How To Change A 3 Way Light Switch

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A iii-style low-cal switch allows you to control a calorie-free source from ii separate points.^[1] Although a three fashion is one of the hardest electrical circuits to figure out, it'south as well 1 of the about useful.

Notation: there are several ways to install a 3 Manner Light Switch. The methods shown hither are some of the safest and most versatile, though non the but options.

1. 

   i

   Flip off ability in the room y'all're working. ^[2] Head to your fuse box and brand sure there is no power coming to the room y'all're currently working in. Utilise a voltage detector to ensure that y'all're non going to shock yourself once you first working.

2. 

   2

   Spiral your two boxes and light fixture into place, and then assemble your supplies. Before you even start wiring, you want to get the fixtures securely in place so that y'all tin can effectively wire everything together. You will need:

   • Two 3-Way Switches
   • Two two-wire non-metallic (NM) cablevision
   • One 3-wire NM cables
   • 2 half dozen" pieces of grounding wire

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   Slide the 2-wire NM power cable into the first switch box. Take your power wire, coming from the house, and slide it into the first switch box. Cull a management that will brand information technology easy for you to so thread the wire towards your second switch box.

4. 

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   Remove nearly 9 inches of sheathing from the wire. Strip off enough of the safe coating around your NM wire to betrayal the wires underneath. Some people prefer to do this before feeding into the switch box, just it doesn't matter.

   • You lot desire roughly 3" of wire in the box, and 6" exterior the box.

5. 

   v

   Run a iii-wire NM cable between the first and second boxes. Strip 6-9" on i end to expose the 3 separate wires, then run the first half into your first switch box. Repeat on the other end and run it into your second switch box. Cut the cable to length if there is extra once you pull through the second box.

   • This 3rd wire allows ability to run to your 2nd switch even if the first i is off.

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   half dozen

   Use a cable staple to secure the wires to the wall or stud inside viii" of the box. Cables must be secured so that, if there is tugging or pulling farther downwardly the line, the alive wires don't rip out of the box and cause issues. Some boxes have clamps to hold onto the wires. Electric current electrical codes require whatsoever switch box without built-in clamps to accept the wires secured inside eight inches of the box.

   • Secure to the middle of the stud, in the wall, so that it will not be hit by drywall studs subsequently on if you were to hang anything near the light.

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   Pull another 2-wire NM cablevision through the second switch box, just like y'all did in the very offset with the first box. The only difference is that this ii-wire cable is not a ability cablevision from the wall -- it is a free-hanging cable that you will use to attach the light. Be sure to strip nine" and pull the wires through into the 2nd switch box.

   • Be sure to secure all wires within 8" of the box.

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   Pull the ii-wire cable from the 2nd box upwardly and into the light fixture. Strip away six-9" of the sheathing and pull your wires in so that they can attach to the light. Once again, exist certain to employ a cable staple to support the wire inside 8" of the box.

9. 

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   Strip i" off of the individual ends of all the smaller wires. A 2-wire NM cable is actually made upward of smaller wires, run together for convenience. You exposed those wires already, but now you lot demand to strip the rubber sheath off of the very end of each of these little wires.

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    Curve the ends of every blackness and reddish cable into minor hooks. This volition make them easier to adhere to the actual switches. You'll hook this around a screw, which yous then tighten to clamp down the wire to the light switch.

    • The should look like petty canes.
    • This is frequently easiest with needle-nose pliers.

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    Use wire nuts to adhere the each set of two white wires together. Twist the ii white, neutral wires together in each box and twist on a wire nut. Keep twisting until the wires are secured and the nut stays in place when let go. There are two sets to attach--

    • The pair in the showtime switch box
    • The pair in the 2nd switch box

12. 

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    Utilize wire basics to attach the two pairs of green/orange grounding wires together, calculation a vi" slice of copper grounding wire to each pair equally well. Have all 3 ends and hold them together, and then twist on the wire nut and so they are all securely fastened together. You should take two wires tracing back through your NM cables, and 1 hanging ground wire on each set.

    • This actress grounding wire will be attached to the light switches. It is called a "pigtail" in electrical parlance.

13. 

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    After making all your connections, fold the wires neatly into the box. You lot want to zig-zag them, and so they come nigh a bit like an accordion. You tin tuck the wires in the calorie-free switch dorsum too -- though they didn't go any piece of work washed. Your two switch boxes should each be wired identically, like and so:

    • Two white, neutral wires tied off past a wire nut.
    • Two grounding wires, plus i pigtail, tied off past a wire nut.
    • A red wire, with the end stripped and curled.
    • A black wire, with the end stripped and curled.

