How Smart Switches Usually Work?
Nov. 11, 2021
Smart light switches are a useful invention and some people prefer them to smart light bulbs because they allow you to turn the lights in a room on and off in a fairly natural way. Smart switches are connected to the appliances in your home and replace the existing light switches in the room. As a result, they end up only controlling the light bulbs that the switch previously controlled (unlike smart bulbs, which can be managed independently as long as there is power flowing to them).
Smart switches are therefore ideally suited to many "utility" or "task" based rooms, such as kitchens, utility rooms and bathrooms, where you may only want to turn the lights on or off. Smart switches are perfect for this, especially as some models have built-in motion sensors that automatically switch on the lights when you walk into these rooms.
Smart Switch
Once they are connected to your house, the smart switches draw power (more on this later) and then use a communication protocol to 'talk' to a central hub, allowing you to turn the switches (and lights) on and off using a smartphone app or smart speaker. This 'communication protocol' is usually WiFi, which means that the smart switch can be connected to your home network just like TVs, phones and other devices. The Smart Switch can then communicate (securely) with the Internet.
Alternatively, smart switches can sometimes use different communication protocols, such as ZigBee and Z-wave, which use less power and are more reliable than WiFi. Either way, the main thing to know is that the smart switch must consume some power (with or without a neutral wire) in order to be intelligently managed via your app or smart speaker. The following two sections cover this in more detail.
Smart switches with a neutral wire
Most smart switches on the market require a neutral cable, this is because any US house built from the 1980s onwards should have a neutral (white) cable connected to the light switch base box. In this way the ZigBee smart switch is connected between the neutral cable and the mains hot wire and will therefore draw power in the usual way.
Smart Switch
In this configuration, the ZigBee smart switch will control the power to the lights via the load hot (red) wire. Only when the switch is open (physically or via the smart function) will the circuit be complete and power will flow to the lamp. Otherwise the circuit is broken and the light does not come on.
Smart switch without a zero wire
As long as no zero wire exists, a simple 2-wire circuit can be used to power the lamp. The hot and earth wires go into the switch and the hot wire (called the power hot wire) is a permanent live feed from the mains of the house.
The switch then connects another hot wire (known as the load hot wire or switch leg wire) to the light fixture. The switch completes the circuit: when it opens, the circuit is complete and the load hot provides charged power to the bulb - turning it on.
When the switch is closed, the circuit is broken and no current flows. This works fine overall, but it can cause problems for the smart switch, which must provide its own (small) power supply for the smart function to work properly.
If you want to get more information about the best ZigBee smart switch, welcome to contact us today or request a quote.
