Types of lighting scheme in industry

A lighting scheme is the way luminaires are arranged to provide light for the work in an area. Industries use the following schemes:

1. General lighting

Luminaires are spread in a regular pattern over the whole area to give uniform illumination (e.g. 200–300 lux) on the working plane, independent of where machines are placed. Spacing–height ratio is kept within limits for uniformity. Used in assembly halls, warehouses and general workshops.

2. Localised (local) lighting

Extra lamps are fixed close to particular work points (on a lathe, inspection bench, drawing board) to give high illumination (500–1000+ lux) only where fine work is done. Saves energy but gives strong contrast if used alone.

3. General plus local (supplementary) lighting

Moderate general lighting for movement and safety, plus local lamps at critical tasks. This is the usual scheme in machine shops: it is economical and avoids dark surroundings and eye strain.

4. Localised general lighting

General-type luminaires are concentrated in the zones where work is done (above machine rows), with lower lighting over gangways.

5. Emergency lighting

Battery-backed or generator-fed lights that come on when the normal supply fails, lighting escape routes, exits, stairs and critical machines (minimum about 1 lux on escape routes).

Classification by light distribution

In factories, direct general lighting with high-bay LED or metal-halide luminaires plus local lighting at machines is the normal choice, with phases distributed to avoid stroboscopic effect.