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Two Way Switching Using a Shelly

Two Way Switching Using a Shelly

In this guide we will explain how a Shelly 1L can be used to provide two way switching

What is Two Way Switching

Two way switching allows you to control a light from two different light switches.

Two way switching is often common in the following scenarios:

  • In a hallway or landing, where a switch at the top of the stairs and a switch at the bottom of the stairs will control the same light
  • In a room with multiple entrances where you may have a switch by each entrance that controls the same light

Can I Use a Shelly to Perform Two Way Switching?

Yes, you can use a Shelly 1L for two way switching,.

How Does Conventional Two Way Switching Work?

A conventional two way switching setup will look like this:

Diagram showing traditional two-way switching

With two way switching you have a pair of SPDT  (Single Pole Double Throw) switches.

Each switch has a single common (pole) and two throws.  The common of one switch is connected to the live feed, and the common of the other switch provides the switched-live feed to the light.

The throws of each switch are then connected to each other. So in the diagram above, the left throw on the 1st switch is connected to the right throw on the 2nd switch and the right throw on the 1st switch is connected to the left throw on the 2nd switch.

This specific way in which the throws are crossed over results in a circuit where switching either switch will toggle between closing and opening the circuit, regardless of which switch was the last to be used.

How Do You Wire a Shelly 1L for Two Way Switching?

There are a few similarities between traditional two-way switching and two-way switching when using a Shelly. We still need a pair of SPDT switches, however the link between the switches occurs via the Shelly SW1 and SW2 terminals rather than by using a pair of switched live wires between the two switches.

Diagram showing two-way switching using a Shelly 1L

The settings for the Shelly will need to be changed via the Shelly app so that SW1 and SW2 behave as toggle inputs.


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