Lighting Maintenance: Unless a lighting installation is properly maintained, lamp depreciation and dirtee accumulation on the fittings will case an increasing loss of light, in some circumstances this can cut he illumination level by half in the space of only few months.
When choosing equipment, make sure that it will be easy to clean and re-lamp and also provide safe and ready means of access.
Cleaning Schedules should be carefully planned fittings; should be cleaned a regular inter and not just when a lamp fails.
The need for this is often overlooked because dirt collects so slowly and every that a deposit which may be absorbing a large proportion of the light is often difficult the defect until it is distributed.
Cleaning should be done often enough to prevent he illumination level from dropping more than about 2 – 30% during the interval. A systematic check with light meter at several fixed pints in a n installation is one way of deciding how often to service it.
Using ultraviolet light = Ultraviolet light cause certain substances to fluoresce brilliantly in a darkened room. Typical uses are for the detection of fine surface cracks and the revelation of otherwise invisible marks.
Magnifying minute detail for Lighting Maintenance
Details just too small to be seen comfortably with the naked eye can be made much readily visible by using a low-power. Magnifier. Proper lighting is also important, but with minute visual tasks of this kind, size of detail is the dominating factor and a mere 1.5 times magnification may be more beneficial than a hundred-fold increase,
When small objects have to be seen, background which contrast in brightness are much more effective than those which merely contrast in color, since the eye cannot readily distinguish the he of very small objects.
The main classes of task requiring an contrasting background (or illumination from behind) are those in which the outlines of the object are important, and that involving examination of transparent or translucent objects.
It should be noted particularly that bright backgrounds are only suitable for translucent objects, or work in which the boundary of the task harder to see, and if these are important( as is usually the case) a pan, unobtrusive background slightly darker in tone than the work itself is much the best choice.
Objects moving irregularly or unexpectedly in the workers genera filed or view ( e.g. Machinery which starts or stops at irregular intervals, the moving hands of a worker seated opposite, flashing or flickering lights, etc.).
These can cause severe distraction, and should not be permitted within 450 of the line of sight when the gaze is fixed in the task.
Lamp replacement should also be done systematically, and it is not always advisable to wait until they actually fail to light. The output of an incandescent lamp does not drop a great deal before it finally buns out, but this is not necessarily true of the fluorescent type, which may continue to strike long after the light output has dropped to a very low figure.
To estimate the depreciation in light output of fluorescent lamp, their brightness may compared with that of new (100 hour) lamps of the same type. A simple light-meter can adapted for this purpose with the aid, of a small hood, the mouth of which pressed against the lamp at a point about half way along it.
Group replacement of a the lamps together at some presentation .of time is often favored to large installations ill which many units are in use for approximately the same number of hours each day. This group replacement takes place after the installations has burned for a fived number of hours, or after some fixed proportion (say 20%) of the lamps have failed.
Special techniques for Lighting Maintenance:
The majority of factory and office takes can performed efficiently and safely under lighting provided by conventional means. In certain cases special lighting techniques or equipment required.
Some typical instances are described below
Examining shiny surfaces- As explained earlier; the Special techniques of lighting visibility of polished metal surface depends upon; what they reflect rather than the more even of illumination falling on them. The same principle applies to other kinds of shiny surfaced work; even when it has only a sight glass (e.g., Back leather); and details can often best revealed by arranging the work.
Catches the light Detecting surface irregularities- A beam of light skimming a surface will make; small surface irregularities cast shadows; which clearly reveal their presence. This usually calls for a directional beam of light such as that provided by an internal reflector lamp; or a row of such lamps arranged to give a broad beam.
Glare assessment and control
As already mentioned glare mainly caused by light emitted at or near the horizontal by inadequately screened amps. Screening can done either with opaque shades and louvers; which hide the amp altogether throughout the critical range of angles brightness to more comfortable proportions.
Glare control by shielding:
The key point is that closer a glaring light source approaches the observer’s line of sight, more sources approach the observer’s line of sight, the more troublesome it becomes. The late afternoon sun provides a striking illustration of the enormous increase in glare which occur when displacement angle D becomes very small.
Reflected glare in Lighting Maintenance:
The term reflected glare commonly used to describe the variety of ill effects produced by unwanted reflections appearing in hand around the work. The term is somewhat misleading, since such reflections are rarely bright enough to produce discomfort glare of the kind discussed in the previous section, and they general interfere with visual comfort and efficiency in quite a different.
Diagnosis and remedy of complaints:
The procedure is as follows from the working position; sight a distant object at eye eve and then momentarily screen the fitting from vie as shown. If this action enables details in the object to seen a little more clearly; or makes seeing even slightly more comfortable the installation is probably creating enough glare; to cause serious discomfort to people forced to work under it for long periods.
The above mentioned test should always applied when the occupants of an office complain that too much light since the phrase frequently used by those working under excessively bright lighting units.
Inadequate upward light:
Inadequate ceiling illumination has the disadvantage of making an interior appear rather gloomy and may even increase eye fatigue. People’ who work in an isolated pool of light in the mid die of a darkened interior; have to read just their eyes very time their gaze shifts from the brightly it work point. This can cause considerable fatigue and satisfaction when the visual work prolonged and exacting one.
Unsuitable color treatment for Lighting Maintenance:
For obvious reasons, excessively dark finished on ceilings and other main interior surfaces; can produce much the same ill effects as inadequate upward light. In factories, poor colors treatment is generally; the result of neglect but in offices excessively dark colors; sometimes deliberately used for decorative purposes.
Flicker and stroboscopic effects:
All lamps operating of alternating current produce light, which pulsates at twice the supply frequency. Whist this presents no problem in the vast majority of cases; a few isolated individuals who are particularly sensitive to this fickler; may be seriously distributed by a pulsation in the task brightness which is too sight; and too rapid to detected at a by most people. Complaints of this kind only arise when a light comes from amps on a single phase of the eccentricity supply; and can cured by running adjacent rows of amps of different phases.
Interior colour treatment for Lighting Maintenance:
No lighting scheme can be fully effective unless we chosen; (and well-maintained) finishes provided on main interior surfaces such as ceilings; was, plant and equipment. Here the main object is to use colors, which will reflect rather than absorb light.
For ceilings, the reflection factor should be at least 75% which mean whit or near white. A matter finish preferable (aluminium pain not recommended) Side 30.
Walls best finished in light pastel colors in the 50 75 % range; except in the case of very brightly lit walls(e.g. Those adjacent to a large window ); which may need toning down to 40% or less to prevent them from becoming to glaring. Conversely walls containing window (but which receive no direct light themselves) can often be painted white with advantage.
Furniture should preferably have a reflection factor of at least 20%; and the modern blend wood finishes and light Gray paints for steel cabinets; greatly to preferred to the old-fashioned dark stained wood; and dull live green finishes which used to so frequently use.
Floors should be reasonably light in colour. Practical consideration usually governs the nature of a floor in finish, but 20-25% or so is generally a satisfactory figure. Floor finishes which are very much lighter than this should be treated with particularly well lit office interiors).