Museum of Plugs and Sockets logo, small Appliance Connectors
Classic models, part 2
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Part 2 of the collection of classic appliance connectors is devoted to Bakelite plugs made in Germany. Bakelite plug production started in the early 1920s and was used for almost half a century. It was gradually replaced by other plastics in the 1960s.
Many items on this page have been donated by Reiner Hahn {RH} and Wieger Nieuwenhout {WN}. Information about molding marks has been given by Reiner Hahn.


Bakelite

Bakelite was developed by Leo Baekeland in 1907 and patented in 1909. It is a phenol formaldehyde resin that can molded to produce large quantities of identical units. Although customized molds and molding presses were expensive, Bakelite became the preferred material for plugs as sales of electrical appliances increased dramatically from the early 1920s. Bakelite is an excellent insulator and is resistant to heat, but it may swell under prolonged humid conditions. Phenolic resins have to be reinforced with a filling agent. Sawdust was most commonly used in plugs.

Molding marks

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).

Molding marks have codes that identifies the press work and the pressed material. Images 4 and 8 shows examples.

The former German Democratic Republic (DDR) used comparable DAMW marks (Deutsche Amt für Material- und Warenprüfung).
Details are given at the page on the MPAD and DAMW marks.

 

Unknown, early Bakelite appliance connector
Inside view of unknown and Kostal appliance connector
Kostal appliance connector
MPAD molding mark of Kostal appliance connector

Krania appliance connector
Interior of Krania and von der Horst appliance connector
Von der Horst appliance connector
DAMW and MPAD molding marks


Unless stated otherwise, for each of the appliance connectors shown on this page applies:
(i) rating of 10A - 250V, and (ii) contacts are designed for 6 mm pins, with a spacing of 19 mm.
Connector nos. 1, 3, 5, 7, 9-11, 13-22 and 28 comply with the old DIN VDE 4990 (see part 1 page) or newer DIN 49491 standard.

1, 2
Early Bakelite connector, made around 1925 or earlier. Note the solid Bakelite cast. Later Bakelite casts were hollow (see image nos 3, 5 and 7). The outside has been painted dark brown to give it a more decent look. Other connectors with a solid Bakelite cast are nos. 13 and 19/20. Connector no. 1 has no company name or logo and no VDE or MPAD mark, but it must have been made in Germany given the abbreviation D.R.P. (Deutsches Reichspatent = German state patent).   {RH}
2, 3
1950s connector, made by Leopold Kostal in Lüdenscheid (Westfalen). The concept is essentially identical to no. 1, but through the years connectors have grown in length. A hollow cast saves material and together with a hole in the center of the connector helps to cool down the plug, an essential feature if the connector was used to power an iron, kettle or toaster.   {RH}
4
MPAD molding mark of connector no. 3. The number above the M indicates the press work. The testing institute has given no. 72 to Ludwig Kostal. The other number refers to the pressing material. 31 = phenolic resin, reinforced with sawdust filler (Bakelite). This material was also indicated as Type 1 or S.
Note that MPAD testing and certification was not mandatory, which may explain why connector no. 1 has no molding mark.
5, 6
1960s or '70s connector with trademark Krania, made by VEB Elektroinstallation Kranichfeld in Kranichfeld, Thüringen (former DDR). Connectors 5 and 7 are examples of models that have porcelain tips, giving a better protection to heat. Although Bakelite is reasonably heat resistant, fully Bakelite connectors used in irons suffered from degradation and were more liable to break.
6, 7
1970s connector with earth clips, made by von der Horst (VDH) in Lüdenscheid (Sauerland). Earth clips make contact with a metal case around the the appliance inlet pins, see inset.   {WN}
8 Top: DAMW molding mark of connector no. 5. N25 = VEB Elektroinstallation Kranichfeld.
Bottom: MPAD molding mark of connector no. 3. H7 = von der Horst, Lüdenscheid
Both marks: 31 =
phenolic resin, reinforced with sawdust filler (Bakelite).

