BS 1363 is a British Standard for AC power plugs and sockets in the United Kingdom, rated for up to 250 V and 13 A. These rectangular 3-pin plugs correspond to Type G according to the IEC. Distinctive characteristics of the system are shutters on the and neutral socket holes, and a user replaceable fuse in the plug.
The BS 1363 is a one plug solution being an alternative to the older round-pinned, BS 546 socket-outlet family of four differing non- interchangeable socket-outlet types. The BS 1363 replaced the 2A, 5A and 15A of the four BS 546 socket-outlet types by inserting a fuse of the appropriate amperage rating between 1A and 13A into the plug. It became the dominant socket-outlet in the United Kingdom for most domestic uses also being adopted in many of its current and former overseas territories. The Type G plug and socket is also primarily used in a number of other countries around the world, and BS 1363 is adapted into equivalent standards including national Irish (I.S. 401), Malaysian (MS 589) and Saudi Arabian (SASO 2203) ones. The sockets are not directly compatible with any of the European plugs (CEE 7), nor with the British shaver plug.
Ratings BS 1363 plugs and sockets are rated for use at a maximum of 250 V AC and 13 A. The exception is non-rewirable plugs which have a current rating according to the type of cable connected to and the fuse fitted. The rating must be marked on the plug, and in the case of non-rewirable plugs the marking must be the value of the fuse fitted by the plug manufacturer in accordance with table 2 of the standard.BS 1363-1:1995+A4:2012, cl. 7.1 f Typical ratings for non-rewirable plugs are 3 A, 5 A, 10 A and 13 A.Volex company website (retrieved 7 March 2013) Plugs
These British plugs are described in part 1 of the specification (BS 1363-1 Rewirable and non-rewirable 13 A fused plugs). A BS 1363 plug has two horizontal, rectangular pins for and neutral, and above these pins, a larger, vertical pin for an earth connection. Both line and neutral carry current and are defined as live parts.Brian Scaddan (2011), 17th Edition IEE Wiring Regulations: Explained and Illustrated, Routledge, p. 18 (retrieved 6 March 2013 from Google Books) The earth pin also serves to operate the basic shutter mechanism used in many sockets. Correct polarity is established by the position of the earth pin relative to the other two pins, ensuring that the pin is connected to the correct terminal in the socket-outlet.
Moulded plugs for unearthed, double-insulated appliances may instead have a non-conductive plastic pin (an Insulated Shutter Opening Device or ISOD, sometimes called a dummy pin) the same size and shape as an earth pin, to open the shutters. When looking at the plug pins with the earth uppermost the lower left pin is , and the lower right is neutral.
UK consumer protection legislation requires that most domestic electrical goods sold must be provided with fitted plugs to BS 1363-1. These are usually, but not necessarily, non-rewirable. Rewirable plugs for hand-wiring with a screwdriver are commonly available and must be provided with instructions.BS 1363-1:2016+A1:2018, cl. 7.4
Nominal dimensions BS 1363-1 specifies the dimensions of plug pins and their disposition with respect to each other in precise, absolute terms.BS 1363-1:1995+A4:2012, fig. 4a The and neutral pins have a rectangular cross section 6.4 mm by 4.0 mm, 17.7 mm long and with centres 22.2 mm apart. The protective-earth pin is a rectangular cross section 8.0 mm by 4.0 mm, 22.3 mm long and with a centre line 22.2 mm from the line/neutral pin centre line. The dimensions were originally specified in decimal inches with asymmetric tolerances and redefined as minimum and maximum metric dimensions in BS 1363:1984.
Dimensions are chosen to provide safe clearance to live parts. The distance from any part of the and neutral pins to the periphery of the plug base must be not less than 9.5 mm. This ensures that nothing can be inserted alongside a pin when the plug is in use and helps keep fingers away from the pins. The longer earth pin ensures that the earth path is connected before the live pins, and that it remains connected until after the live pins are disconnected. The earth pin is too large to be inserted into the or neutral sockets by mistake.
Pin insulation
Initially, BS 1363 did not require the and neutral pins to have insulating sleeves. Plugs made to the recent revisions of the standard have insulated sleeves to prevent finger contact with pins, and also to stop metal objects (for example, fallen window blind slats) from becoming live if lodged between the wall and a partly pulled out plug. The length of the sleeves prevents any live contacts from being exposed while the plug is being inserted or removed. An early method of sleeving the pins involving spring-loaded sleeves is described in the 1967 British Patent GB1067870.British Patent GB1067870 (Spring loaded pin sleeves) The method actually adopted is described in the 1972 British Patent GB1292991.British Patent GB1292991 (Fixed pin sleeves) Plugs with such pins were available in the 1970s; a Southern Electricity/RoSPA safety pamphlet from 1978 encourages their use."Safety in the home", Southern Electricity & RoSPA | 00-980-05 | October 1978 Sleeved pins became required by the standard in 1984.
