# Three-way light switch question **URL:** \ **Category:** Factual Questions\ **Created:** [November 27, 2018, 3:28am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139 "2018-11-27T03:28:38Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [November 27, 2018, 3:28am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/1 "2018-11-27T03:28:38Z")
Well, a couple, anyway. First, why are they called “Three-way?” They seem to me to only be two-way. Two switches, one light. Either one can turn on the light. Four-way I could understand, but three-way? Second (my real question), is there a way I can replace one of the switches with a timer? Like a cheap, plug-in-the-wall timer that will turn the lights on at 6 PM and off at 11PM so the burglars think somebody’s at home? I have a breeze-way between the house and a detached garage. In the breeze-way, there is a chandelier. I would like to put that light on a timer so that it would turn on at, say, 6 PM and off at, say 11PM. The switch in the garage is never used, so it would be perfect if the switch in the house would turn the light off and on, but if the inside switch was “off” the timer would still turn the light on. If the inside switch was “on”, then I would want the timer to have no effect. I’m guessing that if I replaced the inside switch with a SPST switch to the light (black wire), and replace the garage switch with an outlet (to plug my timer into) attach the outlet to an unswitched live line and neutral and take the black wire in the garage side, put a plug on it and plug it into the timer. Or, is there some better way? A light sensing switch mounted outside would be not as desirable since it wold have the light on all night, which is what I am trying to avoid. ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [November 27, 2018, 3:47am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/2 "2018-11-27T03:47:30Z")
First question, it’s mostly an American-ism. It’s because there are three oversimplified states: both “up”, both “down”, and “opposite”. Technically, ‘up-down’ and ‘down-up’ are distinct, but those don’t get counted separately around here. Second question, sure, just head to your local home improvement store and ask for a timer switch. I don’t know what your budget is exactly, but there are switches that do exactly what you want. You could replace your inside switch with one of these and it’ll have a timer function with manual override. ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [November 27, 2018, 3:49am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/3 "2018-11-27T03:49:43Z")
Came back in to add, [here](https://www.homedepot.com/p/Defiant-15-Amp-In-Wall-3-Way-Daylight-Adjusting-Digital-Timer-Switch-with-Screw-Terminals-White-32648/300524126)’s one such switch for $20. Not sure how it’s programmed, but there’s bound to be instructions. ---
**Author:** ![K2500](https://avatars.discourse-cdn.com/v4/letter/k/f6c823/32.png) [@K2500](https://boards.straightdope.com/u/K2500)\ **Post date:** [November 27, 2018, 3:51am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/4 "2018-11-27T03:51:30Z")
Something like this? [https://www.leviton.com/en/products/vpt24-16z](https://www.leviton.com/en/products/vpt24-16z) ---
**Author:** ![K2500](https://avatars.discourse-cdn.com/v4/letter/k/f6c823/32.png) [@K2500](https://boards.straightdope.com/u/K2500)\ **Post date:** [November 27, 2018, 3:58am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/5 "2018-11-27T03:58:13Z")
> [@K2500](#): > > Something like this? [VPT24-16Z - Indoor Decora 24-Hour Programmable Timer - Leviton | Products](https://www.leviton.com/en/products/vpt24-16z) I missed the edit window: That one I posted is like 80$ apparently, and requires a neutral, which I assume you have becuase you mentioned installing a recptical in its spot. The one in post above looks decent but I’ve never used them. Parallel single pole switches, one with timer function would give you the override “on” option you want. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [November 27, 2018, 6:57am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/6 "2018-11-27T06:57:26Z")
If you have the budget. Get a timer with double pole single throw contacts. You will need to add a extension box to one of the switch boxes. Determine which are the runner wires and which is either the power lead or the line going to the light. On one side of the timer contacts connect the contacts together and connect to the 3 way switch that is either the power lead or the line going to the light. Connect one runner line to the switch in the normal place and to one timer contact. Connect the other runner line to the other side of the switch and the other timer contact. If the time clock is off the 3 way switches will work normally. But when the time clock contacts close the light will come on no matter the position of the 3 way switches. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [November 27, 2018, 9:29am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/7 "2018-11-27T09:29:40Z")
> [@Great\_Antibob](#): > > First question, it’s mostly an American-ism. It’s because there are three oversimplified states: both “up”, both “down”, and “opposite”. Technically, ‘up-down’ and ‘down-up’ are distinct, but those don’t get counted separately around here. They are ‘three-way’ here too and for exactly the same reason. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [November 27, 2018, 10:17am UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/8 "2018-11-27T10:17:41Z")
> [@Great\_Antibob](#): > > First question, it’s mostly an American-ism. It’s because there are three oversimplified states: both “up”, both “down”, and “opposite”. Technically, ‘up-down’ and ‘down-up’ are distinct, but those don’t get counted separately around here. The switches themselves are called “three-way” as slang in Spanish (_de tres vías_), not because of positions for their combinations, but because the switches have three cable connections: each cable is a pathway for the current. A normal switch only has two. ---
**Author:** ![Gedd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gedd/32/4938_2.png) [@Gedd](https://boards.straightdope.com/u/Gedd)\ **Post date:** [November 27, 2018, 1:00pm UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/9 "2018-11-27T13:00:59Z")
> [@Nava](#): > > The switches themselves are called “three-way” as slang in Spanish (_de tres vías_), not because of positions for their combinations, but because the switches have three cable connections: each cable is a pathway for the current. A normal switch only has two. Oh dang, I knew that. I think this gets my vote. Wait, maybe it’s just that both are reasons for the name. ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [November 27, 2018, 2:17pm UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/10 "2018-11-27T14:17:28Z")
Thanks to all. I better understand things, now. **Nava** , the explanation of three wires vs. two wires makes the most sense to me. Both types of switches only have two positions (up or down), so the “number of positions” explanation sounds more like it came after the fact. I had looked online for one and all I could find was one like **K2500** posted, but was way too pricey, which is why I was looking for an alternative. The switch that the **Great Antibob** posted (I see why he’s called “Great”) looks like it will fit the bill and priced to meet my budget. > [@Great\_Antibob](#): > > Came back in to add, [here](https://www.homedepot.com/p/Defiant-15-Amp-In-Wall-3-Way-Daylight-Adjusting-Digital-Timer-Switch-with-Screw-Terminals-White-32648/300524126)’s one such switch for $20. Not sure how it’s programmed, but there’s bound to be instructions. ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [November 27, 2018, 4:02pm UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/11 "2018-11-27T16:02:49Z")
> [@Nava](#): > > The switches themselves are called “three-way” as slang in Spanish (_de tres vías_), not because of positions for their combinations, but because the switches have three cable connections: each cable is a pathway for the current. A normal switch only has two. I vote for this explanation too. Especially since a “four-way” switch (which is added between two three-way switches) has four wire connections. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [November 27, 2018, 5:50pm UTC](https://boards.straightdope.com/t/three-way-light-switch-question/825139/12 "2018-11-27T17:50:22Z")
> [@excavating\_for\_a\_mind](#): > > Thanks to all. I better understand things, now. **Nava** , the explanation of three wires vs. two wires makes the most sense to me. Of course, they probably really have 3 wires and 4 wires because we’re not counting the ground. I was confused for a bit by the fact that Romex-2 has 3 wires and Romex-3 has 4 wires in it.