two way switch question switch wont work unless the other is in a certain position?

[Andy Jarchow]

Hello all,

While inspecting a home yesterday I was trying to figure out what function each wall switch has. Two switches I found operated the garage lights. One switch was in the garage and the other in the house. One of the switches would not work unless the other was in a certain position.

Does this mean it is the wrong type of switch ie. 2way, 3way…? Or is this normal?

Thank you

mk

[James Duffin]

It means that one of the two switches is wired incorrectly.

[Garry Sorrells]

Yes, wired wrong, one option. Most likely & typical cause. The older switches do not look like the newer ones, ie. 1945 /1990. So people have a problem replacing them correctly.

Bad switch is also possible.

The actual wire usual not the problem.

[Bruce King]

Be careful reporting the repair process since this could very well involve an incorrect cable that would require running a new cable or wire. Two switches for one device needs two 3-way switches with two traveler wires between switches. Some older homes were wired wrong or someone tried to install 3-ways and failed to run the correct wire.

[Vern Heiler]

I most often find this where a dimmer has been installed. Always check operation in all combinations of switch settings.

[H.G. Watson, Sr.]

Hello all,

While inspecting a home yesterday I was trying to figure out what function each wall switch has. Two switches I found operated the garage lights. One switch was in the garage and the other in the house. One of the switches would not work unless the other was in a certain position.

Does this mean it is the wrong type of switch ie. 2way, 3way…? Or is this normal?

Thank you

mk

Multiple location switching involves three-way switches, one at each end of the control path, if more locations within the run of the travelers, four way switches are installed in between the beginning and ending 3-way swtiches. (No "2-way" switches). 3-way and 4-way switches are not indicating (do not say "on/off").

Generally, the symptoms you describe are usually attributed to either a wiring error, or having installed an incorrect switch (3-way and 4-way switches look similar - difference is an additional screw post).

However, it may be that this is not a 3-way switch loop at all, it may be that there are two single throw switches in series - this is allowed, but can be confusing.

If the garage is not attached, and is not otherwise electrified, except via the garage switch: it may be that the switch local to the garage is acting as the disconnect for the structure.

[Jerry Peck]

Several possibilities, including but not limited to:
- bad switch
- broken conductor (broken for various reasons, even a nail)
- wired wrong
- one switch is a single pole switch and not a 3-way switch
- etc.

[Andy Jarchow]

Very helpful!:D

Thank you all
Have a great week
mk

[Bob Elliott]

Must be in series.