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    Replace the drywall, coverings, etc. earlier moving on. By now, the wiring part is actually done. You'll just need to attach the cables appropriately to the switches and light at present -- merely the fixtures will exist uncovered past your wall anyway. Everything "backside the scenes" is mostly washed.

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1. 

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   Attach the black power cable (from the wall) to the full general screw (blackness) in the three-way light switch. Hook the curled terminate of the wire under the spiral, so tighten down the spiral to hold the wire firmly in place. This screw is usually in the upper left side of the switch and is painted black, only bank check the guide that comes with your switch if y'all're unsure.

   • Not all switches are made for three-mode wiring. Brand sure you lot purchase accordingly.
   • There should be two black wires in your box -- one from the power source, one leading to the other box. Make certain y'all use the power wire.

2. 

   two

   Attach the remaining black and red cables (from 3-wire NM) to the traveler screws on the switch. These screws, frequently gold, will be on opposite sides of the switch. Hook the cherry-red one up to the side with you blackness ability wire, and the black on the identical screw on the other side of the switch.

3. 

   three

   Adhere the hanging ground wire (the pigtail) to the dark-green grounding screw. There should only be one spiral left, and it is for that pocket-sized, half dozen" costless cablevision fastened to the grounding wires. Loop it around the screw and fasten information technology down like whatever other cable.

4. 

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   Attach the black wire leading to the light to your general screw (black). The wiring on the 2nd switch is nearly identical to the first, except for this central difference: the blackness wire goes to the lite, not to the ability source." Once you have this wire screwed down, the rest are identical:

   • Adhere the grouped cerise and black cables (from 3-wire NM) to the traveler screws
   • Adhere the pigtail wire to the grounding screw.

5. 

   5

   Attach the appropriate wires to your light fixture. You should accept a infinite for a neutral wire (white), a grounding wire, (orange or green) and a ability wire (blackness). They volition screw on easily, and your light is ready. Supersede the covers for the switches, spiral them into place, and plow the ability back on to be in business.

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1. 

   1

   Select the proper wire size. If originating from an electric console or fuse box, #12 copper is the minimum size when connecting to a 20 amp circuit breaker or fuse; #14 copper is the minimum size when connecting to a fifteen amp circuit breaker or fuse (aluminum wire on circuits of these capacities has been prohibited for many years).

   • The size of all the wires in any circuit must be the aforementioned size. When obtaining ability from a nearby electrical outlet or another circuit device, the new wiring must be the same size as those that supply the outlet.

2. 

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   Select the proper cablevision type. The power supply or feed cablevision should be "2 wire" (or usher) cable plus a ground wire. See below for descriptions and uses of common cable types.

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   Shut power off. This is a very important step. Please do non skip it.

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   Install a two wire cable between the power source (outlet box, electric panel, etc) and the showtime switch box. Leave 8–10 inches (20.3–25.4 cm) of wire inside both boxes (source and first switch) before cutting the cable to facilitate easy connection to the switch and power source. Connect the ground wire to the excursion ground wire(due south) with a wire nut or other approved connection (run across How to Connect Electric Wire). The ground wire should be continued to the neutral terminal bar. Finally, connect the black wire to the hot supply or the circuit breaker / fuse and the white to the neutral supply or neutral final bar in the electrical console.

   • If equipped with a separate footing bar, rather than connecting to the neutral terminal bar, the ground wire can connect to the ground terminal bar. Yet, if all the existing ground wires connect to one bar and all the existing white wires connect to a unlike bar, maintaining divide ground and neutral connections is required.
   • Never introduce basis wire(s) to a terminal bar with only white or grey insulated wires continued or vice versa.
   • If the power source is an electrical panel or fuse box, the cable should exist cut at to the lowest degree long plenty to reach the furthest termination point (breaker or fuse, footing and neutral bar) without the need of splicing.

5. 

   5

   Install a 3 wire cable from the first switch box to the calorie-free fixture's box. Leave 8–10 inches (20.iii–25.4 cm) of wire inside each of the boxes before cutting the cable to facilitate easy splicing and connection to the switch and fixture.

   • A 3 wire cablevision has an "extra" wire when compared to 2 wire cables, and this wire is nearly always covered in reddish insulation. This 3rd wire is necessary for 3-way switch installations.

6. 

   6

   Install a 3 wire cablevision from the second switch box to the light fixture's box. Go out 8–10 inches (20.3–25.iv cm) of wire inside each box earlier cutting the cable to facilitate like shooting fish in a barrel splicing and connection to the fixture.

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   Connect ground wires, which is usually green. ^[3] Provide as shorter lengths (8 inches/twenty.five cm) of bare or light-green insulated wire to this wire-nutted group to allow connection to green ground concluding screws on each device in the box (switches, outlets, fixtures, etc.) - one length of insulated wire per ground terminal screw. If the switch or junction box is metallic, information technology too must be deeply grounded with a greenish ground screw or approved grounding clip. This must be washed at each and every box that a cable enters and at each device that provides a termination point for ground.

