GEC MBI/H 2000W White

Osram-GEC was relatively late to enter the market for general lighting metal halide lamps and never became particularly successful. Its products were not especially efficient, or stable in colour during life, and the life was rather short by comparison with its competitors.

The arc tube is constructionally similar to the company's mercury products. It is fabricated from 3 pieces of quartz, the narrowed end sections serving to reduce the size of the pinch-seal and avoid a cold spot behind the electrodes. It is dosed with the halides of sodium (peach colour), thallium (green) and indium (blue).  By adding these constituents in the appropriate quantities it is possible to balance their respective radiations to yield a white light output.

The arc tube is supported on an electrified frame, which is sleeved in quartz to reduce sodium loss by the photoelectric effect. The frame has a most unusual asymmetric design, the intention being to position this uppermost and use the magnetic field to straighten the arc. Efforts have been made to limit electrolysis around the pinch-seals by supporting the arc tube between pairs of electrically insulating ceramic blocks. The outer jacket consists of a tubular borosilicate bulb without any hydrogen getter - that was added to GEC lamps only in the late 1980s. A pair of mica discs in the neck serve to limit the cap temperature. The cap is unusual for such a high wattage lamp in that it is not of the usual skirted variety - the large outer bulb has been necked inwards so as to allow use of a standard E40 cap. Owing to the weakness of this construction, the far end of the bulb features an inward-pointing dimple to provide additional mechanical support.
Manufacturer: The General Electric Company of England PLC
Lamp Power: 2000 Watts
Lamp Current: 9.1 Amps
Lamp Voltage: 240 Volts
Cap Type: E40s/45 Nickel plated Brass + vitrite
Bulb Type: TT-100 TT-31.5 in eighths/inch
Bulb Finish: Clear Borosilicate glass
Electrodes: Backwound Tungsten
Arc Length:
Atmosphere: Inner: Hg, NaI, InI3, TlI3 | Ar Outer: Nitrogen
Luminous Flux: 180,000 lm (@ 100 hrs) 160,000 lm (@ 1000 hrs)
Luminous Efficacy: 90.0 lm/W (@ 100 hrs) 80.0 lm/W (@ 100 hrs)
Colour Temperature & CRI: CCT: 3200K CRI: Ra 65
Chromaticity Co-ordinates: CCx: 0.421 CCy: 0.392
Rated Lifetime: 2,000 hours 80% survival, 80% flux
Warm-up & Re-strike Time: 2 minute to 80% flux 10-15 minutes
Burning Position: Horizontal ± 20°
Overall Length: 426 mm 16 3/4 inches
Light Centre Length: 258 mm 10 1/8 inches
Factory: Shaw, Oldham England
Date of Manufacture: August 1984
Original / Present Value: GB £181.46 (1988) GB £434.60 (2015)
References: 1) Osram-GEC Lamp Catalogue, UK, 1985/86, p.212
2) Osram-GEC Price List 1988