There are several differences with and noticeable characteristics of electrical fuses in the United Kingdom. These include the colour systems used for wiring plugs, the standard amp ratings, and the terminology and the legislation used. There are also some variations of the traditional replaceable fuse-based circuit board.
Definition of "Fuse"
The United Kingdom generally uses the term fuse in the same sense as in North America, namely the replaceable section. This is in contrast to the International Electrotechnical Commission which uses fuse to refer to the entire unit, comprising the replaceable fuse and the fixed fuse holder. In the UK this holder is known as a fuse link.
The Plugs and Sockets etc (Safety) Regulations 1994 covers the supply of electrical fuses. This is a statutory instrument meaning that the government introduced the rule but it has the same legal force as an Act of Parliament.
This law requires that in usual circumstances a plug must conform to British Standard 1363 and contain a fuse link conforming to British Standard 1362.
Some older properties in the UK have circuit boards which use fuse wire rather than replaceable fuses. This involves tightening a stretch of wire around two screws to complete the circuit. Fuse wire is not used in plugs as it would breach the 1994 regulations.
New properties may have a trip-switch circuit board which does not have replaceable fuses. This is known in North American as a ground fault circuit interrupter. Rather than having to replace a fuse after a circuit problem, the user can simply flick a switch back into the on position.
There have been two major changes to the colouring system used in the United Kingdom for fused plugs. Until 1977 the colours were green for the earth wire, black for the neutral wire and red for the live wire. In 1977 this changes to green and yellow stripes for the earth wire, with black/neutral and red/live still used. This remains the system used in the majority of properties.
Since 2004, new plugs have used green/yellow for earth, blue for neutral and brown for live. This is in line with other European Union countries.
One advantage of this colour system is that the first two letters make it easy to remember that the blue (neutral) wire goes on the bottom left terminal and the brown (live) wire goes on the bottom right terminal, leaving the green and yellow wire on the top terminal.
UK fuses come in three standard current ratings: 3 amps, 5 amps and 13 amps. The correct fuse to use with any electrical appliance is the lowest rating which exceeds the current needed for the appliance.