Low Weight High Lights Hipak Range light fittings for high industrial buildings and public areas. Made by Thorn Lighting Ltd Thorn House, Upper St Martin's Lane. London WC2. Designed by Colin Dipper, DipAD, LSIA Contract prices on request High bay industrial light fittings are needed for sites such as aircraft hangars, steelworks and engineering factories at heights of 7m or more. Economy, safe and easy mounting and servicing, and minimal maintenance are among the chief design criteria. It is also important to keep the weight of the fitting at an amount compatible with easy handling by installation technicians. Thorn Lighting, which already had a range of high bay lights, began to develop Hipak in 1970. The work was carried out by Colin Dipper under the direction of Peter Rodd and benefited enormously from the continuous feedback of information by Thorn's own laboratories. The design brief demanded a fitting which would embrace the most stringent European standards and explore new techniques and materials which might reduce cost and weight. Hipak fittings are, in fact, up to 50 per cent lighter than earlier, similar Thorn products. The design also provides unusually easy access to the spacious wiring box, which has facilities for a variety of wiring combinations and cable types. Since a substantial proportion of Thorn's market is in countries with hot climatic conditions, particular attention was paid to the problem of operation in intense heat and humidity. Early design prototypes tended to overheat because of a one-piece control gear housing. This was largely overcome by splitting up the control units, thus reducing the working temperatures. Tests were carried out on prototypes in ambient temperatures in excess of 40°C and it was finally decided to encapsulate the electrical ballast in an aluminium extrusion, painted with a malt black anticorrosive finish which efficiently disperses internally generated heat. The encapsulation also reduced heat transference from the ballast to the terminal block and capacitor, which are housed together in a separate wiring box. This box is made in injection moulded polycarbonate which makes substantial savings in both weight and cost. The outer frame of the fitting is made in zinc plated stove-enamelled steel. There are two types of reflector available; the range can take 250W and 4007 Kolorlux mercury lamps as well as 250W and 400W Kolorson high pressure sodium lamps and 400W Kolorarc lamps which give outstanding colour rendering. Larger fittings are being developed which will take 700/1OOOW lamps. All current models use the same family of components.

Design Journal, No.304, Editorial, April 1974. pp.35-41.