How to Wire a Light Switch

By |Last updated on |Closet, Lights and Switches|6 Comments

This project shows how to wire a light switch after the switch box wiring rough-in in this phase of How To Build a Basement Closet. The closet ceiling light was wired in the prior installment.

How to Wire a Light Switch

The new basement closet wiring has been roughed-in for the wall outlet power extension to the closet ceiling light. I’m now making the wiring connections working my way from top to bottom:

  • wire the ceiling light fixture
  • wire the wall light switch
  • connect the Wiremold surface mount junction box
  • lastly, connect the light circuit to the wall outlet for power

Because the NM-B 14/2 line-side (bottom cable) is not yet connected to the wall outlet, the wires are dead (no electricity) and are safe to work on.

If you happen to be replacing an existing light switch, shutoff the electricity at the circuit breaker panel and verify the power is Off with a voltage detector before working with the wiring. Hire a licensed electrician if you have any doubts.

Rough-in Wiring Preparation

In the next photo, the NM-B 14/2 cable entering the bottom of steel switch box is the “line-side” that will carry power from the wall outlet. The NM-B 14/2 cable leaving the top of the switch box is the “load side” that goes to the ceiling light.

The Leviton 5501-LHI heavy duty grounding illuminated-off toggle switch will operate the closet ceiling light. I like illuminated light switches in certain locations because it saves hunting around in the dark. The proper name for this common style of light switch is a “toggle switch”. One minor issue with the Leviton commercial grade 5501-LHI switch is it clicks a bit loudly when flipping the switch, whereas most residential light switches operate quietly.

Prepare the roughed-in NM-B 14/2 cables by doing the following:

  • The outer jacket of the NM-B 14/2 cables are carefully removed so as not to damage the insulation on the individual wires.
    Make a short, shallow lengthwise cut in the outer jacket at the end of the cable, then peel the outer jacket back like a banana.
  • Leave 1 inch of of the outer insulation jacket poking inside switch box as shown.
  • Tighten the cable clamp screws in the switch box to secure the NM-B 14/2 cables.
  • Trim the wires if needed to have at least 6 inches of wire extending beyond the switch box.
  • Strip approx. 5/8 inch of insulation from the ends of the black (hot) and white (neutral) wires with wire strippers.
Light Switch Wiring: Leviton Grounding Light Switch

Light Switch Wiring: Leviton Grounding Light Switch

Light Switch Ground & Neutral Wiring Connections

Ground wire (bare copper) connections:

  • Cut a 6 inch length of 14 gauge copper wire to make a pigtail connection to the light switch.
  • Make a small loop in the end of the pigtail ground wire and place the loop around the green ground screw on the light switch.
  • Pinch the loop closed with needle nose pliers.
  • Tighten the ground screw.
  • Right-twist (clockwise) the ends of the three ground wires together with the linesman pliers and secure with a wire nut.

White (neutral) wiring connections:

  • Strip about 5/8 inch of insulation from the white neutral wires.
  • Twist the white wires together and secure with a wire nut.
Light Switch Wiring: Ground Wire Connections

Light Switch Wiring: Ground Wire Connections

Light Switch Hot (Black) Wiring

The Leviton toggle switch is side wired. Take care to orient the light switch correctly… the toggle lever will display the word “On” when the switch is upright and in the On position. The line-side (from the circuit breaker) black wire from the bottom of the switch box is connected to the bottom side screw as shown in the next photo.

  • Make a small loop in both black (hot) wires.
  • Connect the line-side black wire to the lower switch side screw.
  • Pinch the loop closed around the correct side screw on the switch.
  • Firmly tighten the screw.
Light Switch Wiring Connections: Neutral and Ground Wires

Light Switch Wiring Connections: Neutral and Ground Wires

  • Loop the load-side (to the closet light) black wire around the upper side screw, pinch the loop closed with needle nose pliers, then tighten the screw. (I’ve yet to tighten the upper side screw in the next photo to illustrate the wire loop.)
Leviton Grounding Toggle Swtich Wiring: Black (Hot) Wires

Leviton Grounding Toggle Swtich Wiring: Black (Hot) Wires

The finished light switch wiring connections:

Toggle Switch NM-B 14/2 Wiring Connections

Toggle Switch NM-B 14/2 Wiring Connections

Drywall Installation

If you’re wondering why I installed the light switch before the drywall, the reasons are:

  • I’m leaving this part of the wall and electrical wiring open while waiting for the building inspector to arrive and sign-off on my work.
  • The light switch will be slipped through the drywall cutout for the switch box when I hang the drywall, so this is not a concern.
  • I want to complete the wiring connections so the closet light is operational to better see when finishing the drywall inside the closet.