   • It is highly recommended that you consummate these ground connections get-go, and then gently fold them into the rear of the box - out of the way - leaving only the shorter basis leads out for easy connection to devices.
   • No footing connection is made to plastic, cobweb or some other not-conductive box.

8. 

   8

   Connect feed wires in the kickoff switch box. Starting time, connect all ground wires equally previously described. The two wire cablevision feed from the power source enters the bottom of the switch box and the hot (black) wire connects to the common or shunt terminal on the 3-way switch. There is simply one such last on a 3-manner switch, and information technology is usually identified as the ane having a different color final screw (often significantly darker) from the other two terminal screws (non counting the light-green basis screw).

   • Connect the 3 wire cable'southward white insulated wire (neutral) directly to the ii wire 'feed' white insulated (neutral) wire with wire basics (there is no connection of any white wires to this switch).

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   9

   Connect 3 wire cable in the outset switch box. The iii wire cable enters through the pinnacle of the first switch box. The red insulated wire connects to either ane of the 2 unused last screws (shown in the image to a higher place to be on the top left and right sides of both 3-way switches). It does not matter to which concluding screw this wire is connected.

   • Connect the black insulated wire to the remaining unused concluding screw on the switch.

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    10

    Connect wires in the light fixture's box. Again, connect all ground wires as previously described, if non already completed. In the lite fixture'south box, there will be two 3 wire cables. 1 iii wire cable originates at the outset switch box and has its white insulated wire equally a neutral. The other 3 wire cable originates at the second switch box and will become the "switch leg". Mark both ends of this wire by wrapping it with blackness electrical tape to alert others working on the circuit later that it is no longer neutral. This is a newer electric code requirement, just has been a common practice whenever a white or gray wire is / or can get hot.

    • Connect the two red insulated wires together with a wire nut.
    • Connect the black wire coming from the first 3-fashion switch and the white "switch leg" wire coming from the 2nd iii-fashion switch (has black tape wrapped around it) together with a wire nut.

11. 

    11

    Connect 3 wire cablevision in the second switch box to the switch. Connect all ground wires as previously described, if not already completed. Connect the black insulated wire to the shunt or common terminal screw of the switch (one time once more, the common screw concluding is the different colored spiral from the remainder of those on the switch).^[four]

    • Connect the red insulated wire to one of the two unused terminal screws (it does not matter which).
    • Connect the "switch leg" (white wire with blackness tape) to the remaining unused terminal spiral on the switch.

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    Connect the fixture. The light fixture's box should have only a black wire, a white wire and a ground wire to supply ability to the fixture.

13. 

    13

    Finish up. Check all wire nuts for tightness and exposed neutral and hot usher surfaces. Fold all wires carefully into the boxes and secure devices and fixture with screws. Install plates and covers. Restore power and exam.

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1. 

   one

   Empathize non-metallic cables. NM (likewise called "Romex®") and UF ("underground feeder") cables both have plastic jacket wrapped around 2 (or more than) insulated wires - including one white and i black - and a single uninsulated wire.^[5]

   • NM is used indoors and UF is used outdoors, when subjected to sunlight, or when cached clandestine.
   • NM cable is easier to work than other cable types, requires no special tools or preparation, and costs less. For these reasons, it is widely used. It is non, notwithstanding, authorized for use in all installations, such as existence embedded in physical or where exposed to the risk of physical damage.

2. 

   2

   Understand armored cable types, including BX, MC and Ac. Armored cable types are very like with simply slight variations. They consist of a metal jacket formed by an interlocking, helically wound ring of steel or aluminum around ii (or more) insulated wires - including ane white, ane black, and oft 1 green. Cables lacking a greenish insulated wire apply the outer metal jacket as the ground conductor. Blazon Ac is fabricated with a continuous internal bonding conductor in contact with the metal sheath.

   • Of these armored cable types, simply Blazon NM can be installed exterior or for direct burying underground, and merely if listed (tested) and labeled for that purpose.

3. 

   3

   Know the restrictions of each cable type. There are unique precautions and instructions for each type and special connectors for armored cables. For example, exercise not use a Romex (Type NM) connector on an armored cable, even though many connectors appear like.

4. 

   4

   If the power source is from an armored cable that lacks a full size (#12 or #14) ground wire, utilise a metal box to extend the footing from the armored vanquish to the box and to the circuit's basis wire. Do this by threading a special greenish, hex-headed grounding auto screw into a pre-tapped hole in the metallic box, or use a special light-green ground clip.

5. 

