Here's the short answer: brown goes bottom-right, blue goes bottom-left, green-and-yellow goes to the top. Remember it as BR and BL — BRown is Bottom Right, BLue is Bottom Left. Five minutes, one screwdriver, and a plug wired better than half the ones we see brought into the shop.
The longer answer is worth your time, though — because a plug isn't just three wires and a prayer. There's a fuse decision most people get wrong, a clamp most people use incorrectly, and one small trick professional electricians build into every plug they wire that could genuinely save a life.
We've been on the trade counter in Birmingham since 1975. Wiring a plug is the first job most sparks ever learned — and it's still the one where we see the most confident mistakes.
1. The Wiring Colours, Decoded
Every UK appliance flex made since 2006 uses the harmonised colours:
- Brown = Live. Bottom-right terminal — the one connected to the fuse.
- Blue = Neutral. Bottom-left terminal.
- Green/yellow = Earth. The top terminal, on the biggest pin.
Working on something older? Pre-2006 flex used red for live, black for neutral, and plain green for earth. Same positions, older wardrobe. If your flex has red and black cores, it's at least twenty years old — have a good look at its condition before deciding it deserves a new plug at all. More on that in section 5.
First, though, the decision everyone skips: the fuse.
2. Which Fuse? Use the 700-Watt Rule
The fuse is not decoration. It's sized to the appliance, and the rule of thumb is simple:
- Up to about 700W → 3A fuse. Lamps, phone chargers, TVs, radios, laptops.
- Over 700W → 13A fuse. Kettles, toasters, heaters, irons, washing machines.
Check the rating plate on the appliance — the wattage is printed on it. Fit the smallest fuse that covers the load, because the fuse's whole job is to fail before the flex does.
Trade tip: the "13A fits everything" habit is the one we hear most across the counter. A 13A fuse on a 60W lamp will happily let the thin flex cook long before it blows. Size the fuse to the appliance, not the plug.
If you're spreading one socket across several devices, do it through something fused and certified — the Knightsbridge 13A 3-way fused adaptor carries its own replaceable 13A fuse and BS 1363 certification, so the protection travels with it.
3. Wiring the Plug: The 5-Minute Method
- Unscrew the plug cover and loosen the cord grip — the plastic clamp at the cable entry.
- Strip back about 40mm of the outer sheath, taking care not to nick the coloured cores.
- Cut the cores to length so each one reaches its terminal with a little slack — and leave the earth core the longest. More on why in a second.
- Strip about 5mm of insulation from each core and twist the strands tight, so there are no stray whiskers.
- Insert each core fully into its terminal — brown bottom-right, blue bottom-left, green/yellow top — and tighten the screws firmly.
- Tug test. Pull each core. If anything moves, re-do it.
- Clamp the cord grip over the outer sheath — never over the coloured cores — and screw the cover back on.
Trade tip — the trick the professionals use: cutting the earth core longest means that if the cable is ever wrenched out of the plug, live and neutral pull free first and the earth is the last to let go. It's a built-in fail-safe that costs you nothing but ten seconds of thought.
4. The Mistakes We See Every Week
- The cord grip clamping the cores instead of the sheath. The grip takes the strain of every yank the cable will ever get. Clamped on the thin cores, one good pull exposes live copper.
- Copper whiskers. One loose strand bridging two terminals is a short circuit waiting for you to plug in.
- Foil, screws or nails where the fuse goes. Yes, still. In 2026. Please don't.
- Wiring a beautiful new plug onto a damaged flex. If the cable is nicked, perished or has been trapped in a door, the plug isn't the problem.
And if the reason you're rewiring is one socket doing too many jobs: a properly rated, surge-protected extension lead is the safer answer than a tower of adaptors.
5. When Not to Bother
Moulded plugs on modern appliances are sealed for a reason — don't cut one off unless it's damaged, because a cut-off moulded plug left in a drawer is a shock hazard with legs. If a plug is cracked, scorched or warm to the touch in use, replace it rather than repair it. And if the flex itself is damaged, replace the flex — a task worth handing to someone qualified on anything more serious than a table lamp.
Everything else here is legitimate, legal DIY. Wiring a plug isn't notifiable electrical work — it's basic maintenance, and every household should have one person who can do it properly.
Your Plug Wiring, Summarised
| Question | Answer |
|---|---|
| Brown wire | Live — bottom right, to the fuse |
| Blue wire | Neutral — bottom left |
| Green/yellow | Earth — top terminal, longest core |
| Old colours | Red = live, black = neutral, green = earth |
| Fuse for ≤700W | 3A |
| Fuse for >700W | 13A |
| Cord grip | Clamps the outer sheath, never the cores |
Expert Help in the West Midlands
Bring the appliance's rating plate — or a photo of the mystery flex you found behind the sideboard — to our trade counter on Villa Road, Birmingham. We've been decoding wiring for the region's electricians since 1975, and we'll match you to the right fuse, flex and fittings from our Wiring Accessories range while you wait.
Frequently Asked Questions
Which wire is live in a UK plug?
The brown wire (red on pre-2006 flex). It connects to the bottom-right terminal, in line with the fuse — so the fuse can cut the live supply the moment something goes wrong.
What fuse do I need for my appliance?
Check the wattage on the rating plate. Up to about 700W, fit a 3A fuse; above that, fit a 13A. Kettles, heaters and toasters are 13A; lamps, chargers and TVs are 3A.
Is it legal to wire your own plug in the UK?
Yes. Replacing a plug or fuse is basic maintenance, not notifiable electrical work. What matters is doing it properly: correct colours, correct fuse, cord grip on the sheath, and a tug test before the cover goes back on.