i don't know much about light switches, but this is the first time i've encountered a 3 wired switch. All i know is 1 of them is a common. The problem is i don't know how to convert or wire the 3 wired switch to a new switch nowadays. See pics below

Old Switch

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New Switch

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I really don't have an idea how to wire them. The switch has 2 bulbs connected to it.


In your old switch I expect the middle wire is the permanent live (hot) and the left and right wires each go to one of the two lamps. You can see that the left wire is not actually connected to the upper switch.

This is a system of wiring lights known as a "switch loop". In this system there are no neutral wires running to the switch.

You don't show any ground (earth) wires either, which would be very strange where I live but may be have been normal in the past where you live.

You can check which wire goes to which lamp by turning off the circuit breaker, checking the circuit is dead and then undoing the right wire. Make it safe by applying electricians tape or by inserting it into a loose wire-nut or terminal block. Then you can turn on the circuit breaker and see which one of the two lights no longer turns on.

The new switch should have come with connection instructions. If not, I would use a continuity tester to find the common connections and the switched connections in the new switches before installing them.

On closer inspection, I see there is a connection diagram moulded into the back of each switch

moulded diagram

I would wire it like this:

new switch

Note that you need to cut the middle wire shorter and you need a new insulated piece of wire to connect the "common" terminals of the two switches

The new switches also have an insulation-trimming guide moulded on the back, which you should use if possible.

If the new switch is a smart-switch of some sort it probably needs a neutral connection. In that case you need to call an electrician to run new wires from a junction box to the switch. The electrician may need to make holes in your walls ceiling or floors which will need repairing and redecorating.

  • yep, i exactly did this one. connected the "common" on the upper right side and i added a strip of wire to connect middle right and bottom right wires. i did this after some research. Still don't know the exact terms but i got your point
    – lemoncodes
    Nov 18 '18 at 10:42

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