This requirement for a new system of plugs and sockets led to the publishing in 1947 of the:
British Standard 1363 : 1947 FUSED PLUGS AND SHUTTERED SOCKET OUTLETS
This included the requirement that “The construction of the socket outlet shall be such that when the plug is withdrawn the current-carrying socket-contacts are automatically screened by shutters not operated solely by the current carrying plug-pins.”
Thus the shuttered socket which is still in use today was born. The method of opening the shutters was, and still is in most designs, the insertion of the earth pin. In 1957 Clause 5 was amended to “The construction of the socket outlet shall be such that when a plug is withdrawn from it the current-carrying socket-contacts are automatically screened by shutters. The shutters shall be operated either by the insertion of the earthing plug-pin or by the insertion of any two or more pins of the plug....” This change allowed the method of opening the shutters which is used in sockets manufactured by Mk.
The introduction story is told more fully in an article published by the IET. It is of interest to note that the concept of automatic shutters being used in UK sockets for protection dates back to at least 1927! (GB Patent 294 689)
Several generations of professional electrical engineers have ensured that children are not at risk from power sockets, that effort is now put at risk through the ignorant promotion and use of devices which are not tested against any electrical standards, and appear to be designed by toy manufacturers!
BS 1363 in combination with The Plugs & Sockets etc. (Safety) Regulations (1994) and the IEE (IET) Wiring Regulations provide an excellent framework with legal backing to ensure that electrical installations in the UK are safe and do not present a threat to children. However, there are no regulations in force which are specific to socket covers, this means that when a socket cover is used you can no longer assume that you have safe sockets! The General Safety Regulations require that socket covers be non-toxic and do not present a swallowing hazard to children, but that’s about all.
There is a report prepared by the Swedish National Testing and Research Institute for ANEC (European Association for Consumer Representation in Standardisation). The report, available on-line, is called “Child protective products – protective function of socket protectors, hob guards, locks and locking devices” The author of this report sets out the basic requirements and proposed test methods which should be adopted by EU Member States to ensure that child safety devices are effective and safe.
The ANEC report appears to address most of the issues which concern FatallyFlawed, in particular para 3.4: “the protective function should not be reduced through normal or foreseeable use and misuse. The material should be suitable to reasonably foreseeable conditions of use.” This addresses our fundamental concern affecting all socket covers, that of inverted insertion by children. The current terms of reference under which UK Trading Standards operate appear to preclude taking into account dangers caused by misuse, but how do you tell a small child that they are safe only if they do not misuse a safety device?
The ANEC report’s Appendix B para 6.4.2 recommends that insulation tests are carried out on socket covers. The situation pertaining currently in the UK which permits replacing the fully tested insulation properties of the shutters of a BS 1363 socket with an untested cover can only be described as official lunacy.
The ANEC report’s Appendix B para 6.4.5 recommends the following method for testing socket covers for access to live parts: “Use test probe 17 (Ø 0,5 mm test wire) of EN 61032 :1998 in order to see if it is possible to get in contact with live parts by means of the test probe. The probe shall be applied, on all accessible surfaces and openings of the socket protector and between the socket protector and the socket.” The tests conducted by FatallyFlawed conform to this recommendation and demonstrate that socket covers sold by Mothercare, IKEA, Clippasafe, Boots and John Lewis amongst others are unsafe in normal use because they allow the insertion of pins, needles and paper clips etc.
Of course, there are many other requirements and tests recommended. in the report, including the subject of how children can be prevented from removing safety devices. The concerns of FatallyFlawed about the ease of withdrawal of plug-in socket covers are largely related to the fact that socket covers do not conform to the pin dimensions specified in BS 1363.
The design of devices which have to work together even when they come from different manufacturers (“interoperability” is the technical term) is a complicated and demanding process. If you study BS 1363 you will see that the really critical dimensions are those of the plug, and these are tightly controlled. When a socket is designed it must clearly be certain that it will work properly and safely when it is both empty, and when a plug is inserted into it. The Plugs and Sockets etc. (Safety) Regulations 1994 (Statutory Instrument 1994 No. 1768) ensure that all domestic power sockets and corresponding plugs comply with the relevant standards. Unfortunately these regulations do not apply to socket covers, (for which there is no British Standard) so there is no way to ensure that covers are properly and safely designed.
