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hooking up 3 way switches

5K views 16 replies 9 participants last post by  norcalsurfer1977 
#1 ·
hello,

i'm replacing 2 3 way switches that both control two hallway lights. the old switches are very outdated, but i'm having a problem with the new ones.

i can get them both hooked up to turn on/off the lights, but when one switch is off, the other won't work. i don't know what's going on.

in the first box the black wire is the hot, which i attach to the common. then the red and white are travelers and w/out power.

in the second box, the black has no power, and the red and white are powered.

i've tried every combination on the 2nd box and can't get it to work correctly. the old switches weren't grounded to the box. could it be something w/the new switches?

thanks!
 
#3 ·
Follow these steps if you can.

Separate all 3 wires from each switch, find the only hot wire. Between the 2 switches only one will be hot if wired correctly.Put that hot wire on the common. If using Decora style switch, look very closely for the common, it fools many!

In the same switch box put the remaining 2 wires on the remaining screws on the 3 way.

At the other switch location - wires sticking out of box -only one wire will now be hot,that will be a traveller. At the previous switch turn the switch to the opposite postion. A different wire will be hot back at the other switch location, this is the second traveller. The remaining wire in the switch box will be your common.

If using an inductive type tester that may be giving you a false reading, test hot to ground if possible. Good Luck!
 
#4 ·
thanks uncleduey, i believe i can follow your steps.

although, when both switches are off of the box altogether, and the wires are sticking out of the box and the power is on, box 1 has 1 hot wire. box 2 has 2 hot wires. i thought box 2 would be dead until getting power from box 1?
 
#7 · (Edited)
in the first box the black wire is the hot, which i attach to the common. then the red and white are travelers and w/out power.

in the second box, the black has no power, and the red and white are powered.
Simple.

In the second box, the black is common.



The power comes from the first switch to the second on either the red or white wire depending on the position of the switch.

The second switch sends that power to the fixtures in the same manner.
 
#10 ·
3 way switch

you are using the wrong type of tester those voltage "detectors" are only made to sense the magnetic field from AC current, they will usually beep if any wires in the box are hot and sometimes from a voltage imbalance on the neutral wire. Which means the wires you think are hot are not. You need to use a "contact" type tester and touch one lead to a wire and the other lead to ground (or neutral)

Be careful, you could have done the same thing with the power off using a continuity tester to find whih wires are travellers, leaving the commons as the last to hook up.

Remember a dead circuit NEVER killed anyone :eek:
 
#12 ·
Please describe the wiring in each switch box. Something in my opinion is missing.

For example is there only one cable coming into each switch box with a red,white and black wire plus ground or is there more than one cable in a switch box beside the 3 wire with ground cable ?
 
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