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| Category of work | Visual work characteristic | Minimum visual object size | The coefficient of the natural lighting | |
| if combined lighting | if side lighting | |||
| I | The highest accuracy | 0.15 | 3.5 | |
| II | Very high accuracy | 0.15-0.3 | 4.2 | |
| III | High accuracy | 0.3-0.5 | ||
| IV | Average accuracy | 0.5-1.0 | 1.5 | |
| V | Little accuracy | 1.0-5.0 | ||
| VI | Rough (very little accuracy) | >5.0 | 0.5 | |
| VII | Work with the light materials and in the hot factory sections | >5.0 | ||
| VIII | The general control for the industrial process | - | 0.5 | 0.1 |
Appendix2
TRAINING INSTRUCTION
on lighting determination using the luxmeter
The U-116 (Ю-116) or U-117 (Ю-117) luxmeter consists of selenium photo-cell with changing light filters and the galvanometer with the scale. When the light strikes the photo-cell surface, it produces the electric current, the strength of which is measured by the galvanometer. The galvanometer indicates the value of the researched light in luxes.
The front panel of the luxmeter also contains the switching buttons, and the scheme, that explains the effect of each button when using different light filters. There are two different scales at the device’s panel: the 0 – 100 scale, and the 0-30 scale. Each of them has the starting point of its measuring range marked: on the 0-100 scale that is 20, and on the 0-30 scale – 5. Also there is the screw-adjusted regulator for setting the device to zero.
The selenium photo-cell connected to the device with the plug is hidden in the plastic case. The spherical light filter, made of white light dispersing plastic and the opaque ring, is used with the photo-cell for more exact measuring. This filter is used simultaneously with one of the three changing filters. These changing filters have different attenuations (10, 100 and 1 000), and they extend the measuring range.
The process of the measuring consists of the following:
1) The device is set to 0;
2) By trying the different combinations of the pressed buttons and changing filters, the appropriate scale for the present light is found. When the button, next to which the ranges, divisible by 3 are written, the 0-30 scale is used. When the button with the ranges, divisible by 10 is pressed – the 0-100 scale is used;
3) The measuring result in scale marks is then multiplied by the attenuation value of the filter used.
The U-116 (Ю-116) or U-117 (Ю-117) luxmeter is graded for measuring the light, produced by the incandescent lamps. The correcting coefficients are used for the other types of light. For the natural light its value is 0.8, for the fluorescent daylight lamps – 0.9, and for the white lamps – 1.1.
The general assessment of the natural lighting in different premises is made by comparing the results of all measurements with the hygienic norms. The accuracy of visual work is the base for these norms. It includes the sizes of the visual objects, their contrast against the background etc.
For the convenience the results of measurements and the hygienic norms are written into the table:
| № | Figure | Results of determination | Hygienic norm | Assessment |
| 1. | ||||
| 2. |
To draw the final conclusion about the natural lighting of different premises it is necessary to compare the assessment of each result with the norm.
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