Use your Camera to Switch a Light On: Part 1

January 8th, 2021

Wireless CCTV cameras let you see your home or business from anywhere, using the internet, which is amazing enough. Imagine, though, that you log in to take a look at your property and you can’t see the view because the room is too dark. If you were there, you would switch a light on. Incredibly, you can now use your wireless CCTV camera to do just that, even from the other side of the world. In part one of this two-part series, we look at what equipment your local provider in offer which you will need to achieve this.

Most good quality wireless CCTV cameras have an I/O or input/output port. To use the cameras to control a light, we will be using the output port. You will probably need to check the camera manual to find out what current and voltage the camera is capable of sending out from the output port, as you will need this information when choosing the equipment to make everything work properly.

A short safety note before we begin. You will be cutting and joining mains wiring here, so if you have any doubts about this or if local regulations state that a qualified person must do this, then you cannot go ahead.

You will need a few pieces of inexpensive equipment to achieve your goal of switching a light on or off in your home by using the internet, the main component being a relay switch which your provider in offers. This device is a switch in a mains voltage circuit that can be controlled by applying a very low current to a second low voltage circuit. It has four connectors, two low voltage, and two mains voltage. One wire of a mains power cable, typically the live wire, is cut and the ends connected to the mains voltage outputs of the relay, thereby breaking the mains power supply. The low voltage connectors are the inputs and accept a small current. Only when a current is detected at the inputs does the relay complete the circuit between the two mains voltage output connectors and thereby restore power to the mains circuit. When choosing a relay, make sure that the output voltage and current rating matches your mains circuit, and also that the input rating of the relay matches the rating of the output port of the camera.

Apart from the relay, you will need a few other bits and pieces and a mains voltage lamp. A simple table lamp is easy because the wiring is accessible. You will need a length of alarm cable to run between the camera and the relay switch. (We only need two strands but you will probably only be able to get four- or six-strand cable.) As the relay switch will need to be wherever the lamp’s mains cable is, get enough alarm cable to allow for this. The relay switch itself will either come within a plastic box that can be screwed to the wall or will be small enough to fit quite neatly into a so-called pattress: a box such as the one used in surface-mounted standard mains switches or sockets. If you are using a pattress, you will also need a blanking plate for the front of it as we will not be using it as a manual switch or mains socket.

At this point, you will have everything you need to get started. In part two of this series, find out how to put everything together so that you really can switch a light on in your home from the other side of the world.