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9 Easy Steps to Wiring a Plug Correctly and Safely

Eugene is a qualified control/instrumentation engineer Bsc (Eng) and has worked as a developer of electronics & software for SCADA systems.

How to Wire a UK Plug

This guide shows you how to specifically wire a UK plug to a domestic appliance. However the same basic principles of wiring a BS1363 type plug can be applied to plugs from other countries, the main difference being that the colour-coding of wiring is different.

How to wire a plug. This is a UK style, BS1363 plug with integral 13 amp fuse.

How to wire a plug. This is a UK style, BS1363 plug with integral 13 amp fuse.

British BS1363 Standard Plug (Type G Plug)

The BS1363 standard 3-pin plug is used in the UK (England, Wales, Scotland and Northern Ireland), the Republic of Ireland, Malaysia, Saudi Arabia and several other countries. It's categorised as plug type G by the International Electrotechnical Commission. The plug incorporates several safety features, including a fuse to protect the power cord and equipment and also shrouded pins to prevent inadvertent finger contact with the live or neutral pins during insertion and removal. By law in the EU, new appliances must be fitted with a non re-wireable plug, however occasionally you may need to fit a plug to an older appliance.

What Are the Steps to Wiring a UK Plug?

  1. Remove the cover from the plug
  2. Remove the outer sheath from the flex to expose the inner cores. Take care not to damage the inner cores while removing the sheath
  3. Shorten the brown wire
  4. Remove the insulation from the ends of the wires
  5. Twist the strands of wire together
  6. Feed the wires under the strain relief into the plug
  7. Double over the ends of the wires
  8. Insert the brown wire into the live (L) screw terminal and screw tight
  9. Insert the green/yellow wire into the earth (E) screw terminal and screw tight
  10. Insert the blue wire into the neutral (N) screw terminal and screw tight
  11. Tighten the screws of the strain relief over the sheath (not the cores!) of the flex
  12. Check all wires are packed away neatly so they can't be caught by the cover
  13. Screw the cover back onto the plug

↓ Scroll down for step-by-step instructions and photos ↓

The Safest Plug in the World?

The BS1363 Plug is undoubtedly the safest plug in the world and has the following features:

  • Fused: The function of the fuse is to protect the power cord/flex from overheating and possibly catching fire. In a short circuit situation, a distribution circuit will supply current greater than a power cord/flex is capable of carrying (possibly tens of thousands of amps). The fuse in the plug will blow to protect the cord and may also protect wiring/components within an appliance. A fuse will also blow when more moderate overloads occur (e.g. attempting to power too many appliances from an extension reel or multi-gang socket strip)
  • Insulated Pins: This protects inadvertent contact with live pins during insertion and removal of the plug
  • Shuttered Outlets on Sockets: This prevents children from inserting pins, nails or other metal items into socket outlets
  • Polarized: The plug cannot be inserted upside down, reversing the live and neutral
  • Long Earth Pin: which ensures that appliances are earthed during plug insertion, before the two power pins make contact
  • Grips: at the edges of the plug to facilitate easier removal
  • The Flex: exits from the bottom of the plug to discourage removal by pulling on the flex
3-Pin BS1363 Plug as used in the UK and Ireland

3-Pin BS1363 Plug as used in the UK and Ireland

Wiring Colours in the EU

EU wiring colours and old style UK colours

EU wiring colours and old style UK colours

Three core flex. Live is brown, neutral is blue and earth is green/yellow.

Three core flex. Live is brown, neutral is blue and earth is green/yellow.

Doubly Insulated or Plastic Cased Appliances

Metal cased appliances normally have a three core flex attached. However, some appliances either have plastic, non-conductive casings or are doubly insulated. A double insulated appliance has a casing which although it may still be metal, is sufficiently separated and insulated from internal live parts that there is no danger of it becoming live. These appliances are not earthed and only have a brown and blue core in their flex, i.e. no earth.

Double-insulated appliances are either marked "double insulated" or more usually the symbol below is printed on the info label.

