Helpful video reference. The video above covers wiring a cooker control unit to an electric oven in the UK, including identifying the supply and load terminals and making the connections correctly. It is worth watching end-to-end before you open the unit.
1. Understand what you are working on
A standard UK cooker control unit contains a 45 A double-pole switch (switching both live and neutral) and often a switched 13 A socket for a kettle or toaster. It has two cable entry points: SUPPLY (from the consumer unit) and LOAD (to the cooker).
If you are replacing a like-for-like unit on an existing circuit that is already sized correctly, this is typically not notifiable work. If the circuit, its cable, or the consumer unit connection needs changing, that is notifiable under Part P and a registered electrician should do it.
2. Isolate and prove dead
At the consumer unit, switch off the cooker circuit MCB. Tape it off or pocket the fuse if you have a rewireable board. Go to the control unit and test with a voltage tester between live and neutral, live and earth, and neutral and earth on the supply terminals. All must read dead before you do anything else.
3. Remove the old unit and photograph
Unscrew the faceplate. Most cooker control units have a separate terminal block or backplate that stays screwed to the wall. Ease the unit forward and take a clear photograph of every conductor and every terminal before you disconnect anything. You will thank yourself later.
4. Connect the supply side
The supply cable comes from the consumer unit. Strip the conductors to the length the terminal manufacturer specifies (usually 8-10 mm). Insert into the SUPPLY terminals: brown to L, blue to N, green/yellow to earth. Tighten each terminal screw firmly but not so hard that you cut through the strands. Give each conductor a firm tug to confirm it is held.
If the cable entering the control unit has the old colour code (red, black, with a bare earth), sleeve the bare earth in green/yellow sleeving before connecting. Note that red = live and black = neutral in old colours.
5. Connect the load side
The load cable runs from the control unit to the cooker connection box or directly to the cooker terminals. Connect it to the LOAD terminals using the same colour code: brown to L, blue to N, green/yellow to earth. Do not mix up supply and load - current must flow in through SUPPLY and out through LOAD.
6. Check the earth path on the back box
If the back box is metal, it must have a flying earth lead connecting it to the earth terminal on the control unit. This is what protects against the box becoming live if a conductor worked loose. Plastic back boxes do not require this, but the earth conductors in the cables still need to be connected.
7. Refit and test
Fold any excess cable carefully into the back box. Offer up the control unit faceplate and check nothing is pinched before tightening the screws. Restore power at the consumer unit. The switch should operate without tripping the MCB or RCD. Connect the cooker and test that it heats up correctly.
When to call us
Swapping a like-for-like cooker switch is a manageable job. But if the circuit cable needs extending, the back box needs moving, or the consumer unit connection is involved, it becomes notifiable work. Richard handles cooker circuits and control unit replacements in Sandwich and across east Kent.
Need a cooker switch fitted in Sandwich?
Richard can replace a cooker control unit or run a new cooker circuit. Sandwich town is a short drive from the workshop.
Contact Richard