Osglim Beehive Neon Lighting Lamp

Osglim Neon Discharge lamps have been manufactured in three different styles - a lighting lamp (as pictured here), a series of small indicator lamps, and also as letter lamps.

The 5-watt Lighting lamp employs a beehive shaped coil of swedish iron wire mounted above a flat disc of the same metal. Swedish iron is the preferred electrode material for these lamps on account of its low rate of sputtering and ease of outgassing by bringing it to red heat during the pumping stage. Aluminium electrodes, as employed in Geissler tubes, also have a low rate of sputtering but they are not particularly suitable for use in a lamp requiring a high purity gas filling like this. The oxide film and low melting temperature makes it a difficult material to outgas.

The half-watt Indicator lamps are in small pygmy or tubular glass bulbs and generally have electrodes formed from sheet metal, either as a split disc, or a disc with an annular ring.

Letter lamps take the same format as the Lighting lamp but instead, have large parallel electrodes stamped out in the shape of a letter or number. When arranged side by side, illuminated signs could be created for shop windows etc.

All lamps incorporate a ballast resistance inside the cap and are filled with a neon-argon penning mixture for easy ignition on the mains electricity supply. Incidentally the name "Osglim" is frequently found on pre-1950's neon lamps from the GEC. In the same way that the Osram brand was used for general lamps and the Robertson brand for carbon filament lamps, Osglim was another GEC trade name used exclusively for neon glow lamps.
Manufacturer: The General Electric Company of England PLC
Lamp Power: 5 Watts
Lamp Current: 21 Milliamps
Lamp Voltage: 230-240 Volts
Cap: B22d/30x28 Brass + Vitrite
Bulb Finish: Clear Soda lime
Bulb Type: GS-55 GS-14 (in eighths/inch)
Overall Length: 115 ± 5 mm
Light Centre Length:
Electrodes: Beehive Spiral and Plate, Swedish Iron
Atmosphere: 99% Neon, 1% Argon
Luminous Flux: Not Published
Luminous Efficacy: Not Published
Colour Temperature & CRI: CCT: CRI:
Chromaticity Co-ordinates: CCx: CCy:
Burning Position Universal
Rated Life: Not Published
Factory: Hammersmith England
Date of Manufacture: January 1945
Original / Present Value: £4s 6d (1951) £3.75 (2001)
References: 1) Osram-GEC Lamp Catalogue, UK, 1932, p.18
2) Osram-GEC Lamp Catalogue, UK, 1937, p.34