But what about the exposed side screws on the light switch? Wouldn’t that be a shock/electrocution hazard if the electricity is turned on before mounting the light switch in the steel switch box? It sure would be! To avoid being accidentally shocked, I temporarily wrapped the toggle switch with several layers of 3M vinyl electrical tape rated for 600 volts.

Light Switch Temporarily Insulated with Electrical Tape

Light Switch Temporarily Insulated with Electrical Tape

Since I don’t have young children or other susceptible persons in the house, doing so isn’t a major concern. I informed the family of the hazard with orders to stay out of the construction site and to keep the basement bedroom door closed.

I’m not recommending that you do this; instead you should fold the wires into the switch box and mount the toggle switch to the box. The switch plate can be temporarily installed if you’re worried about children sticking their fingers in the switch box.

The Wiremold® junction box and outlet box wiring connections are completed to power up the closet light in the next part of this series.

Take care,

Bob Jackson

Copyright © 2018   Reproduction strictly prohibited.


  1. Roquet May 29, 2017 at 1:21 pm - Reply

    I though lights needed to be connected to both neutral(white) and hot (black)? If the switch is illuminated wouldn’t it need to have a neutral connection?

    • Bob Jackson May 29, 2017 at 2:52 pm - Reply

      See What is the difference between an illuminated switch and a pilot light switch? because an “illuminated On” is wired differently from a “pilot light Off”.

      Residential grade toggle switches with a pilot light Off feature for finding a switch in the dark don’t require a neutral connection. For example, the Leviton 5501-LHW illuminated Off single pole light switch. See the Support section on the product page for the wiring diagram. The LED or neon pilot light operates by running a very small trickle current through the load to complete the circuit. The “load” is whatever the switch is controlling such as an overhead light bulb, ceiling fan, etc.

      Illuminated On switches are typically found in industrial situations do require a neutral connection, e.g. the Leviton 1201-PLC and it’s wiring diagram which requires a neutral wire connection.

      Always follow the manufacturer wiring instructions to be safe.

  2. Lorian Bartle April 13, 2018 at 5:59 pm - Reply

    A lot of switches today allow wires to be pushed into a hole in the back. I certainly prefer to do that, when permitted, over forming the wire into a hook.

    Lorian Bartle

  3. Candace Baker December 1, 2018 at 1:49 pm - Reply

    I only have one Romex ran from my fixture to the light switch box. So should I pigtail the black wire and connect it to both screws on the switch? Or do I just connect it on one end? I’m so confused. Or should I install an outlet below the switch so I have two black wires to connect to the toggle switch?

    • Bob Jackson December 1, 2018 at 4:12 pm - Reply

      Did you install the Romex electrical cable? How many wires (conductors) and what colors are in the cable?

      NM-B 14/2 cable has three wires: Black (hot), White (neutral) and bare copper (ground). The bare copper wire is normally wrapped in a brown paper sheath.

      NM-B 14/3 cable has four wires: Black (hot), White (neutral), red (hot) and bare copper (ground).

      I suspect you have NM-B 14/2 cable going to the light switch. A single-pole light switch simply makes/breaks continuity in the hot side of the circuit to the light fixture. My basement closet light switch electrical box has two NM-B 14/2 cables per the wiring diagram because it’s new construction and the switch is inline with the cable run to the fixture.

      Your dilemma you only have a single NM-B cable, let’s assume it’s NM-B 14/2 with black, neutral and ground wires. The light switch would be wired by “recoding” the neutral wire as hot. I wired a new light switch this way when I remodeled my basement bathroom. Focus on the light switch in the center of this diagram for the solution. Details are in How to Finish a Basement Bathroom – wiring the ceiling junction box, vanity light and GFCI wall outlet with wiring diagrams.

      If your NM-B 14/2 cable is wired as expected, power from the circuit breaker panel feeds the black wire. If so, the black wire is the “line side” of the circuit. Verify the black wire is the line side with a voltage detector with the wires disconnected, and there is no voltage on the white/neutral wire. Be careful and don’t touch anything.

      After verifying the black wire is the line side, recode (i.e. flag) the white wire as hot by wrapping a piece of black or red electrician’s tape around it, or coloring the white wire black with a permanent marker. Recoding simply let’s someone know the neutral wire has been repurposed as a hot wire. The recoded white wire will be on the “load side” of the circuit. Recoding is common practice for light switches. Connect the black (hot) wire to bottom terminal of the light switch, and the recoded white wire to the other switch terminal. This should conform the switch manufacturer’s wiring instructions.

      You can send photos to bob[at] for additional help. Replace the [at] with the @ symbol.

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