Busch-Jaeger appliance connector Felmas appliance connector 2820
Felmas plug 2820

Unknown Bakelite appliance connector
Hirschmann appliance connector ABL appliance connnector
Dr. Deisting  appliance connnector

9 Connector probably made by the Lüdenscheider Metallwerk AG, Busch-Jaeger. The connector doesn't have any marks, but the wall plug that have the same look, has Bush-Jaeger marks. The textile structure was a feature of a luxury series.   {RH}
10 Felmas connector no. 2820. The trademark Felmas* was used by Gustav Schortmann & Sohn in Leipzig. Schortmann did not had his own press work. The MPAD molding mark tells that the Bakelite parts came from Bisterfeld und Stolting in Radevormwald (Rheinland). To improve heat resistance Bakelite is reinforced with asbest type 1. The connector is mentioned in a 1935 Felmas brochure. It states that plug no. 2820 - the model shown here - can resist 250 degrees.   {RH}

*Felmas = Fabrik Elektrotechnischer Spezial-artikel.
Felmas was in the 1930s one of the German market leaders for plugs and appliance connectors. After WW II Leipzig was situated in  the Soviet occupation zone. Large parts of the East German industry were claimed by the Soviet Union for reparations. Among others Schortmann's company was badly hit.
11 Not earthed appliance connector. The metal case is for protection of the fully Bakelite housing only (see right image). Dating: probably mid 1920s. The manufacturer is unknown; connector has no company logo or molding mark.   {WN}
12 Two connectors made by Richard Hirschmann, Fabrik für Radioteile in Esslingen (Neckar). Left: non-earthed type with a luxury look comparable to connector no. 9. Right: earthed type. Both models have a relative large steatite part to protect the connector against heat. Probably 1930s models.   {RH}
13 Earthed connector made by Bayerische Elektrozubehör in Lauf bei Nürnberg, a still existing company probably better known as ABL (initials of Albert Büttner founder of the company in Lauf). Their MPAD molding mark code is 67.
The connector doesn't have the typical dark brown Bakelite colour anymore, but t
he molding mark shows that the product complies with the phenol resin with sawdust (code S) criteria. Discolouring can be caused by relative low resin percentage (<40%), addition of ammonia and/or wear and tear. The connector might be a late 1920s model.   {WN}
14 Connector with earth clips made by Dr. Deisting & Co. GmbH, Spezialfabrik für elektrotechnische Installations-Apparate und Isolierstoff-Presswerk in Kierspe (Westfalen). Probably early 1930s.   {RH}

Felmas appliance connector Presto appliance connector Lohmann appliance connector Vaudeha appliance connector

ABL switched appliance connector
ABL switched appliance connector, detail
Stauch switched appliance connector
Stauch switched appliance connector, inside

15 Connector with earth clips, manufactured by Gustav Schortmann in Leipzig, using the Felmas trademark. It is shown on the same 1935 Felmas brochure as connector no. 10. Besides the shown model no. 8980 two other variants were offered: a non-earthed type, and an earthed connector with switch. The small image bottom right shows the Schuko type plug attached to the other end of the original appliance cord. It is shown in more detail on the page about uncommon Schuko plugs.   {RH}
The museum had the flex cord and plugs on loan.
16
Appliance connectors with cord side entry. It has a MPAD molding mark with code 31 (= Bakelite), but white is not a typical Bakelite colour. Molding presses were expensive and It might be that an older press has been used with a newer type of resin. Probably 1970s. Made by Gebr. Vedder, Schalksmühle (Sauerland). The company was founded in 1904, but trademark Presto was introduced much later. Company is now renamed to Presto-Vedder.   {WN}
17 Side entry connector probably made by Lohmann & Welschehold in Meinerzhagen (Westfalen).  The connector has the inscription B.G.M., but no MPAD mark. "B.G.M." stands for Bundes Gebrauchsmuster, a German patent-like intellectual property right. Possibly 1960s.   {WN}
18 Side entry connector made by in the 1960s-'70s by Gebr. von der Horst, Elektrotechnische Fabrik in Lüdenscheid. The company used both the VDH logo (see image no. 7) as well as the Vaudeha trademark.
19, 20
Not earthed connector with single pole push switch. Only the connection to the right contact (see image no. 20) can be interrupted. Connector manufacturer is ABL (Bayerische Elektrozubehör, Lauf), but Presswerk AG in Essen (MPAD code 45) was responsible for type 2 casts. Type 2 refers to an undefined thermosetting resin with organic filling material.

