Introduction to Wiring and Plugs

uncletony wishes to stress that if you have any doubts in what you're doing
with Mains electricity STOP

Warning Sign

In Europe the Mains electricity supply is 230 Volts, 50Hz

The Mains supply can and does KILL

If in ANY doubt - STOP and ASK for Help

Warning Sign

Mains cable

Step 1

Select the cable with the correct current rating

  • 3 Amp - Wire size 0.5mm2 (each conductor 16 x 0.2mm) for equipment upto 700 Watts
  • 5 Amp - Wire size 0.75mm2 (each conductor 24 x 0.2mm) for equipment upto 1200 Watts
  • 13 Amp - Wire size 1.25mm2 (each conductor 40 x 0.2mm) for equipment upto 3000 Watts

Prepared Mains Cable

Step 2
Prepare the cable.

Remove cable outer sheath and trim the wires as follows:

  • BROWN wire 20mm long
  • BLUE wire 30mm long
  • GREEN wire 50mm long

Strip 12mm of insulation from each wire to reveal bare copper


Fuses for UK Mains Plug

Step 3
Select the correct Mains Fuse
  • 3 Amp (Red) for equipment upto 700 Watts
  • 5 Amp (Black) for equipment upto 1200 Watts
  • 13 Amp (Brown) for equipment upto 3000 Watts

Wired-up UK Mains Plug


Step 4
Connect the wires into the Plug as follows:

  • BROWN wire to L (Live) Terminal
  • BLUE wire to N (Neutral) Terminal
  • GREEN wire to E (Earth) Terminal

    Go Here for useful tips.

Re-assemble the plug, making sure the clamp grips the cable, but doesn't crush it.

Your completed plug should look very much like the one in this picture.



Other Mains (Power) Connectors
  • USA Plug

Many appliances are are un-grounded and use a two-wire power cord and a simple 2-pin moulded plug.

Two-pin plugs, sockets and extension cords are usually polarized - the smaller pin is the power 'hot' (live) and often brass coloured. The 'low' (neutral) side is the larger white-metal pin.

The introduction of more stringent FCC rules concerning EMC radiation and NEMA safety regulations has resulted in an increasing use of 3-pin plugs and 3-wire power cables.

USA grounded plug
Grounded Plug -
looking at the blades.

An easy way to remember polarity:

Brass pin/screw = Black wire [Hot]
White pin/screw = White wire
Green pin/screw = Green wire

Power cable - USA  Black = Live [Hot]
 White = Neutral [Cold]
 Green = Earth [Ground]

For more on US electrical stuff follow these links:

Link to Leviton Inc
Go To Tech Support
and Education Section

Link to Hubbell Electrical Catalogue (PDF file)
Viewing the catalogue
requires Acrobat Reader

  • European (Schuko or Schukostecker) Plug
Live and Neutral connections are made on the two Pins.

Looking at the Pins

The Earth connector is a metal socket moulded into the plug assembly. This socket mates with a male grounding pin which sticks out from the the wall/cable socket (receptacle).


Warning Sign

uncletony has determined that MOST Schuko plugs are wired as shown, but has occassionaly encountered plugs with the Live and Neutral reversed.

  • IEC Connector (Cable mounted Socket)
The IEC Connector comes in two 'flavours'.

IEC-Cold connectors are for use up to 1200 Watts at normal temperature (eg computer power cord, etc).

IEC-Hot are specifically constructed connectors to withstand high temperatures (eg kettles, toasters, etc).

The keyway prevents inappropriate use.


IEC - Cold cable socket
Viewed from the Sockets
IEC Cold
IEC - Hot cable socket
Viewed from the Sockets

Double Insulated

Double-Insulated symbol

Appliances that do not require an Earth connection (because the construction prevents any live metallic part from being touched) are referred to as being Double Insulated and must show this symbol.

For more on Symbols related to electrical approvals and safety
go here


Changes to UK wiring  

Pre-2004 wire colours
Pre-2004 wire colours


Post-2004 wire colours
Post-2004 wire colours









UK electric power cable colours are changing...
In March 2004 an amendment to British Standard BS 7671 ('Requirements for Electrical Installations') brings UK colour coding of electric cables into harmony with most other EU member countries.

'2 core and earth' (Twin and Earth) cable
Pre-March 2004 the UK standard for '2 core and earth' cable used in single phase (i.e. normal household) installation was:

Live = Red
Neutral = Black
Earth = Green and Yellow
(Note: the earth wire is normally a bare copper conductor within the T & E cable. The term
Green and Yellow applies to the coloured sleeving which must be fitted over the bare earth wire).

Post-March 2004 the UK standard was changed to:

Live = Brown
Neutral = Blue
Earth = Green and Yellow
sleeving (no change)

(Note: This new colour coding is the same as used for appliance flexes in the UK for many years.)


'3 core and earth' cable (eg, used for two way lighting circuits)
Pre-March 2004 the UK standard for '3 core and earth' cable used in two way lighting was blue, yellow and red with a bare copper earth.

Post-March 2004 the UK standard was changed to Grey, Black and Brown with a bare copper earth.

Why the change ?
The change is the result of international standardisation (or harmonisation) with most of Europe already using this colour coding - the new colours are sometimes referred to as 'harmonised'.

How will the change come into effect ?
The new colours came into effect on 1st April 2004. However there is a two year overlap between the old and new colour coding.

Until 31st March 2006, either the old colours or new colours may be used (but not mixed).

From 1st April 2006, the old colours will not be permissible in new installations or when making changes.

Where new colour cable is used to extend an existing 'old colour' installation before 1st April 2006, a warning notice (see below for an examplele) must be fixed at the main distribution or consumer unit of the installation.

Three Phase wiring
The Red, Blue and Yellow phase wires (and Black for Neutral) will also change colours.
Please consult the IEE website for complete details.

More information

A promotional flyer/expanatory leaflet is available in PDF format (278KB) on this IEE page: http://www.iee.org/publish/wireregs/cablecol.cfm


For more details on international voltage/frequency standards
and a country-by-country list of power connectors go here


If you wish power connectors from other countries to be included please send details to uncletony

e-mail uncletony

Return to Home Page Rev: 03-2009