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EC111A Rapid Nigrescence Lighthouse Lamp |
Earlier British lamps had low voltages of 50-100V, because they were operated from batteries or diesel generators in remote places beyond the reach of the electricity grid. The higher power lamps had one or two filaments, and their light output was coded with massive rotating optical systems. By the 1960s mains supplies began to reach the larger lighthouses and a 240V lamp became feasible - and efforts were made to enable pulse the light signal electrically.
The first lamp for this purpose was the 240V 3000W EC111 developed by Osram-GEC, which employed six small 500W filaments in a triple cylindrical configuration so as to reduce the nigrescence time of the cooling filaments, and achieve better defined light pulses. That was produced until 1975/76 when it was replaced by this superior EC111A of Thorn Lighting. It employs a considerably simpler arrangement of four 750W filaments arranged in a box configuration
The lamp is hand-made throughout, its stem having a lateral Jaeger exhaust tube. The filaments are mounted on heavy nickel rods clamped to the stem with nuts and bolts. The bulb is mouth-blown in Monax glass by Moncrieff glassworks of Scotland, and the cap hand-turned from solid copper by Lamp Caps of Chesterfield. A last run of EC111A lamps was produced by Thorn at Buckie shortly before its closure, and they became obsolete around 1996 following the conversion of the last lighthouses to 1000W MBI metal halide lamps.
| Manufacturer: | Thorn E.M.I. | Type EC111A |
| Lamp Power: | 3000 Watts | |
| Lamp Voltage: | 240 Volts | |
| Lamp Current: | 12.5 Amperes | |
| Cap Type: | P89s/82x75 | Solid Copper & Porcelain |
| Bulb Type: | GS-200 | GS-63 in eighths/inch |
| Bulb Finish: | Clear | Monax borosilicate glass |
| Filament Type: | 4C-13X | Box |
| Filament Size: | 27mm x 62mm | |
| Atmosphere: | Argon-Nitrogen | Red phosphorus getter |
| Luminous Flux: | 52,500 Lumens | |
| Luminous Efficacy: | 17.5 Lumens per Watt | |
| Luminance: | ||
| Colour Temperature & CRI: | CCT: 2900 Kelvin | CRI: Ra 100 |
| Chromaticity Co-ordinates: | CCx: 0.444 | CCy: 0.406 |
| Rated Lifetime: | 800 hours | |
| Burning Position: | Vertical cap down ± 30° | |
| Overall Length: | 405±10 mm | 16 inches |
| Light Centre Length: | 235±3 mm | 91/4 inches |
| Factory: | Buckie | Scotland |
| Date of Manufacture: | Approx. 1986 | Serial No: 12-12 |
| Original Value: | GB£59.33 (1977) | |
