The installation of light switches and other electrical parts need to take into consideration a number of factors. For light switches, the following requirements must be incorporated into the design drawings and the specifications.
1) The grouping of lighting luminaries into single control should be done in small groups or on individual luminaries. This should be arranged in such a way that unnecessary lights can be switched off while allowing sufficient luminaries to be operating efficiently to give the required level of light over the working space where the activities is ongoing. This is part of the overall effort to lower the operating cost and conserve energy.
2) Where group switching are implemented, clear identification should be provided near the switch to indicate the lighting area controlled by a particular switch. For example, if a switch controls a number of light fittings over the main entrance of a lobby, then a label indicating “MAIN ENTRANCE” should be provided at the switch.
3) Switches should be provided at accessible locations that are within the line of sight from under the light fitting controlled. Exceptions to this are usually enclosed staircases and corridors used by the general public. For these areas, the location of the switches is selected to prevent abuse or unintentional operation by members of the public. Control of lighting for these types of spaces should be done by someone who is in authority over the area concerned.
In many cases these switches are located inside locked electrical rooms. In more advanced designs, these lights are controlled by a timer or the building control system so the lights are automatically switched on and off without human intervention. A manual bypass switch is usually provided where automatic controls are implemented.
In those parts of the world where the climates are seasonal, some form of sensors (eg. daylight sensor) is also commonly utilized.
4) The grouping of the lights should be so arranged that they can be switched off parallel to the windows. This will allow the row of lights nearer to the window can be switched off when the effect of daylight from outside the building is already adequate for the activities in the room.
5) Further control in the levels of lighting should arranged by the use of alternate switching. For example, in a row switching arrangement, alternate luminaries in the same row should be grouped under the same switch. In this way it is possible to switch off half the lights (thereby reducing half of the energy consumption) while maintaining a reasonable uniformity at the same time.
This method can be taken further by arranging the grouping to give a three or four lighting levels. For example, the corridor lighting at hospitals can be arranged into three alternate switching groups. After 7 pm one of the three groups of lights will be switched off, reducing the energy consumption by all corridor lights throughout the hospital by one third. That is a significant amount of kWh for large hospitals.
After midnight, the second group of lights will be switched off, reducing the consumption by a further one-third. That means after midnight only 33 percent of the corridor lights will be “ON”, and these lights are one of three alternately throughout all the corridors.
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