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overview of types of plugs and sockets
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In the early years of electrification the nowadays Czech Republic and Slovakia were a part of the Austro-Hungarian Empire. From November 1918 until the end of 1992 the countries were united as Czechoslovakia.
In the 1920s and '30 the country belonged to the top five industrialized states in Europe. Industry was concentrated in Bohemia and Moravia, regions that now constitute the Czech Republic.

Current models of Czech plugs and sockets - that are also used in Slovakia - are shown in image nos 1 - 17. Classic material is shown in images 18 - 23.

The museum is indebted to Tomáš Drahoňovský and  ABB Elektro Praga in Jablonec nad Nisou for donating items 1 - 14. A short history of the company is given below.


ABB Elektro Praga series Levit socket
ABB Elektro Praga series Tango dual socket
ABB Elektro Praga series Element dual socket
ABB Elektro Praga

ABB Elektro Praga IP54 socket with lid
ABB Elektro Praga 16A socket
ABB Elektro Praga CEE 7/7 plug

Intro Already in 1933 the Czechoslovakian Electrotechnical Association (ESČ) stipulated that from June 1934 earthed sockets must be installed in all new buildings, homes included. Czechoslovakia was probably the first country in which this safety rule was made mandatory for all new wiring installations. Poland followed soon.
Initially Czechoslovakia opted for the Schuko system, but finally decided to chose for sockets that have an earth pin (now known as CEE 7/5 standard). Read more about the origin of earth pin sockets on a separate page.

CEE 7/5 standard domestic socket, rated at 16A - 250V. Sockets must have a recess (depth: 14.7 mm). Earth pin diameter: 4.8 mm. Socket earth pin makes contact first when a plug is inserted.
Modern Czech sockets have safety shutters, operated by simultaneous entry of line and neutral pin.

Shown is an example of the ABB Elektro-Praga Levit® line.
2, 3
Dual socket with a 32ş rotated top outlet. Image no. 3* illustrates the benefit of a rotated outlet when using plugs with cord side entry.
* image of the Element® line dual socket has been copied from Czech tzb-info site.
Socket with lid, rated at 16A - 250V. The socket has International Protection rating IP 44* which mean that it can be used among others in bathrooms.
* first digit: protection against ingress of solid objects with a diameter larger than 1 mm; second digit: protected against splash water from any direction.
5 CEE 7/6 plug, rated at 16A - 250V. Pin diameter: 4.8 mm.
Elektro-Praga designed in the 1950s a plug to bridge the gap between earthed sockets used in Czechoslovakia (see no. 1) on the one hand and the German Democratic Republic (using Schuko) on the other. This so called joined plug complied with Czechoslovak ČSN ESČ 107 standard. It became a successful export product.
The image shows an essentially identical, but more recent model, that is now better known as a CEE 7/7 hybrid plug. Rating: 16A - 250V. It will be clear that also not earthed 2.5A CEE 7/16 (Europlug) and 16A CEE 7/17 plugs fit in standard Czech sockets.

ABB Elektro Praga 10-16A plug

ABB Elektro Praga plug 5536.
Rating: 10-16A - 250V;
pin diameter: 4.8 mm;
cord side entry.

Czech CEE 7/6 plug no. 5536

7 - 8
Plug 5536 consists of three parts: (8a) thermo-plastic cast, (b) black body with pins and earth contact, and (c) top cover.
Fig. 8d shows the assembled plug (identical to image no. 7).
Cast 'a' has four holes that allow mounting pin body 'b' in four, 90 degrees rotated positions. Images 'd', 'e', 'f' and 'g' show the resulting plugs. To emphasize the different pin and earth contact orientations each plugs is shown with cord entry down.
This clever design is the best selling general purpose plug in Slovakia. Information provided by Lubomir Tomik (Nitra, SK).