There are several ways in which socket cover designers ignore the critical dimensions specified in BS 1363. To ensure that there is no possibility of accessing live contacts when a plug is inserted into a socket, BS 1363 requires the live and neutral pins to be at least 9.5 mm from the periphery of the plug, we have found only one socket cover on current sale which meets that requirement! (The Mothercare/IKEA type being the worst at less than 1 mm.) The other critical dimensions concern the pins themselves. We have not found a single cover which complies with the specifications for the length of the live and neutral pins, and this means that the security with which the plug is held in the socket is completely unpredictable, as explained below.
In our video we demonstrate the tendency of some covers to “pop out” of some sockets. We believe that the main reason for this is that plug-in covers always have dummy live and neutral pins which are shorter than the real pins specified in BS 1363 (minimum length 17.2 mm). We have yet to find a socket cover which has pins longer than 16.7 mm and the shortest we have tested is only 11.3 mm. The permitted minimum distance between the surface of a socket faceplate and the line/neutral contacts is 9.6 mm, and the maximum is 12.2 mm. From this it is quite clear that covers with pins of 11.3 mm are not going to engage in a meaningful way with the contacts of any socket, and this means that the line/neutral pins of those covers contribute nothing to holding the cover in place. However, those we are particularly concerned about are in the length range 14 mm to 17 mm. It is in this range that you will find the two most popular socket cover types: IKEA/Mothercare type at 14.2 mm (12.7 mm to the chamfer) and the Clippasafe/Boots/John Lewis type at 16.6 mm (14.3 mm to chamfer). It is immediately obvious that when these are inserted in a socket which has the maximum faceplate to contact distance of 12.2 mm there will be no contact with the flat surface of the pins unless the contacts themselves are unshaped. The socket shown in our demonstration is branded Tenby and has a faceplate to contact distance of 12.1 mm, but the distance from the faceplate to the point where the flat of the pin is tangential to the curve of the contact (ie, where there is no longer any back thrust on the pin) is 14.8 mm, thus it can be seen that neither of the above types of socket cover can achieve a stable relationship with the contacts and hence they pop out to the point where there is insufficient pressure between pin and contact to generate further back thrust.
We have noted that the Clippasafe/Boots/John Lewis pattern tends not to “pop out” of MK sockets, but the shorter pinned Mothercare/IKEA pattern still does.
FatallyFlawed does not claim that the cover types mentioned above will always “pop out”, but that their behaviour is unpredictable because sockets are designed to reliably mate only with properly dimensioned pins. We believe that it is utterly irresponsible of socket cover manufacturers to ignore such basic considerations when they design their products.
Experience in other countries
Most countries do not have inherently safe sockets, hence the reason that socket covers were introduced as a next best solution. Covers work best in recessed sockets such as those used in Sweden, Germany and France (pictured left). The recess in the sockets makes it much more difficult for a child to remove a cover.
Socket covers do not work well in flush sockets such as those used here in the UK, and in the US. FatallyFlawed is not aware of any comprehensive research into socket cover use in the UK, other than our own. Which? undertook limited testing of socket covers in 2009, but have since withdrawn the results from their website. There is more comprehensive American research available because, in the absence of the universal use of safe sockets, child fatalities due to poking objects into sockets are significant. Information on the issue is available from a major US insurance company State Farm. A newspaper article includes some of the results of research undertaken at Temple University in 1997 which indicated that babies and small children do not find the removal of socket covers difficult. Various gadgets have been incorporated into US socket covers, with little success, the one shown in the video “Joey is a socket cover ninja!” is one of these. As a result there has been a move towards the use of shuttered sockets in the US, although it is not planned as a universal solution as we have in the UK. This US information website makes interesting reading, as does this fact sheet about their new shuttered sockets. Please review the US information, and then reflect that in the UK we have been world leaders in this area since the 1920s!
The bottom line is:
Safety is designed into UK sockets - plug in covers reduce safety!