Double insulated appliances are marked with this symbol

Double insulated appliances are marked with this symbol

Parts of a Power Plug

Inside a Plug

Screw terminals are provided inside a plug for connection of the wires of a power cord (flex). A plug has 3 pins, live, neutral and earth as shown below. The terminals are clearly marked with the letters "L", "N" and "E".

Live and Neutral

These 2 pins carry power to the appliance

Earth

Under normal conditions, no current flows through this pin. However in the event of a fault in an appliance causing the metal casing to become live, this pin acts as a "bypass", shunting current away from the user. This trips the RCD and/or MCB at the electrical panel, shutting off power. The fuse in the plug may also blow (although the RCD may trip before this occurs). The earth pin also pushes open the safety shutters covering the live and neutral entry holes in a socket outlet when the plug is inserted.

When wiring a plug, it is essential to tighten the screws firmly down onto the bared wires of each conductor. This prevents arcing, overheating and potential fire.

Live, neutral and earth terminals in a plug are marked L, N and E respectively

Live, neutral and earth terminals in a plug are marked L, N and E respectively

Fuse

A BS1363 plug is also fitted as standard with a ceramic, high breaking capacity (HBC) fuse. This protects the power cord and also the connected appliance from overload due to a fault. Plugs are usually supplied as standard with a 13A fuse. This is the maximum current that the plug can supply, and if an appliance tries to draw in excess of this current, the fuse will eventually blow. Fuses don't instantly blow once their current rating is exceeded. Instead they have a characteristic such that large overloads (e.g. due to a short circuit) will cause the fuse to blow in fractions of a second, whereas small over currents could take minutes to blow the fuse.
13A is equivalent to a load of almost 3kW at 230 volts, 50 Hertz (Hz), the EU standardised voltage and frequency.

For more info on volts, watts and amps, see this guide:

What Is Electricity? Understanding Volts, Amps, Watts, Ohms, AC and DC

WARNING!!

Fuses should be replaced by BS1362 standard ceramic types. These fuses have a ceramic body which can withstand the likely high current (potentially > 1000A) and energy dissipated as heat during a fault. Fuses shouldn't be replaced by types with glass bodies which can rupture.

If a lower powered appliance is connected to a plug, the fuse should be replaced by a lower rating fuse to suit the cord and appliance. 3A and 5A fuses are widely available corresponding to about 700W and 1150 watt respectively.

Strain Relief

A strain relief clamp or cable grip is also provided, this must be screwed down onto the outer sheath or insulation of a cable, not the inner cores. Strain relief prevents tension on the cord during normal use from pulling wires out of the screw terminals.

Screw terminals in a plug

Screw terminals in a plug

How to Wire a British Plug

Steps 1 to 9

Tools Required

You will need:

  1. A flat bladed screwdriver. A phase tester is ideal and is a useful tool to have in your home toolbox. It has an internal neon bulb which can be used for detecting the presence of high voltage at socket or lighting outlets
  2. A wire snips (side cutters). You could also probably use a scissors
  3. A sharp knife
Snips, screwdriver and knife

Snips, screwdriver and knife

Step 1: Remove the Outer Sheath of the Power Cord

About 5cm or 2 inches of the sheath or outer insulation of the power cord must be removed. It is very important not to damage the insulation of the inner cores. You can snip down along the sheath if you have a snipe nose snips, alternatively score the sheath with the knife. Again you must be careful not to cut right through.

Sheath of power cord needs to be removed

Sheath of power cord needs to be removed

One way to remove the sheath is to snip down along the cable......

One way to remove the sheath is to snip down along the cable......

