# I want to control a light with two switches, but not a three way

Not a traditional three way switch, but I want if either switch is on, the light comes on. Both switches have to be off for the light to go off. If both switches are on, the light should be on - but not over powered.

• I doubt it would be in code since you would have to split the hot into two wires, go though each switch and back to the light. I am sure the electricians/code masters will show how wrong this is. Maybe with a light with two separate hot posts. Commented Aug 8 at 17:09
• 1. Do you already have a standard 3-way circuit and want to modify it to what you describe? Or 2 are you planning to wire this light from scratch? Commented Aug 8 at 18:11
• Joe wants his two switches in a Boolian OR (i.e., inclusive OR) in which light is ON if either S1 or S2 is ON or both are ON. This way the light can be kept ON by setting one switch ON and protecting it. The usual set-up with two 3-way switches is a Boolian XOR in which light is ON if either S1 or S2 is ON but NOT when both are ON. In the XOR arrangement locking either of the switches ON does NOT prevent the light from being switched OFF by the other switch. Would you care to say why you want to do this? (I was taught to do things weird when I lived in Austin and still do at 80 yo.) Commented Aug 8 at 21:38
• Joe, you do not have to worry about two hot conductors in parallel "over powering" the light. The total current and power will be determined by the resistance of the light. The two hot conductors are at the same voltage, the current will be divided between the two paths if both switches are ON. If one switch is OFF, then all the current will go through one conductor. Commented Aug 9 at 0:55
• @Huesmann the OP wants a setup where there are three states where the light is ON and one state where it is OFF. The normal arrangement has two states where the light is ON and two states where it is OFF. Commented Aug 9 at 20:29

The key issue is that all current flowing in both directions (e.g., hot and neutral, but can also be hot and switched hot, etc.) must be in the same cable or conduit. With a traditional 3-way, you have two travelers, with at most one hot at any time. However, for this setup you can do the following:

• Power from panel 2-wire cable to first switch, 3-wire cable between the two switches, 2-wire cable to light - the same basic setup (but different connections) as an ordinary 3-way switch

First switch box:

• Black (hot)/white (neutral) to first box
• Black connects to both switch 1 and the black wire in the 3-wire cable
• White connects to the white wire in the 3-wire cable
• Second connection on switch 1 connects to red wire in the 3-wire cable

Second switch box:

• Black (switched hot)/white (neutral) to light fixture
• Black connects to both switch 2 and the red wire in the 3-wire cable
• White connects to the white wire in the 3-wire cable
• Second connection on switch 2 connects to the black wire in the 3-wire cable

With this configuration:

• White is always and only neutral (that is generally the case with new 3-way switch installations because of the relatively new requirement for neutral in switch boxes, but not always the case in the past)
• Black in the 3-wire cable is hot but only powers the light if switch 2 is on
• Red in the 3-wire cable is switched hot and only powers the light if switch 1 is on
• If both switches are off, the light is off
• If switch 1 is on, red becomes hot and powers the light, with red and white equal/opposite current
• If switch 2 is on, black carries current through to the light, with black and white equal/opposite current
• If both switches are on, black and red nominally carry 50% of the hot current each and white equal/opposite current. But if there is any imbalance between black and red they still balance white in total. Because all 3 wires are in one cable, this is code compliant no matter how much current is on red vs. black, similar to a double-switch fan/light.
• Perhaps in your answer you should make it clear that you are envisioning the two switches are single pole switches. The OP has not stated whether he already has a normal arrangement with two 3-way switches. If he does, you could advise them that he could keep them and use them as simple switches so he would not have to buy new switches. That way the 3-way switches would be there if later someone wanted the normal arrangement. Commented Aug 8 at 20:03
• Also the OP did not state where the line hot enters the circuit. If the line hot (and its neutral) enters in the box for the light, then the specific details of the wiring would be different. OP has not stated whether he is wiring from scratch or is modifying a standard setup of two 3-way switches. Commented Aug 8 at 20:08
• @JimStewart Good points. I am working under the assumption that OP is starting from scratch, not revamping an existing 3-way, and using single-pole switches since 3-way switches are not needed. Commented Aug 8 at 23:28

Lets change the scenario to something that is a common design problem. Sometimes we have a Men's and Women's Bathroom with a common exhaust fan. Your logic be the same as your question.

• Sw1 on + Sw2 on = On
• Sw1 off + Sw2 on = On
• Sw1 on + Sw2 off = On
• Sw1 off + Sw2 off = Off

If you use 2 SPST Sw's you can run the line side of the circuit to matching posts on Sw1 and Sw2. Then run the switch leg from each switch to the exhaust fan and connect them together pigtailing it to the exhaust fan. The important part is that the fan and switches must be fed with only one circuit. In effect you are paralleling two start switches.

Hopes this helps.

• I suppose that could work. Only catch is that modern code requires /3 in the switch loops to have neutral available. So you haven't actually avoided /3 cable. (Well, unless conduit but that's less common.) Commented Aug 9 at 20:38

I think everything's already been covered above, but it's very simple and you just need two 3-way plug-in wire clamps to split and combine the wiring to and from the switches:

I'm unfamiliar with the wiring color code used in the US, but for EU it would be:

• Phase up to switch: brown
• Switches to light: black
• Return/neutral: blue