CSN 35 4517 type C socket and plug
CSN 35 4517 type C pin configuration

Type C

220 V DC

1-pole +E
CSN 35 4517 type C1 socket and plug
CSN 35 4517 type C1 pin configuration

Type C1

110V AC

1-pole +E

CSN 35 4517 type C2 socket and plug
CSN 35 4517 type C2 pin configuration

Type C2

110 V DC

1-pole +E

CSN 354517 type D socket and plug
CSN 35 4517 type D pin configuration

Type D

400 V AC

+N, +E

CSN 35 4517 type K socket and plug
CSN 35 4517 type K pin configuration

Type K

48 V

O = pin
without wire

CSN 35 4517 type L socket and plug
CSN 35 4517 type N pin configuration

Type L

48 V AC


9 - 14 Czechoslovakia had, and both the Czech Republic and Slovakia still have, a variety of uncommon flat pin* plugs and sockets for special purposes. The six types shown below probably date back to the 1930s.
The original Czechoslovak standard ČSN ESČ 153 has been replaced by the Czech standard ČSN 35 4517.
* flat pin size: 5.0 x 2.5 mm, 18.5 mm long. Diameter of round pin (type K): 6.0 mm.
Each of the six types is rated at 10A - 250V (C, C1, C2) / 440V (D) / 48V (K, L). Specifications of intended AC or DC voltage are given in the images below. Low voltage type K is still used in specific industrial environments where 230 Volt is not allowed for safety reasons. The 48V 3-phase type L is occasionally used in energy storage devices.

Comparison of pin postitions of CSN 354517 type C and HNA plugs

ČSN 35 4517 lookalike material once made by other companies.

HNA (Handelsschiff-Normen-Ausschuss), a German shipbuilding standard that dates back to 1917 is similar to type C. However, because of small differences between type C and HNA - see figure left -  the two types are incompatible; even applying brute force doesn't help.

Stotz-Kontakt model 14219 (see 1939 catalog) is fully identical to type C1.
The German company (now part of ABB Busch-Jaeger) has ended production of the model.

A 4-pin model made by the Austrian company ELIN has a pin configuration that looks similar to type D; see scheme i in a 1936 catalog.


Czech 6A appliance couplers

Czech 2.5A appliance couplers (1)
Czech 2.5A appliance couplers (2)

Image nos 15 - 17 show classic appliance couplers. Shown inlets, outlet and plugs, made by Elektro Praga, are still on offer for repair of older, still functional equipment and appliance cords. The Elektro Praga article numbers are given for each appliance coupler. Inlets, outlet and plugs are depicted to scale. The museum is grateful to Matúš Goĺa for donating the material.

15 6A - 250 V appliance inlet (5913) and connector plug (5816). Plugs have earth contact strips on opposite sides; see plug side view. Plugs are not polarized. The models are identical to couplers made by the German company Kautt & Bux; see nos 24 and 25 classic connector page 2.   {MG}
Flat blade size: 2.0 x 5.0 mm, length: 15.2 mm;  blade spacing (center to center): ca. 10.5 mm
16, 17
2.5A - 250V appliance inlet (5911), matching connector plug (5813), variant model plug (5823), appliance outlet (5211) and matching male connector plug. The variant model 5823 fits in an intlet with a vertical and  a horizontal blade (not in the collection). Also a 'tandem' variant with two horizontal blades have existed. Both standard and variant plugs are polarized because they have a single earth clip and power contacts are positioned off center. The 2.5A appliance couplers were a unique Czech design, according to Czech norm ČSN 354508. The norm was cancelled and production ended in 1995.   {MG}
Flat blades size: 1.4 x 2.5 mm, length: 12.3 mm;  blade spacing: 6.0 mm


Classic material

The museum is grateful to Stanislav Kotula for providing information from Elektro-Praga catalogs and scanning Kramer und Löbl 1938 10 Amp appliance connector (image no. 22, left)


Czechoslovak, 6A not earthed plug Czechoslovak 16A earthed plug Czechoslovak 3-way multi-plug, not earthed Czechoslovak 3-way multi-plug, earthed
Czech appliance connector plug made by Buellmann
Czechoslovak, 10A earthed appliance connector

