch, not as the return conductor from the switch to the outlet. The quoted wording is from NFPA's Code-Making Panel 5 draft for the 2026 NEC; check the edition your area has adopted.
In the diagram the re-marked white carries only the supply to the switch, and the black conductor is the return to the light. Using the white as the return is the mistake the checker rejects.

Neutral at the switch box

Since the 2011 edition the code asks for a neutral at many lighting switch locations (NEC 404.2(C)), with exceptions. The first diagram has one, spliced through the box. The switch loop diagram does not, which matters for smart switches and for new work. Ask your local inspector or a licensed electrician what applies where you live.

Replacing a switch with a dimmer

A basic single pole dimmer replaces a single pole switch and takes the same two hot connections, usually as two leads plus a ground. Many smart dimmers and timers also need the neutral in the box, so check the instructions before you buy one for a switch loop, where the box has no neutral.
Dimmers have load ratings and bulb type limits. The instructions printed on the dimmer decide, and this page draws plain switches only.

Troubleshooting a single pole switch

The light never turns on: the supply is not on one brass screw, the light wire is not on the other, or a splice is loose. In a switch loop, check that the re-marked white is spliced to the supply hot in the light box.
The light is always on, or the switch does nothing: the hot bypasses the switch, for example the supply spliced straight to the light hot.
The breaker trips when you turn the power on: a hot touches a neutral or a ground. Turn the power off and check every splice.

Before you open a box

Turn the breaker off and test every wire for voltage. A switch box can hold wires from another circuit.
Check how the boxes are wired before you copy a diagram. Many existing circuits do not match a textbook layout.
The diagrams show 14 AWG cable on a 15 A breaker. Use 12 AWG cable on a 20 A circuit, and match the cable, breaker and switch rating together.

Exact diagrams vs AI drafts

The two diagrams above are exact reference diagrams. They are drawn in code from a documented connection list, and a checker compares each drawing with a reference table. We do not show AI-generated wiring images as examples, because image models often draw wrong connections, such as a switched neutral. The generator on this page still produces an AI illustration from your prompt. Treat it as a rough picture, compare it with the exact diagrams, and let a licensed electrician decide what gets installed. A diagram from this page is a planning picture, not a permit drawing, and it does not replace the device instructions or the electrical code that applies in your area.