Requirements of a Good Lighting Scheme

Power SystemsUtilisation of Electrical PowerUtilization of Electrical EnergyElectrical Engineering

Good Lighting Scheme

A good lighting scheme is the one under the influence of which the eyes of a person do not feel any strain. For example, if the light is too dim, then we cannot observe the objects properly or cannot do reading or writing work. On the other hand, if the light is too bright, then our eyes start watering and are made to open forcibly. However, the good lighting does not have the above mentioned effects, but we find comfort while working under it.

Requirements of Good Lighting Scheme

In order to make a lighting scheme good, the following factors are to be considered while planning the lighting scheme −

  • Illumination Level

  • Absence of Glare

  • Uniformity of Illumination

  • Contrast

  • Color Rendering

  • Shadows

Let's check the importance of each of these factors in detail.

Illumination Level

The visibility of the objects depends upon the level of illumination, i.e., the magnitude of light falling over them and the light reflected by the objects. The illumination level in turn depends upon the following factors −

  • Size of the object – If the object is smaller in size, then greater is the level of illumination required for its proper visibility and vice-versa.

  • Distance between the light source and the object – If the distance between the light source and the object, then level of illumination required will be higher.

  • Distance between the observer and the object – Smaller distance between the observer and the object requires lower level of illumination and vice-versa.

  • Color of object – For the dark colored objects, the level of illumination required will be higher.

  • State of object – Stationary objects require lower level of illumination as compared to the moving objects.

  • Period of observation – Objects to be observed continuously for longer period require a higher degree of illumination.

Absence of Glare

Glare is the sensation experienced by human eyes when some light rays enter the eyes directly from a source of light. For example, car drivers use dipper at night when facing other vehicles to avoid the glare. Therefore, a good lighting scheme must not have glare.

In case of lighting scheme, the glare is of two types viz. −

  • Direct glare – If the level of mounting the lamps is too low and no reflectors are used, then the effect will cause direct glare.

  • Indirect glare – The indirect glare is caused by a shining object reflecting a major portion of incident light. The indirect glare can be avoided by fixing the lamps at such a position that no direct light falls on a shining surface.

Uniformity of Illumination

The human eyes have to adjust its aperture depending upon level of illumination within the field of vision. If there is lack of uniformity in the illumination, then the iris of eye has to adjust more frequently and causes fatigue to the eye. Therefore, it is also a requirement of a good lighting that it should have uniformity of illumination.

Contrast

The abrupt contrast in the lighting scheme should be avoided. When we go from sunlight into a dark room, we require sufficient time to locate the things properly inside the room. This is due to abrupt change in the contrast of the illuminated surface. For this reason, a lighting scheme is said to be good only if it has no contrast because it causes strain on the eyes.

Color Rendering

The color of the incident light affects the appearance of color of the object. Therefore, in a good lighting scheme, the composition of the light should be such that the color of the object appears natural and makes no difference from that under light.

Shadows

The shadows play a vital role in the design of a lighting scheme. In case of industrial lighting, the deep and dark shadows can be source of an accident. On the other hand, the dull shadows are a necessity to give a three dimensional look to any solid object. Another case is that of a place entirely free from shadow which can be a drawing office of an architect or a planning engineer.

Therefore, long and hard shadows should be eliminated as they cause fatigue on eyes. However, the complete absence of shadow is also not a good lighting, i.e., dull shadows are required to give the three dimensional view of any object.

raja
Updated on 05-Apr-2022 10:48:14

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