|Bulgin and Belling Lee
|For many decades British companies Bulgin
and Belling Lee
are producing series of small connectors for lower currents. There is a
choice of configurations with 3 to 8 poles. For portable
audio and lighting equipment both
cable and chassis mounting versions exist for inlets, outlets and plugs.
The collection of classic connectors shown below has been donated to the museum by David Fisher. The material was used in the 1970s for building lighting and sound controllers and theatre use. Similar versions of some types are still in production. Details are given in the captions below.
pole, chassis mount inlet rated at 5A - 250V (image no. 1) and
matching connector plug (image no. 2). The three contacts have a
equilateral position, but a key ensures correct polarity. Pin diameter
= 4.9 mm; pin length = 13.3 mm (L and N) and 13.8 (earth). Inlet and
plug have screw terminals.
This model was commonly used to feed power into portable equipment. It is to be regarded as a precursor of IEC 60320 C13/14 connectors.
- 250V chassis mount outlet (image no. 3) and corresponding
plug (image no. 4). The outlet offers the possibility to feed related
equipments, for example to connect a turntable to the audio amplifier.
Instead of a key, correct polarity is ensured by the earth pin that has
a larger diameter than L and N pins (respectively 5.6 and 4.8 mm). Pin
length = 13.5 mm (E) and 11.9 mm (L and N). The longer earth pin and
the more external position of the outlet earth contact ensures that
earth contact is made first. Outlet and plug have screw terminals.
3-pole, 5A - 250V flex mount connector, with screw tags. Pole
position is identical to nos. 1 and 3, but compared to plug no. 2 this
angled connector has an 'inverted' type of key. This means that the
connector fits in three - 60 degrees rotated - positions into inlet no.
1. Apparently connector no. 5 belongs to another series than nos. 1 and
pole, 5A - 250V flex mount connector plug, with screw tags. Later, the
six pole connectors have been replaced by eight pole models. According
to Bulgin they are now the standard connector for disco and lighting industry.
pole, 2A - 250V outlet (image no. 7) and matching connector
plug (image no. 8). They have respectively solder buckets and tags.
Note the key that is connected to the earth contact. The model is still
(2015) in production, but now rated at 3A; see Bulgin SA2402 (outlet) and
|9||1.5A - 250V 3-pole angled connector plug, with solder tags. See also caption to image no. 10.
|10||1.5A - 50V 3-pole connector plug (left) and chassis mount inlet (right). The Bulgin 2015 catalogue
shows that plugs and inlet comparable to each of the 1.5A, 3-pole
models still exist, but now they are rated at 3A - 250V; see PX0430,
PX0646 and PX0429.
pole, 1.5A - 50V connector (left) and chassis mount inlet
(right). Comparable, modern models are PX0636 (plug) and PX0635
(inlet). They are rated at 3A - 50V.
on the cord end of connector plugs shown in image nos 10 and 11.
It is presumed that the 250V inaccessibility refers to the diameter of
the cord entry (9.4 mm) and the absence of a cord grip.
||Angled connector plugs (nos. 5, 8 and 9) have inspection ports for checking earth wire connection.
|13 - 15
L1722 3-pole chassis socket (image no. 13) and line plug (image no.
14), rated at 10A - 250V. Socket contacts are recessed and have solder
or snap-on terminals. Plug pins are fully shrouded and
have screw terminals.
Image no. 15 shows the inspection port to allow instant inspection of the earth wire connection.
The L, N and E contacts are positioned in a non-equilateral triangle to ensure correct polarity.
Belling Lee 10A power entry connectors are still available (2015).
||The rear side of socket no. 13 shows a remarkable detail. There are two codes: L1722A/S and P.O.11A (green arrow). The first code is the connector type, whereby A/S refers to a fixed power connector (chassis socket), whereas the 'free' plug has code L1722/P. The second code relates to Post Office. Belling Lee L1722 connectors were frequently used to power in to portable Post Office equipment. PO is later renamed to BT = British Telecom.|
L1436 3--pole line plug (left) and chassis socket (right), rated at 3A
- 250V. Most characteristics are identical, to the 10A model. The
images of 3A and 10A model have approximately the same scale. Although
the 3A plug and socket are undoubtable Belling Lee designs, they have a
RS, rather than Belling Lee logo (see image no. 18). RS Components
Ltd mainly sells products made by other companies, but has its own RS
label too. Apparently a link between Belling Lee and RS have existed,
but Belling Lee products are no longer in the RS catalogue.
|18||Each of the Bulgin products shown here carry the name BULGIN MADE IN ENGLAND, or BULGIN ENGLAND.
The Belling Lee logo (bottom left) is shown on the 10A socket and plug. The 3A models have a RS mark (bottom right).
Additional information given by David Fisher:
" Virtually all of the Bulgin connectors were very brittle due to their construction material which was a form of black Bakelite, apart from outlet and plug nos. 3 and 4 which was a later version made of plastic*. The Bulgin line connectors would frequently break if they were dropped onto a hard surface and the rear part would usually shatter and need replacing.
The Belling Lee connectors were much more resilient to impact and would often make a better and more reliable connection especially when frequently plugged and unplugged."
* nowadays Bulgin connectors are made of a phenolic resin, comparable to material used by Belling Lee.
|D i g i t a l M u s e u m o f||P l u g s a n d S o c k e t s|