The springs (green arrow) of the push type on/off mechanism results in a sudden displacement of the contact strip over a relative large distance (ca. 5 mm). Quick motion is needed to minimize arc formation, a phenomenon that is more prominent with direct current than alternating current. Tumbler switches
(for example no. 22) can only be used safely with AC. Because of slower on/off movement and smaller contact displacement metal contact points will be burned by DC arc formation.   {RH}
21, 22
Not earthed connector with double pole tumbler push switch, made by Franz Stauch, Presswerk in Unterrodach (Oberfranken, Bavaria). According to the MPAD mark the connector has type 31 = Bakelite cast, but its colours suggest the use of a more modern plastic, using and older mold. Dating: 1970s-'80s.   {WN}

The green arrow points to the tip of a flexible metal blade. When the connector is switched to 'on' the blade moves upward and makes contact with the strip that is connected to the pin contact. Contact points and blade displacement are small, and  up/down movement of the flexible blade is more gradual compared to a push switch.
For reasons explained in the caption to connector no.18/19 the Stauch connector has the warning "Nur für Wechselstrom" (only for alternating current).


Neumärker travel iron Neumärker travel iron, connector Neumärker travel iron, 220V Neumärker travel iron, 150V Neumärker travel iron, 110V

23a-e Electric travel iron (200W), made in Germany by Neumärker; probably late 1950s. It can be used in countries with a 220V, 150V or 110V network.
Switching from one voltage to another is achieved by inserting the connector in a different orientation (see image nos. 23c, d and e). The iron is not earthed; the third pin of the iron (see image no. 23b) is necessary for making different contact configurations between the pins and the three slots of the steatite/Bakelite appliance connector (see inset; the fourth slot, indicated with x, is an empty hole).
The connector - no. 1112 - has been made by ABL (
Bayerische Elektrozubehör in Lauf). The wall plug has been made by Heinrich Kopp. Both have MPAD marks; connector: 67-31, and plug: W1-31.    {FS}
 
The image right has been taken from a 1937 ABL catalog (part of page 29).
It shows a plug and appliance inlet (Geräte-Steckdose) similar to the above appliance coupler, devices that have been in production for at least 20 years.
ABL catalog 1397, part of page 29

Kautt-Bux appliance inlets
Kautt-Bux appliance connector
Non-household appliance inlet with 19mm pin spacing
ABL Schuko-type appliance inlet

Adapter for Appliance connectot to CEE 7/1 Schuko 3-way adapter with appliance coupler inlet made by Broghammer

Kalthoff 344 P/Si appliance connector

24, 25
Inlets (24) and plug (25) developed in the 1960s for non-household electrical devices, for example radios and office equipment,  by Kautt & Bux, Spezialfabrik für Kollektoren und Geräteschalter in Vaihingen (Stuttgart). Rating: 6A - 250V; pin spacing: 10 mm.
These appliance connectors and machting inlets can be regarded as precursors of the woldwide accepted ICE 60320 standard for appliance couplers. It is interesting to notice the use of side clips for earth contact. A system that is derived from older appliance connectors shown on this page.
26 Appliance inlet comparable with 6 mm pins, spaced at 19 mm. Each of the plug nos. 1 to 21, shown above fit in this inlet. The manufacturer is unknown; the inlet has no logo, MPAD or certification marks.   {WN}
27 Inlet for Schuko connector plugs. Rating: 10A (DC) / 15A (AC) - 250V. Both surface mount and flush type (shown) existed. Giving its size they were probably intended for (light) industrial purposes, rather than domestic appliances. MPAD code: 67 - 131 31. Manufacturer: ABL (Bayerische Elektrozubehör, Lauf bei Nürnberg). Dating: 1950s - '60s.   {RH}
28 Adapter to convert a non-earthed appliance cord to a flex cord that can be used for CEE 7/2 or 7/16 plugs that have 4.0 mm pins. Plugs with 4.8 mm pins doesn't fit. The adapter  has been made by Willy Buschhaus, Fabrik für elektrische Erzeugnisse in Lüdenscheid, Westfalen. It has a DRPA mark (Deutsche Reich Patent angemelded = German patent applied). A Bakelite adapter with DRPA is probably a 1930s model.    {RH}
29 3-way Schuko (CEE 7/4) multi-plug with appliance coupler inlet (DIN VDE 4991). Rating: 10A-250V. Manufacturer: Gebrüder Broghammer, Uhrenbestandteile und Elektroapparate, in Schramberg (northeast of Freiburg, Germany). Dating: 1950s.   {RH}
30 A 'classic' DIN 49491 (now CEE type T155) appliance connector that is still in production. Kalthoff GmbH in Schalksmühle is probably the only company that still offers them for replacement and special purposes. The model shown is type 344/Si, rated at 16A-250V (Kalthoff products).
The housing is made of silopren, a two-component liquid silicone rubber for injection molding processes. It can withstand 200 ºC and for a short time up to 300 ºC.   {RH}

 


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