Museum of Plugs and Sockets logo, small BS 372 : 1930 Part I
not earthed plugs and sockets
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BS 372 Part 1, 5A socket
BS 372 Part 1, GEC 5A plug
Clix 2-pin 10A plug
BS 372 Part 1, Clix 15A plug

Clix 2-pin plug with grub screw for cord fixation
Clix system for wire attachment to plug pins
BS372-like 5A 2pin plugs

1 BS 372 Part I, Bakelite, surface mount 2-pin 5A socket. U.K. Patent No. 473440 for "Improvement in and relating to sockets and socket mountings for electrical plug connections", granted to Ward & Goldstone in 1937 is indicated.   {JM}
2 BS 372 Part I plug, rated at 5A - 250V. Such flat top models existed for 2A, 5A and 15A and were made in England by General Electrical Company in the 1930s to (at least) 1950s. The Standard refers to "Two-pin Side-entry Wall Plugs and Sockets for Domestic Purposes", as the GEC plug shows.   {DP}
3 Two pin 10A plug made by Clix*. A rating of 10 A is an uncommon 'relict' of the old Union gauge (see historic note below). It did not comply to BS 73 and following BS 372. These standards described 2A, 5A, 15A and 30A only. Plug dating: possibly 1950s.
* Clix plugs had an unique type of wire attachment; image no. 6 shows the principle in detail.
4 CLIX BS 372 Part I plug, rated at 15A - 250V. The plug has a cord side entry, comparable to plug no. 5. Image nos 1 to 4 are shown in proportion to each other.   {GP}
5 BS 372 Part I, 5A plug, CLIX type 5/2/B. Flex cord is gripped by a grub screw (made of wood), an improvement that has been patented by Charles Reginald Cook (Chesworth, Horsham, Sussex). Patent no. GB426943, granted on December 28, 1933. The patented CLIX wire fixation system is show in detail in image no. 6.   {MS}
6 CLIX type 5A plug, which allows the attachments of wires without using any tools.
The principle of wiring a CLIX plug: [1] unscrew cap; [2] release pins by pressing them inwards; [3] put wire through the loop of a pin; [4] insert pin with wire into the base of the plug and press the pin fully down; [5] screw the cap tightly down (this is essential to keep the wires in a safely locked position !).
The wire fixation system has been patented by four patents (GB371404, GB371418, GB403448, GB457113), granted between April 18, 1932 and October 4, 1935 to C.R. Cook.   {RM}

Note that the flex cable entry is opposite the plug face. Although top entry plugs were very common in the UK, they do not fully comply with BS 372 Part I or the preceding BS 73. British Standard require that the cord enters at the side (note given by David Peacock).
7 Two 2-pin plugs. The plug at left shows the text: 5A.250V. B.S.GAUGE and has been made by General Electric Company. Pin spacing (16.7 mm) and diameter of pins (5.1 mm) are in accordance with BS 372 Part I, but pins are shorter: 13.3-13.5 mm, rather than 15.9 mm.   {ASw}

In 1970 BS 372 was withdrawn in favour of BS 4573 that defines two-pin reversible plugs and shaver socket-outlets. Any other 2-pin plugs were no longer permitted. Shaver plugs must have insulated pin sleeves.
Characteristics of 2-pin plugs
current rating
pin diameter
pin length
pin spacing
  5A (plug no. 2) 5.1 mm
15.9 mm
16.7 mm
10A (plug no. 3)
5.0 mm 19.6 mm 19.5 mm
15A (plug no. 4)
7.0 mm 20.6 mm 22.3 mm


MK Electric BS 372 Part 1 5A socket with switch BS372 5A 2 pin Coltone multiplug BS372 5A 2pin Goltone multiplug top BS372 5A 2pin multiplug

Grelco BS 372 Part 1, 2-pin dual plug with outlets for 5A and 2A Grelco BS 372 Part 1, 2-pin dual plug with outlets for 5A and 2A
BS1363 multi-purpose plug

8 Surface mount 5A BS 372 Part 1 socket with switch. Manufacturer: MK Electric. Dating: 1970s - '80s.   {DH}
9, 10
Bakelite 2-pin multi-plugs. An appealing, classic design made by Ward & Goldstone, who used the trademark Goltone. The inscription on top warns that the maximum load may not exceed 5A, 250V.   {ASw}
11 White plastic 3-way 5A, 2-pin multi-plug. Brand name: Clang.   {ASw}
12, 13
BS 372 Part I, 5A multi-plug with outlets for 5A and 2A BS 372 Part I plugs. Made in England by Grelco.   {DP}
14 3A BS 1363 multi-plug, 'Empire Made' by Livia Electrical (model 5067). Besides a single BS 1363 outlet (with shutters) it also has two outlets for 5A 2-pin plugs. In the 1970s and '80s it was quite common to have 2-pin plugs on small appliances. The 2-pin outlets were convenient when people moved house or had their house rewired, but didn't like to change the plug of some lamps etc.   {DF}


Notes about history of British non-earthed plugs

Before electrical plugs were covered by a British Standard, there was a variety of proprietary plugs.

A General Electric Company catalog for 1911 lists 2 pin plugs for domestic use rated at 3A (
"Midget"), 5A ("Standard") and 10A ("Union"). It had evidently been found that the "Union" plug could handle 15A, so it was sometimes referred to in old books as 10/15A. Plugs rated at 25A and 50A were also available. Earthed plugs were only available for industrial and Naval use.

BS 73:1915 was the first British standard for 2-pin non-earthed plugs and sockets. It was in 1930 replaced by BS 372 Part I.

The 2 pin "Midget" (3A, later redesigned to 2A) and "Union" plug (10A) are no longer produced.

GEC Standard Gauge socket and plug (1911)

The only plug with two round pins that is still used in the UK is the shaver plug (BS 4573). The model is derived from the 5A "Standard" plug, but restyled and downgraded to 0.2 A.

Both BS 372 and its predecessor BS 73 specified side entry for the cables (see plug no. 2). Plug nos. 3 and 6 shown above do not conform to the standard, although they 
will fit into a BS socket. Not having a cable side entry is probably why they are not marked as BS 372. In the 1930s there was no law demanding that plugs met the standards, as there is now.

Note that BS 546:1934 (and later versions) does not mention any non-earthed plugs and sockets. BS 372:1930, the standard that preceded BS 546 consisted of two parts. Part I about 2-pin plugs and Part II about earthed 3-pin plugs (now covered by BS 546).

 Details are kindly provided by Ronald Camp and David Peacock.

From a 1911 G.E.C. catalog:   Two pin wall plates

Wall plates have admittedly to withstand far more severe usage and rougher treatment than any other electrical accessory. We have, therefore, devoted the greatest attention to producing a standard line of plugs which are immune from weaknesses common to most existing types.

All parts are interchangeable and made to limit gauges. The socket tubes are fixed to the terminal plates by a new and improved method, giving additional contact surface and ensuring permanent and perfect contact under all conditions. The terminals are of ample dimensions and the complete plugs guaranteed to permanently carry currents far in excess of their rated capacities.

Examples of old 2-pin plugs and sockets are shown in the gallery of classic material used in South Africa.


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