   5

   Go familiar with cable naming conventions. All of these cables accept "trade names" which are basically derived from the number of insulated non-ground conductors, construction type and manufacturers' names. For instance, a "twelve-two (12/2) Romex®" cable has 2 #12 conductors, plus a full sized #12 footing. A "fourteen-3 (14/3) BX" cable is a metal-armored cable with 3 #14 conductors, plus a full sized #14 ground. Some types of BX are also tested and approved for using the sheath equally a grounding or bonding conductor.

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Add New Question

• Question

  Where can I find a expert diagram for wiring a 2 manner switch?

  

  A basic two-manner switch is pretty straight forward. You lot'll only take 3 screws. The green is for the footing wire and the other two on either side are for the black (hot) wire. The white (neutral) wire is not connected to it (it is typically but wire-nutted in the box). The idea behind a switch is that it opens or closes the connection on the blackness wire when you lot flip it.

• Question

  Can I wire a three-mode switch as a 2-fashion?

  

  Aye, but it's probably better to replace it with a regular, single-pole switch. Then you'd connect the black ability wire to one side of the switch and the black wire from the light to the other side of the switch and connect the white neutral wires together.

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Video

• Diagnose and treat problems with the switches differently depending on the relative placement of the switches and the power source.

• The "back wire-able" pick provided on some switches and outlets allows for simple insertion of a stripped wire into a hole for connection without the demand of turning a spiral. Over time, these pressure connections fatigue and eventually fail, and so the employ of screw terminals is preferable.

• When remodeling, always bank check the fuse or circuit breaker on which new lights or outlets are being installed.

• Never install a judge wire on a circuit that is protected by a breaker or fuse that has a college capacity than the wire y'all're using: 6 guess - 50A, viii gauge - 40A, x gauge - 30A, 12 gauge - 20A, xiv judge - 15A. Practise non connect smaller wires to the electric panel, unless they are the leads of a transformer for a doorbell or similar circuit.

• Use the smaller, easier to work and less expensive #14 (xiv judge) copper Romex cable if the circuit is protected by a 15 amp fuse or circuit billow. Very few three-way circuits switch loads on a 20 amp circuit.

• Information technology is not necessary to use #12 wire branching from an existing #14 wire excursion. Number 12 approximate is required by code for kitchen and dining room receptacles, and other appliances (washers, refrigerators, etc.) that require 20A service (some bathrooms are wired with #12 to back up hair dryers, etc., but is not a requirement).

• Ane wire per final. Do non connect more than than 1 wire under a screw terminal. Additionally, the wire should wrap clockwise effectually the screw. Only wrap solid wire around a concluding screw. Stranded wire will crave fork or ring terminals to exist installed (crimped or soldered) on the wire and the terminal screw tightened down on the fork or ring last.

• A 120V / 15A circuit is rated to support upwardly to 1440 watts of continuous load (estrus, lights, etc.), so you'd need quite a few lights to max-out a 15A / #14 excursion. For comparison, a 120V / 20A circuit is rated to support upwards to 1920 watts of continuous load (estrus, lights, etc.). If a larger load is to be continued, the appropriately larger sized wire and excursion breaker or fuse must be installed instead.

  • The circuit's maximum design load - in this case watts - is determined by Volts X Amps X .80, where volts and amps are given and .80 is required by the code to de-charge per unit the circuit capacity to 80% of maximum. It could exist said that the maximum amperage of a xv amp circuit is 12 amps by applying a similar formula: Circuit Billow / Fuse Ten .fourscore = maximum amp load. The aforementioned for a 20 amp circuit: xx Ten .80 = 16 amps.

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• Check you local wiring rules, as your local wiring system may use a different color combination.

• Never mix wire sizes or materials (copper and aluminum).

• Retrieve to turn off the power before yous do whatsoever electrical work.

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Things You lot'll Need

• Romex cable both 12.2 and 12.3 (for 20 amp circuits) OR 14.two and 14.3 (for 15 amp circuits).
• Two 3-way light switches
• Ane light box
• Two switch boxes.
• Wire cutters
• Wire stripper or knife.
• Wire nuts
• Straight blade and Philips screwdriver.

About This Article

Article Summary X

To wire a iii way calorie-free switch, you'll need 2 3-fashion low-cal switches, 2 two-wire not-metal cables, i 3-wire non-metallic cablevision, and 2 half-dozen-inch grounding wires. Start, run a 2-wire cable from the wall ability to the black screw on i of the switches. Then, connect the 2 switches by splitting the 3-wire cable apart and attaching each of the 3 wires to one of the other 3 screws on each switch. Finally, run the last 2-wire cable from the second switch's black screw to the light. To learn alternate wiring methods and how to ground the switches, read more than!

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