For more than twenty-five years the G.E.C. has led the way in the design and manufacture of street lighting equipment. All over Great Britain and in most countries of the world there can be found roads lighted by OSRAM lamps in G.E.C. lanterns.

The name G.E.C. on street lighting equipment is recognized throughout the world as a guarantee that the equipment has been built on sound engineering principles, that it embodies the most modem methods of manufacture and that it will, in consequence, give the maximum possible efficiency.

Broadly speaking, street lighting and exterior lighting fall into three categories; for main roads, side roads and open spaces such as civic centres, railways and dock areas. It will be found that open spaces can best be lighted by means of equipment similar to that used for main roads, though special requirements of light distribution are sometimes necessary and colour may be an important consideration.

The basic theories of street lighting have changed little since the development of the high pressure mercury lamp by the G.E.C. Research Laboratories in 1932, although there have been many improvements in both lamps and lanterns.

Present day practice, based on innumerable experiments and installations, follows certain well established principles, and it is possible, in consequence, to plan an installation to-day, with the certain knowledge that the results will come up to expectations.

The choice of light source for a particular installation is governed by local conditions but is mainly confined to tungsten filament, H.P.M.V., sodium or fluorescent lamps. Where filament lamps are used wattages of 60 to 200 are most common for side road lighting and 300 to 500 for main roads. Lamps of higher wattages generally necessitate special lanterns which are not described here.

OSRAM H.P.M.V. lamps, which provide greater efficiency, are extensively used to-day - either 80 or 125 watt for side roads and 250 and 400 watt for main roads. With this type of lamp there is a deficiency of red in the spectrum, but this is of course no drawback at the low levels of intensity needed for street lighting.

OSRAM sodium lamps, which give a light of monochronmatic yellow, provide even higher efficiency and are available in four wattages. The 45 watt lamp is standard for side roads and the 140 watt size is extensively used for main roads.

OSRAM fluorescent lamps give excellent colour rendering and have low brightness, but in order to provide sufficient light it is generally necessary to employ multi-lamp lanterns, which are inherently bulky and expensive. This restricts their use generally to special applications.

The lanterns described in this publication are classified under main road, side road and special uses. Most of them are die castings of light alloy and are, in consequence, light to handle. Maintenance is reduced to a minimum, the greater part of the glassware is smooth externally, while simple focusing arrangements are provided. In addition, and perhaps the greatest advantage of all, is the fact that the repetition method of construction ensures absolute consistency in the optical performance.

Auxiliaries for discharge gear, such as chokes and transformers, are totally enclosed and embedded in wax to make them moisture proof, unless otherwise specified.

The space available here does not permit of all the equipment being described in detail, but further information on most items is provided in separate leaflets.

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