Cooker Switch Installation Guide
A cooker switch is a useful means of isolating electric cookers, hobs and grills for installation, maintenance or emergency without having to isolate an entire circuit at the consumer unit. They’re designed to carry the heavy load that cookers demand, while being able to be safely switched on and off when the circuit is in an on-load or an off-load state.
As many cooker switches are built into wall sockets that also contain a regular plug socket, it’s vital that such switches comply with BS4177, so make sure you read up on the standard before continuing. You should hopefully already be familiar with BS7671, which covers wiring more broadly.
Safety first
If you’re installing a cooker switch in the kitchen, or even replacing an existing one, you should always use the services of a qualified electrical contractor. Kitchens and bathrooms are special cases when it comes to electrical repairs, replacements and installations because of the presence of water, so if you’re not a qualified electrician, stop now and call one up.
Choosing a cooker switch
The vast majority of cooker switches are 45 amp fused spur models, although you can find higher ratings (e.g. 50 amp) if you’re running a cooker that’s likely to have all of its components (grill, stove and hobs) running simultaneously, or if you have a particularly large cooking setup. Cooker switches that have a regular plug socket built in will specify the two different ratings (e.g. 45A and 13A).
Aesthetics and available space will also play a part in your choice. Like all switches, cooker switches come in various sizes and finishes, such as brushed metal, brass switches, chrome or plastic.
Preparation
The cooker switch installation has four main components:
- The consumer unit
- The switch
- The connection unit (cooker outlet)
- The cooker
Each component is wired to the next, starting with the consumer unit and terminating at the cooker. 6mm twin and earth is wiring recommended for all lengths, unless the wiring is surface mounted, in which case 10mm wiring should be used. The switch is usually joined to the connection unit with wiring embedded in the walls for a neater appearance. The cooker outlet is basically a set of terminals that allow you to connect a new cooker permanently via flexible cable, and it too is mounted in the wall behind the cooker. The cooker cannot simply be unplugged like regular appliances – it’s permanently wired up, hence the need for a separate switch.
If the job is a straight swap of an old cooker switch for a new one, and everything else is staying the same, this guide will cover those basics. However, if there’s a major change, such as the cooker being moved or a complete new installation, it’s a much more involved task, which will require all the drilling, chiselling and plastering associated with such an installation.
Replacing an old switch
If you’re removing an old switch and replacing it, start by isolating the circuit at the consumer unit, or shut down the property’s electrics altogether. Carefully remove the switch’s screws and pull the faceplate clear, then confirm that the current is dead by using an electrical tester.
Once satisfied, you can proceed to fully remove the faceplate and undo the live, neutral and earth wires. As the switch allows current to pass through it, there should be two sets of each type, all emerging from the wall. Make sure you note which ones are leading to the consumer unit and which are continuing to the connection unit.
Now, you can reverse the steps above using the new switch, taking care to note that you are connecting the correct cables to the switch’s terminals.
Installing a new switch
If the switch is in a completely new location, that probably also means that the cooker and connection unit will also be in new locations. Alternatively, it could be a completely new kitchen or one where no cooker was originally present.
When installing a new switch and cooker outlet, you (and/or the homeowner) must decide whether the wires will be sunk into the walls, behind skirting boards or surface mounted. Similarly, will you be sinking the back boxes into the wall, or will they stand proud on pattress boxes?
These decisions might be aesthetically or space driven, but there are also budgetary considerations – using surface wiring and pattress back boxes makes for a quicker (and cheaper) job. If you’re chasing out the plaster and masonry and sinking the back boxes, that will have to be considered with regard to man-hours and material cost.
Installing the switch and connection unit is relatively straightforward if you’ve ever fitted a regular socket or light switch. You’ll need to run the wire from the consumer unit to the switch, connecting your 6mm or 10mm T&E cable to the switch following the normal brown (live), blue (neutral) and green/yellow (earth) wires to the relevant terminals. The earth cable will be bare, but some electricians like to put a yellow/green sleeve around the exposed copper to make it clearer for any future electricians.
Making sure you’ve connected the correct colours, you then run more cable from the switch to the connection box. You can now loosely replace the faceplate on the switch.
Test and finish
Now, you can test the wiring and the switch by turning the current back on at the consumer unit and touching the wires with your electrical tester. If everything is good, you can secure all the faceplates in place and, if necessary, tidy up the job with capping and plaster, ready to be decorated.
The final stage of the wiring can only be completed when the cooker is present, as you’ll be using the cooker’s own wires to connect it to the cooker outlet on the wall. If the cooker is not yet present, replace the faceplate of the connection box to make it safe should the switch accidentally be turned on. Otherwise, you can connect the cooker as per the manufacturer’s instructions and test it.