.........alternatively, score the outer sheath with a knife, taking care not to cut all the way through

.........alternatively, score the outer sheath with a knife, taking care not to cut all the way through

Bending the flex all round should break or weaken  the insulation

Bending the flex all round should break or weaken the insulation

Pull off the section of sheath

Pull off the section of sheath

Step 2: Shorten the Live (Brown) Wire

Shorten the live wire

Shorten the live wire

Step 3: Remove the Insulation from the Inner Cores

Remove the insulation from each conductor or core of the flex, about 10mm or just less than half an inch should be fine. You can either do this with a knife or use the snips. A snips is perfectly good as a wire stripper. With a bit of practice, all you need to do is grip the conductor, while cutting slightly through the insulation, and pull. Try this on some scrap flex first. Whichever way you bare the insulation, it's important to avoid breaking any strands of the copper conductor.

Use a knife, wire strippers or snips to strip about 12mm of insulation

Use a knife, wire strippers or snips to strip about 12mm of insulation

Bared conductors

Bared conductors

Step 4: Twist the Strands and Double Them Over

Twist the strands of each core of the flex and double them over. This keeps them together and stops them spreading out when the terminal screws are tightened. Doubling over the ends also ensures the screw has more wire to tighten down on. This is particularly important if the flex is light gage, in which case the screw may push the conductor out of the away as it is tightened, and only catch the edge of it.

Twist the stranded copper wire

Twist the stranded copper wire

Double over the ends of the wire

Double over the ends of the wire

Choosing a Snips

Side cutters are available for cutting varying gages of cable. I have used an Xcelite side cutters for over twenty years. The high mechanical advantage of long handles and short jaws means that they can easily snip through light to medium gage wire used in electronics. Jaws are closely spaced when closed and this is important for cleanly cutting very fine wire.

Side cutters (wire snips)

Side cutters (wire snips)

Step 5: Loosen the Screws on the Strain Relief (Cable Grip)

The strain relief on the plug  is held by two screws

The strain relief on the plug is held by two screws

wiring-a-uk-plug

Step 6: Feed the Brown Wire into the L (Live) Terminal

Feed the flex underneath the strain relief and push the strands of the brown wire into the terminal. It is easier to do this if you remove the fuse and terminal from the plug

Feed the flex underneath the strain relief and push the strands of the brown wire into the terminal. It is easier to do this if you remove the fuse and terminal from the plug

Step 7: Connect the Green/Yellow Earth Wire into the E (Earth) terminal

Some appliances don't have an earth wire in their flex

Some appliances don't have an earth wire in their flex

Make Sure the Wires Are Caught by the Screw

To avoid arcing, overheating, and in extreme cases a  potential fire, it's essential to tighten screws.

To avoid arcing, overheating, and in extreme cases a potential fire, it's essential to tighten screws.

Step 8: Finally Connect the Blue Wire to the N (Neutral) Terminal

Full wired plug - Make sure all the wires are neatly packed away so that they don't get caught by the cover or the cover fixing screw

Full wired plug - Make sure all the wires are neatly packed away so that they don't get caught by the cover or the cover fixing screw

Step 9: Tighten the Strain Relief and Replace the Cover

The two strain relief screws must be tightened to secure the flex.

The two strain relief screws must be tightened to secure the flex.

Checking the Fuse in a Plug

You can check whether the fuse in a plug is ok using a multimeter. In fact, it's a good idea to have one of these in your home toolkit if you do any basic DIY. Check out my guide to using a multimeter here: How to Use a Digital Multimeter to Measure Current, Voltage and Resistance

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: A building is being supplied with power at 220v. The load consists of 300 lamps of 60w each and 100 fans of 40w each find (i) the total loads in kilowatts (ii) the current taken by the load ?

Answer: (i) The total load is 300 x 60 + 100 x 40 = 22,000 watts or 22 kW

(ii) To find the current, divide the load in watts by the voltage

So

Current is 22,000 / 220 = 100 amps

There's lots more examples like this on my other article here:

https://dengarden.com/appliances/Watts-Amps-Kilowa...

© 2014 Eugene Brennan

Comments

Pepenaldo panana on June 23, 2020:

what i wanted thanks

Gift on May 14, 2020:

Thanks

kudzaiishe on October 16, 2017:

tank you just what i needed