18 Bakelite, not earthed plug, rated at 6A-250V. Pin diameter: 4.0 mm. The type of plug does not fit in sockets installed from 1934. Therefore it must have been made for replacement in pre-1934 wiring installations, or it was meant for export.
Plug has 1372 and the triangular Elektro-Praga logo introduced in 1946. An identical plug, with same number 1372 is mentioned in the 1938 Kramer und Löbl* catalog. In the Elektro-Praga 1950 catalog the plug has 5402-10. These facts indicate that the shown plug dates to the late 1940s.
* pre-WWII electro-technical company that became Elektro-Praga in 1946 (see short history, below).
Earthed, 6A-250V plug suitable for sockets with earth pin. The Czechoslovak standard ČSN ESČ 107 (similar to CEE 7/5-6) became compulsory in 1934. Pin diameter: 4.0 mm; earth contact accepts 4.8 mm pins.
Shown plug is listed in Elektro-Praga 1963 catalog. (no. 5420-10).   {RH}
20 Not earthed 3-way multi-plug rated at 6A-250V. Contacts can accommodate plugs with 4.0 mm pins only. Plug is mentioned in 1938 Kramer und Löbl catalog, but shown model has an Elektro-Praga logo and must have been made (shortly?) after WWII.
21 Earthed 3-way multi-plug, rated at 10A-250V. Both power pins and earth pins have a diameter of 4.8 mm. Elektro-Praga model no. 5320-20, introduced in 1950.   {RH}
Appliance connector plugs, rating 10A - 250V. Left: image copied from Kramer und Löbl 1938 catalog. Right: plug with same Bakelite housing, but flexible cord guide and earth connection are missing. Left plug has the common KL logo, whereas the other plug has a similar logo with capitals H and B. Research has revealed that HB are the initials of Hans Büllmann.
German army invaded Czechoslovakia in 1939. The Jewish Hugo Löbl was dismissed and during WWII replaced by Hans Büllmann. Initials KL in the company logo changed into HB. Production shifted to war industry. A cut down on not strictly necessary materials including plug cord guides, earth clips etc. could have been a possible consequence.
23 Earthed appliance connector, rated at 10A-250V. Complies with German standard DIN VDE 49491. Connector has a Czechoslovakian ESČ certification mark that is also shown on plug no. 19 and multi-plug no. 21. Manufacturer: Elektro-Praga, 1052. Dating: introduced and patented in 1947.   {RH}


Logos of Kramer & Loebl, Elektro Praga and ABB

a. Logo used by Kramer and Löbl on electrical accessories (until 1940).

b. Logo introduced in 1946 for the group of manufacturers of electro-technical appliances.

c. Logo on plugs, sockets, switches etc., made in Jablonec nad Nisou from 1960.
Found on nos. 6, 15, 16, 19,  21 and 23.

d. Asea Brown Boveri logo on products made from 1993.
Found on nos. 1, 2, 4, 5 and 9 - 14.

Plug no. 7 has both logo 'c' and 'd'.

Plugs made by Kramer and Löbl in the 1930s are missing in the museum collection.
Suggestions were to find them are welcome.

Short history of ABB Elektro Praga

Gustav Kramer and Adalbert Löbl started production of refined glass and crystal lamps and chandeliers in Jablonec nad Nisou (Gablonz in Austro-Hungarian Empire).

With the growth of electrification Kramer and Löbl started production of accessories related to electric lighting, as sockets, plugs and switches. It proved to be a profitable market. Glass production was scaled down and ended in 1924. The company was renamed 'Kramer und Löbl, Fabrik elektrotechnischer Artikel'. Adalbert Löbl's son Hugo joined the company. He promoted strongly the move toward electro-technical material.

Kramer and Löbl introduced the Bakelite molding process in Czechoslovakia. The company became the dominant manufacturer of electrical accessories and exported products to many countries all over the world.

annexation of Czechoslovakia by Nazi Germany, the company was confiscated. The Jewish owner, Hugo Löbl, was dismissed and replaced by Hans Büllmann. From 1940 production was fully focused on war industry.

After World War II, industry was nationalized in Czechoslovakia. Electro-technical companies were merged and renamed to Elektro-Praga. The plant in Jablonec nad Nisou had the monopoly for manufacturing electrical accessories. Production grew steadily and from the 1960s export started to other countries.

State owned enterprises were privatized. In 1993 Elektro-Praga in Jablonec nad Nisou became part of the Asea Brown Boveri (ABB) concern.

Sources: English  /  Czech (illustrated)


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