GE Lucalox LU1000 S52 with Voltage Fuse

The first 1000W HPS lamp was launched by GE in 1971-72. It had an ED-25 or T-18 bulb and delivered 130,000 lm. In 1976-77 efficacy was increased to 140 lm/W, and upgraded to feature the amalgam reservoir with butterfly crimp to allow universal burning. Prior to 1979 the outer bulb was changed to this ET-25 shape, perhaps to aid manufacture.

American 1000W 'S52' lamps have an unusually high voltage and are characterised by a very long and slender arc tube. They achieve ~7.5% higher efficacy than European low voltage 1000W lamps and due to the low operating current, electrode life and lumen maintenance is better. The support frame is strengthened while reducing shadowing by using two narrow diameter steel wires, and there is a heat + light-reflective disc in the neck area. Efficacy is further enhanced by a zirconium-aluminium strip to getter hydrogen, in addition to the usual barium getter. A glazed porcelain cap is used to avoid breakdown at the higher ignition voltages.

High voltage HPS lamps like this suffer a unique problem that arcing can occur in the outer bulb if its vacuum should be compromised, or if the arc tube leaks. The power is sufficient to melt the glass stem and burn back into the cap, destroying the lamp holder. A fuse was therefore developed, consisting of a loop of iron or nickel wire around one of the stem leadwires and connected to the other. The optimum spacing is fixed by a small glass tube of low melting point. Should arcing develop, the loop will melt into a bead and fuse to the other lead wire, shorting the lamp and tripping an external fuse. The reason for the second glass tube is to restrict arcing to the loop, not the straight wire, otherwise the molten metal may fail to bridge the stem wires.
Manufacturer: General Electric Company U.S.A.
Lamp Power: 1000 Watts
Lamp Current: 4.7 Amps
Lamp Voltage: 220 Volts
Cap Type: E39s/41 Ni plated brass + porcelain
Bulb Type: ET-79 ET-25 in eighths/inch
Bulb Finish: Clear Lead borosilicate glass
Electrodes: Backwound Tungsten Ba2CaWO6 Emitter
Arc Length:
Atmosphere: Inner: Na,Hg | Xe Outer: Hard Vacuum
Luminous Flux: 140,000 lm (@ 100 hrs) 126,000 lm (@ 12,000 hrs)
Luminous Efficacy: 140.0 lm/W (@ 100 hrs)
Colour Temperature & CRI: CCT: 2100K CRI: Ra 22
Chromaticity Co-ordinates: CCx: 0.522 CCy: 0.423
Rated Lifetime: >24,000 hours to 50% survival
Warm-up & Re-strike Time: 3-4 minutes 1 minute
Burning Position: Universal
Overall Length: 383 mm 151/16 inches
Light Centre Length: 222 mm 83/4 inches
Factory: Ravenna, OH U.S.A.
Date of Manufacture: January 1980 Date Code: 1 .-
Original Value: Unknown
References: 1) US Patent 3,767,965, High Intentity Lamp containing Internal Shorting Fuse, B.R.Collins, J.Sulcs & C.I.McVey (General Electric), filed Mar. 1972
2) General Electric USA Large Lamp Catalogue, Form 9200, 1972
3) General Electric USA Large Lamp Catalogue, Form 9200, 1973
4) General Electric USA Large Lamp Catalogue, Form 9200, 1975
5) General Electric USA Large Lamp Catalogue, Form 9200, 1977
6) General Electric USA Large Lamp Catalogue, Form 9200, 1979
7) General Electric USA Large Lamp Catalogue, Form 9200, 1980