Fuses (BS 1362)
There are two common misconceptions about the purpose of the fuse in a BS 1363 plug: one is that it protects the appliance connected to the plug, and the other is that it protects against overloading. In fact the fuse is there to protect the flexible cord between the plug and the appliance under fault conditionsGeoffrey Stokes (2008), A Practical Guide to the Wiring Regulations, John Wiley & Sons, p.65 (retrieved 24 February 2014 from Google Books)Cook, Paul, "Commentary on IEE Wiring Regulations 16th Edition (BS 7671:2001)", Cl 6.8, IET 2002 (typical British ring circuits can deliver more current than appliance flexible power cords can handle).
BS 1363 plugs are required to carry a cartridge fuse, which must conform to BS 1362. Post-War Building Studies No. 11, Electrical Installations included the recommendation that "Provision should be made in the plug for the accommodation of a cartridge type of fuse for 13 amps., and alternatively, for 3 amps. Fuses of these ratings should be interchangeable and be readily identified."Post-War Building Studies No. 11 Electrical Installations, Appendix "Supplementary report on a recommended new standard socket-outlet and plug", page 88, para x., HMSO, London 1944 The original BS 1363:1947 specified fuse ratings of 3 A, 7 A and 13 A.Journal of the Institution of Electrical Engineers, Volume: 94, Issue: 81, page 390, September 1947 The current version of the fuse standard, BS 1362:1973, allows any fuse rating up to 13 A, with 3 A (coloured red) and 13 A (coloured brown) as the preferred (but not mandated) values when used in a plug. All other ratings are to be coloured black. Most common in consumer retail outlets are fuses rated 3, 5 and 13 A; Professional suppliers also commonly stock fuses rated 1, 2, 7, and 10 A.
Fuses are mechanically interchangeable; it is up to the end-user or appliance manufacturer to install the appropriate rating fuse. More appropriate lower-capacity fuses are now supplied with some plugs instead.
BS 1362 specifies sand-filled ceramic-bodied cylindrical fuses, with dimensions of in length, with two metallic end caps of diameter and roughly long. The standard specifies breaking time versus current characteristics only for 3 A or 13 A fuses. For 3 A fuses: 0.02–80 s at 9 A, < 0.1 s at 20 A and < 0.03 s at 30 A. For 13 A fuses: 1–400 s at 30 A, 0.1–20 s at 50 A and 0.01–0.2 s at 100 A.
BS 1363-4 13 A fused connection units switched and unswitched Switched and unswitched fused connection units, without sockets, use BS 1362 fuses for connection of permanently wired appliances to a socket-outlet circuit. They are also used in other situations where a fuse or switch (or both) is required, such as when feeding lighting off a socket-outlet circuit, to protect spurs off a ring circuit with more than one socket-outlet, and sometimes to switch feeds to otherwise concealed sockets for kitchen appliances.
Other safety features
The plug sides are shaped to improve grip and make it easier to remove the plug from a socket-outlet.BS 1363-1:1995+A4:2012, cl. 12.13 The plug is polarised, so that the fuse is in the side of the supply.BS 1363-1:1995+A4:2012, cl. 12.4 The flexible cord always enters the plug from the bottom, discouraging removal by tugging on the cable, which can damage the cable.BS 1363-1:1995+A4:2012, cl. 19.1 Rewireable plugs must be designed so that they can be wired in a manner which prevents strain to the earth connection before the line and neutral connection in the event of failure of the cord anchorage.BS 1363-1:1995+A4:2012, cl. 11.8
Counterfeits and non-standard plugs Plugs which do not meet BS 1363 often find their way into the UK. Some of these are legal in the country they are manufactured in, but do not meet BS 1363 – these can be brought into the UK by unsuspecting travellers, or people purchasing electrical goods online. They can also be purchased through many UK electrical component distributors. There are also counterfeit plugs which appear to meet the standards (and are marked as such) but do not in fact comply. Legislation was introduced, with the last revision in 1994, to require plugs sold to meet the technical standard. Counterfeit products are regularly seized when found, to enforce the safety standards and to protect the approval marks and trademarks of imitated manufacturers.Wiring Accessories & Counterfeiting The pressure group PlugSafePlugSafe website reported in March 2014 that since August 2011 "thousands" of listings of products including illegal plugs had been removed from the UK sections of the websites eBay and Amazon Marketplace. The UK Electrical Safety Council expressed shock at the magnitude of the problem and published a video showing a plug exploding due to a counterfeit BS 1362 fuse. The Institution of Engineering and Technology also published information on the extent of the problem with online retailers, many advertising replacement cord sets, mobile device chargers, and travel adaptors fraudulently marked BS 1363, and mentioning the same sites."Buyer Beware, Many plugs and chargers – often obtained online – pose a serious risk to users", Wiring Matters, Summer 2013, p. 14. "... the main problem is with online stores such as eBay and amazon marketplace"
Sockets
BS 1363 sockets are described in part 2 of the specification (BS 1363-2 13 A switched and unswitched socket-outlets). These sockets are commonly supplied with integral switches as a convenience, but switches are optional and did not form part of BS 1363 until 1967.