ELETRICAL SYSTEM: INDOOR ILLUMINATION

As you #steemit follow me on electrical system information, today i will show you one of the case study and show you practical application regarding it also.

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Credit

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case study 1.

An advertisement board 6m square is fixed to a wall with the bottom edge near the ground. A lamp fitting giving a luminous intensity of 5000 candelas in all directions towards the board is fixed level with the bottom of the board and at 10m distance, giving a maximum illumination at the center of the bottom edge. Calculate the illuminations:

1. At the center of the bottom edge

2. At the center of the top edge

3. At one of the top corners.

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Following the above case, lets quickly look at the practical application on this study:

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The above is a simple inverse-square-law calculations can only be applicable to point sources or where there are no reflecting surfaces like;

a. street lighting

b. pack illuminations

c. stadium lights e.t.c.

However, for indoor illuminations a lot of factors may affect the illumination of the working plane such as:

1. Reflection from the lamp-fitting, wall, ceiling e.t.c

2. Absorption of light by lighting fittings, colour of the walls.

3. Absorption due to lamp being covered by dust, fumes in case of spraying workshops, weather conditions e.t.c.

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For all these factors allowances has to be given for an increase in the candelas output of the point source in order to overcome the losses.

Let me quickly show little steps on design of lighting for indoor illumination

a.) decide upon the illumination required, in lux, for the working plane

b.) calculate the room index

c.) Assume a suitable maintenance factor

d.) calculate the number of fittings from lumen method of design formular.

e.) find the ratio of spacing to mounting height of fitting

f.) draw the layout of the fittings to a suitable scale.

In my next post i will explain these following terms:

Room index

Utilisation factor

Maintenance factors

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Thanks for following me.

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