Sealed Beam Halogen PAR64 - CP60 EXC

Following the 1938 invention of PAR lamps for automotive applications, and the general lighting PAR38 around 1940, it took many years before they were adopted in entertainment lighting. One of the first was the 30W #4515 PAR36 Pinspot. Then followed the 300W PAR56 and 500W PAR64 for indoor & architectural floodlighting, the 120V mains being boosted to match the 3200K of other studio lights. Still more power followed with PAR64 28-volt aircraft headlamps, in particular the 250W #4552 and 600W #4559, although their beams were too narrow and the low voltage proved inconvenient.

It was not until the later 1960s that the ruggedness and simplicity of PAR lamps and PAR can fixtures won them widespread success, fuelled by developments in rock music which drew entertainment lighting equipment out of fixed-venue theatres, to mobile rigs erected at concert sites. GE addressed the power shortcomings in 1964 with the launch of halogen versions, first the 250W PAR38, followed by the 1000W PAR64 with transverse capsule and coiled-coil filament, which became the workhorse of show lighting.

These could only be made up to 120V due to problems of fragility and arcing, and in high voltage countries this limited flexibility due to the need to use them in series pairs. The problem was overcome with the 1978 invention of this lamp by Roger Hume of Thorn Lighting, which made its debut to light the film 'Flash Gordon'. The inner capsule is mounted axially rather than transversally and employs a grid filament. This increased shock resistance up to 800G and achieves superior optical efficiency with a more rounded beam profile. The arcing problems were overcome with another of Hume's inventions, by dosing a trace of hydrogen gas into the lamp.
Manufacturer: Thorn Lighting Ltd.
Lamp Power: 1000 Watts  
Lamp Voltage: 240 Volts  
Lamp Current: 4.17 Amperes  
Cap Type: GX16d Extended Mogul End Prong
Bulb Type: PAR-204 PAR-64 in eighths/inch
Bulb Finish: Aluminised reflector Borosilicate glass
Filament Type: C-13 Monoplane Grid
Atmosphere: Bromophosphonitrile Krypton + Hydrogen gas
Luminous Flux: N/A  
Luminous Efficacy: N/A  
Peak Intensity: 320,000 cd  
Beam Distribution: 9°x12° to 50% peak 17°x20° to 10% peak
Colour Temperature & CRI: CCT: 3200K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.452 CCy: 0.409
Rated Lifetime: 300 hours to 50% survival
Burning Position: Universal  
Max. Overall Length: 150 mm 6 inches
Seating Plane to Cap: 80 mm 3 5/32 inches
Factory: Leicester United Kingdom
Date of Manufacture: December 1981 Date Code: 96
Original / Present Value: GB £7.96 (1988) GB £15.38 (2007)
References: 1) Thorn Lighting Comprehensive Catalogue, 1979 UK.
2) Thorn Lighting Studio Lamps Handbook, February 1978, UK.
3) New Incandescent Light Sources for Studio & Theatre, K.R.Wolfe & K.B.Robinson, Thorn Lighting Journal 25 (Summer 1982), pp.24-27.
4) Tungsten Halogen Reflector Lamps, R.A.Hume & A.J.Barrell, Proceedings of the UK National Lighting Conference 1986, pp.246-255.
5) 1000W PAR64 in 240V Launched at Photokina Köln, Electronics & Power, September 1978, p623.