What Are The Different Type of Light Switches?
On the surface a switch can just look like any other switch, but in reality there are plenty of different types of switches that can be used in different applications. Let’s take a look at some of the more common types of light switches
Single Pole Single Throw (SPST)
A single pole switch is one of the most common types of switches and they are as basic as switches can get. With a single pole switch the circuit is either open or it is closed.
Single pole switches are often required in basic lighting circuits.
The diagram below shows how a single pole switch works. In this example this shows a closed switch:
Single Pole Double Throw (SPDT)
From the outside, a Single Pole Double Throw switch typically looks the same as a Single Pole switch, however there are two outputs (or throws) that can be switched between
We can distinguish this as a SPDT switch because there is a single common input on one side of the switch (top) and two outputs on the other side of the switch (bottom).
Single Pole Double Throw switches are often used in lighting circuits for two reasons:
- A SPDT can perform the role of a SPST switch - one of the outputs just remains unused
- SPDT switches are often used in hallways or other settings where two way switching can be required.
Momentary Switch
A momentary switch is a switch that is usually open, but is closed whilst pressed. When the switch is released the circuit will open again. As a result of this behaviour, momentary switches aren't overly common in lighting setups. However, most Shelly devices can use a momentary switch as a toggle switch where pressing the switch will turn the light on or off depending on the current state of the light.
Rotary Switch
Rotary dimmers are often used in situations where the brightness of the light needs to be controlled. A rotary dimmer will only work with dimmable light bulbs.
A rotary switch is not compatible with a Shelly Dimmer 2, however you can use Retractive switches to allow you to turn lights on and off as well as controlling the brightness level.
Retractive Switch
A retractive switch can be thought of as a variation on a momentary switch where the switch can be pressed, but once pressed the switch will return to its original position.
A retractive switch can often be useful for using with a Shelly Dimmer 2 where a basic press can act as an on/off toggle and a press-and-hold of the switch can adjust the brightness.
In this specific instance our retractive switch is part of a grid switch system that allows us to customise what switches are used in the face plate:
