Museum of Plugs and Sockets logo, small Classic continental European
not earthed plugs and sockets,  part 2
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flat
plugs

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Besides two more sockets, part 2 shows plugs that have a round base (∅ 36 mm ± 1.5 mm), made of porcelain, steatite or Bakelite. Part 1 shows flat plugs.

Unless stated otherwise plugs have the following features in common:
1. Pin diameter of 4 mm and pin spacing of 19 mm. Pin length is 19
mm ± 0.5 mm.
2.
Rating, if indicated, of 6 Amp - 250 Volt.

Information about German Bakelite molding marks is given at the bottom of the page.

 

Presto not earthed socket Presto socket, inside
Presto socket, contacts
 

Niko child safe socket Niko child safe socket
Niko child safe socket
Child safe adapter

1 - 3
Example of a very common type of surface mount Bakelite socket, rated at 10A-250V. Sockets had (and still have) a shallow recess; diameter varies between 37 and 39 mm. The combination of a recessed socket and round plug base gives a good protection against touching pins under tension. The type of contacts (images 2 and 3) is simple but effective and was used by several manufacturers. Contacts are accessible for plugs with 4.0 and 4.8 mm pins.
Trademark Presto was used by Gebrüder Vedder, Fabrik elektrotechnischer Apparate in Schalksmühle (Westfalen, Germany). The company, founded in 1904 is later renamed to Presto-Vedder and still exists. Dating: 1930s - 1960s.   {RH}
4 - 6
Bakelite 10A-250V socket with child-safe locking mechanism. The lock that has to be rotated to insert a plug (images 5 an 6), is an integral part of the socket construction, rather than add-on types of shutters. After releasing the plug, a spring ensures that the plate automatically rotates back to its safe position.
This 1950s socket was a significant safety improvement. Brand name: NIKO, a still existing company, established in 1918 in Sint-Nikolaas, Belgium.
7 Bakelite safety adapter with a child-safe locking mechanism comparable to NIKO socket no. 4. Adapter pins have a length of 19 mm, identical to common plug pin length. The adapter can be used on most two-pole socket, but is incompatible with Schuko sockets. No brand name.

Unknown porcelain plug Unknown steatite plug
Siemens Schuckertwerke porcelain plug
Unknown steatite plack and white plugs

Thega-Kontakt steatite plug Thega-Kontakt steatite plug
Felmas steatite plug
Felmas steatite plug

8 Porcelain plug with bottom plate made of insulating board. It was a 'classic' model that has been produced for a log period in France and other countries. Manufacturer is unknown. Dating 1900s - 1930s.   {RH}
9 Steatite plug. Fixation if wires correspond to a quite commonly used mechanism shown in more detail in image no. 18. Unknown brand; probably made in Germany in the late 1910s  to 1920s.   {RH}
10 More sophisticated steatite plug from Siemens-Schuckertwerke in Berlin (right logo). The steatite body was produced by Steatit-Magnesia, Dralowid Werk in Teltow bei Berlin (left logo), a company that was responsible for steatite parts of many plugs and sockets of various manufacturers. Dating: 1920s.   {RH}
11 Two similar steatite plugs of unknown German origin. Apart from the use of black versus white glaze only the method to fix the upper and lower part of the steatite housing is essentially different. Bolds of the black plug are exposed and resembles plug nos. 9 and 10 shown on part 1 page. The bolds of the white plug are countersunk, a more safe design. Therefore the white plug might be a more advanced and/or luxurious model.   {RH}
12, 13
Compared to Bakelite plugs (see below) it is more difficult to provide porcelain plugs with an effective cord grip. However methods to prevent that cords are fixed only at the pin contacts have been developed. The  plug made by Thega-Kontakt in Berlin has holes on both sides, close to the cord exit. Image no. 13* shows how a thread through these holes can be used for cord fixation.    {RH}
* Image no. 13 is an edited version of a picture found on bay. Plug nos. 12 and 13 are not identical.
14, 15 Felmas* plugs has developed a cord fixation method comparable to images 12-13. Holes for the thread are positioned in the basal part of the plug. Image no. 15 is a top view of the Felmas plug. Holes at 3 and 9 o'clock are used by electrical wires; holes at 12 an 6 o'clock are meant for the tread to fix the cord. Plug nos. 12 and 14 probably date back to the 1920s.   {RH}

*Felmas = trademark of Gustav Schortmann & Sohn Fabrik Elektrotechnischer Spezial-artikel in Leipzig. In the 1930s it was one of German market leaders for plugs and appliance connectors, but after WW II the company hardly survived Soviet Union reparations. There have been made Felmas installation materials, but the successful prewar years were definitely over.

Siemens-Schuckert plug type NSt 6/2 k
Steatite plug made by Voigt & Haeffner
Spelsberg-Koring plug

Weisse & Co-plug
Weisse & Co-plug, detail
Bakelite plug No. 3003 made by Felmas

16 Siemens-Schuckert plug type NSt 6/2 k, made from about 1910 until 1930. Plug consists of a single block of an early synthetic pressed material, reinforced with asbestos fibers. Screws to attach wires to pins are accessible from outside but cannot be touched when the plug has been put in a recessed socket. These strongly build plugs were probably mostly used for commercial equipment, rather than domestic appliances.   {RH}
17 Steatite plug made by Voigt & Haeffner in Frankfurt. Dating: 1920s. The plug is remarkable because of its pin design. Pins have inside a long, bended spring. The spring prevent that split pins remain pressed together after having been inserted in a relative narrow contact of a socket or connector. Squeezed pins were a common feature of plugs with split pins.   {RH}

note
 
Image nos. 18 to 33 show Bakelite plugs that are made between late 1920s and mid 1960s, but used even longer. The museum collection has dozens of examples made by a large number of manufacturers. Most plugs are German made. Others are made in France (Legrand, l'Ébénoid), Belgium (Vynckier), Italy (A.A. & G Stucchi) and the Netherlands (Corodex, HAF). Find below a small selection of plugs that illustrates the diversity in shape and design. Attention is given to wire fixation and cord grips.
 
18 Basic model with a relative small cast, without base plate. Made by Spelsberg & Koring in Altroggenrahmede (Westfalen, Germany). Wire fixation: comparable to image no. 20; no cord grip. Probably early 1930s.   {WN}
Although the plug has no cord grip, there is still a possibility to secure a cord according to a method shown on a separate page.
19, 20 Basic model with protective base plate. Pins have a screw thread to fix pins in the Bakelite cast. The thread is also uses by a circular nut for wire fixation, a method that was also frequently used on porcelain and steatite plugs (see nos. 9 and 14). No cord grip. The example has been made by Weisse & Co., Fabrik elektrotechnischer Artikel in Gräfenthal (Thüringen). The production of such plugs started in the 1930s and may have lasted until the late 1940s.
21 Bakelite plug made by Felmas. Gustav Schortmann introduced in 1935 a method to fix the cord. It was (and probably still is) an unsafe habit to remove a plug by using the cord as a towline, which means that the contact between wires and pins have to withstand considerable towing forces. Felmas plug type 3003 has a large bold (green arrow) to fix the cord. In a Felmas leaflet it is claimed that the construction is "bombenfest" (i.e. extremely robust).   {RH}

ABL Bakelite plug
Siemens-Protos Bakelite plug
Nostitz & Koch Bakelite plug

ABL Bakelite plug
Kostal Bakelite plug
Erich Jaeger Bakelite plug

22 Plug made by Bayerische Elektrozubehör, founded by Albert Büttner in Lauf bei Nürnberg (hence ABL) in the 1930s. The plug shows a rather unique approach to facilitate wiring by simply detaching the Bakelite pin holder. The plug doesn't have an effective cord grip.   {WN}
Note that
'Graetzor' porcelain appliance connector no. 5 has a similar detachable pin holder. It might be that an ABL patent has been used for the connector.
23 After unscrewing the base plate it is easy to wire this plug. It is one of the designs in the Protos series of Siemens-Schuckertwerke in Berlin. No cord grip. Dating: 1930s   {WN}
24 Plug with cord side entry, made by Nostitz & Koch, Fabrik elektrotechnischer Apparate in Chemnitz (Sachsen). The cord side entry has a height of only 3.5 mm. A cord with a diameter of ca. 4 mm will be squeezed tightly between basal part and plug cap. Thinner cords have no grip and the use of thicker cords will result in a not fully closed plug. Dating: 1940s.   {WN}
25 ABL plug with a strong, metal cord grip. A 1937 ABL catalog mentions the plug made of brown Bakelite to which textile was added. This luxury model was more expensive than the standard, black Bakelite model (90 versus 60 Mark per 100 plugs).    {FSE}
26 Plug made by Leopold Kostal in Lüdenscheid (Westfalen), characterized by an unusual type of pin fixation. Dating: 1950s-'60s.    {WN}
27 The most 'modern' type in the series of Bakelite plugs. In contrast to each of the previous models this plug has solid pins with a diameter of 4.8 mm, rather than 4.0 mm partly split pins. Because of thicker pins, it is rated at 10A-250V and can be regarded as a direct precursor of CEE 7/2 plugs. The plug has been made by Erich Jaeger in Bad Homburg vor der Höhe (north of Frankfurt) in the 1960s.   {WN}

Vynckier Bakelite plug
Wolff & Co. Bakelite plug

Stotz-Kontakt Bakelite plug
Corodex Bakelite plug

28 1930s plug made in Belgium by Vynckier Frères & Co. in Gent. It has an less usual type of cord grip. The basal part has a large Bakelite cone that presses the wires to the circular wall of the cord exit. The amount of pressure is controlled by the force that is applied to assemble both parts of the plug, A method that works good for separate wires with a diameter of 2.0 - 2.5 mm.   {WN}
29 Plug and matching connector made by Wolff & Co. in Walsrode (north of Hanover). Cords can be fixed with large screw at the sides (green arrows). The plug cord is protected by a flexible, 4 cm hollow spring, a feature commonly found on appliance connectors, but rare on ordinary plugs. Dating: second half of 1930s.   {WN}
30 Large (cast length: 83 mm), watertight plug. The porcelain cord grip is flanked by a rubber seal and flat washer. Brand name: Stotz-Kontakt, Fabrik elektrotechnischer Spezialartikel, Mannhein (from 1939 Heidelberg; now part of ABB Busch Jaeger). The Bakelite cast has code 32-S, which means that it has been made by Preßstoffwerke H. Römmler in Spremberg (Sachsen).     {WN}
31 Plug and connector made by Corodex, a Dutch company that was specialized in making Bakelite casts. Nowadays the company uses modern thermosetting plastics, but ceased plug production. The shown models dates back to the late 1950s - early '60s.    {WN}

AEG Bakelite and rubber plug
Rademacher Bakelite plug
Wooden plug
Merten cord intermedriate outlet

Bakelite plug made EP



32 Bakelite plug and cord molded in a protective rubber housing made by AEG (Allgemeine Elektricitäts-Gesellschaft in Berlin). The technique of making fully watertight appliance cords was an important improvement for equipment that was used under wet conditions. Both Siemens and AEG offered sealed appliance cords under the name Flexo. AEG has sold them at least up to the early 1950s.   {RH}
33 Bakelite plug with two protective rubber bands (green arrows). The plug has solid 4.0 mm pins; in the 1930s an uncommon feature. Brand name: Ernst Rademacher, Fabrik technischer Leuchten (lighting products) in Düsseldorf.    {WN}
34 Wooden plug. Most wooden plugs were made in the early days of home electrification. However, the shape of the plug indicated that it has been made in the mid 1940s, a period when there was a severe shortage of nearly everything.   {RH}
35 Bakelite outlet designed to be used at a position somewhere between plug and connector of a flex cord. Brand name: Gebrüder Merten in Gümmersbach (east of Cologne). The MPAD mark has a Bakelite code S. Letter codes have been used from the mid 1920s to - probably - mid 1950s. The specimen shown is probably made in the 1950s.   {WN}
36 Basic plug model, commonly used in the 1950s and '60s. The zigzag course that the wires have to follow takes tractive forces away from the pin screws. It is yet unknown which manufacturer used a logo with an E and P. It is probably not a German plug because this and other EP plugs do not have molding marks (see below), neither German VDE certification marks.   {PO}.

 

Molding marks  (Pressmassen Prägemarken)

The German Technical Association of Manufacturers of Standardized Molded and Compression Molded Materials introduced in 1924 an industry standard for Bakelite and comparable resins. Molding marks were issued by MPAD,
the Staatliche Materialprüfungsamt zu Berlin-Dahlem
(State Materials Testing Institute in Berlin-Dahlem). Testing
of Bakelite products by MPAD ended early 1960s.

In general, testing was not compulsary, but in the 1930s-'50s it was mandatory for products that could be delivered to German Rail, Post and Army.

Links to lists with MPAD codes: 1938 list, 1954 list, and a not dated list with some more codes.
 
Information about molding marks, dating of plugs and logos of electro-technical companies have been given Reiner Hahn.

Bakelite Molding Mark 33-S Bakelite Molding Mark F2-S Bakelite Molding Mark 8X-31 Bakelite Molding Mark MU-51

Examples of MPAD marks with
codes that identify the press work* (top) and the pressed material (bottom).
33 = Wolff & Co. (Walsrode). F2 = Frans Stauch (Unterrodach):
8X = Martin Kaiser (Hochstadt am Main); MU = Maeler & Kaege (Ingelheim am Rhein).
S, Typ 1 and 31 = phenolic resin (Bakelite) reinforced with sawdust filler;
  131 = urea-formaldehyde resin with cellulose;  51 = phenolic or cresolic resin with cellulose.
More codes existed for other resins and/or filling agents.

* Most manufacturers had their own press work facility, but production of casts could have been contracted out. In such cases the MPAD code corresponds to the company that made the casts (see no 30).

 


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