Moulded plugs for unearthed, double-insulated appliances may instead have a non-conductive plastic pin (an Insulated Shutter Opening Device or ISOD) the same size and shape as an earth pin, to open the shutters. The variants use a flattened earth pin, each at a different specified rotational position. Correct polarity is established by the position of the earth pin relative to the other two pins, ensuring that the line pin is connected to the correct terminal in the socket-outlet. This method is sometimes used to allow a Europlug (with two small round pins and no earth pin) to be forced into the open line and neutral ports. An early method of sleeving the pins involving spring-loaded sleeves is described in the 1967 British Patent GB1067870. The method actually adopted is described in the 1972 British Patent GB1292991. January 1957: BS 1363:1947 Amendment 5, added clause permitting operation of shutters by simultaneous insertion of two or more pins (in addition to original method using only earth pin).

Many sockets use the original method of shutters opened by the earth pin (or plastic ISOD), longer than the other pins and hence opening the shutters before the other pins engage, alone. The insertion of non-compliant plugs may damage sockets. Alternatively, shutters may be opened by simultaneous insertion of line and neutral pins. This amended standard adds a requirement that it shall not be possible to operate a shutter by the insertion of a two-pin Europlug, and added specifications for switched adaptors amongst others. Different types of cables are used at different requirement like Coaxial cables, twisted cable pair cables, etc. The color codes on the electrical cables help to identify their purpose of usage and helps in proper operation and installation. Introduction of the Bartlane cable picture transmission system in the early 1920's reduced the time required to transport a picture across the Atlantic from more than a week to less than three hours. Some later designs require all three pins to be inserted simultaneously. Third rail current collection comes in a variety of designs. Up to 3000 volts overhead is used by DC main line systems (e.g., parts of France, Belgium and Italy) but below 1500 volts, a third rail can be used.

The line 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. When looking at the plug pins with the earth uppermost the lower left pin is live, and the lower right is neutral. The distance from any part of the line and neutral pins to the periphery of the plug base must be not less than 9.5 mm. This standard superseded BS 1363:1967. Changes include the introduction of sleeved pins on Line and Neutral, metric dimensions replacing inches, specifications added for non-rewirable plugs and portable socket-outlets. This amended standard allows switches to be incorporated into plugs, and introduced new overload tests amongst others. Adaptors which allow the use of non-BS 1363 plugs, or more than two BS 1363 plugs, must be fused. Unlike a temporary travel adaptor, conversion plugs, when closed, resemble normal plugs, although larger and squarer.

This new standard covers adaptors for use with BS 1363 socket-outlets and includes conversion adaptors (those which accept plugs of a different type), multiway adaptors (those which accept more than one plug, what is electric cable which may or may not be of a different type) and shaver adaptors. A separate standard specifying a switched version of the BS 1363 socket-outlet for use with BS 1363 plugs. Several manufacturers have made deliberately incompatible variants for use where connection with standard plugs is not acceptable. September 1995: BS 1363-3:1995 "13 A plugs socket-outlets adaptors and connection units - Part 3: Specification for adaptors" published. November 1995: BS 1363-4:1995 "13 A plugs socket-outlets adaptors and connection units - Part 4: Specification for 13 A fused connection units switched and unswitched" published. June 1947: BS 1363:1947 "Fused-Plugs and Shuttered Socket-Outlets" published. 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. Fuses are mechanically interchangeable; it is up to the end-user or appliance manufacturer to install the appropriate rating fuse. An example would be Class II appliances from mainland Europe which are fitted with moulded europlugs.