Getting the most from Automatic Lighting Controls


Siting the Controls for Best Usage
Above is a drawing representing part of a building. The various rooms are labelled with their functions and the most suitable sites for the different variants of Greenlite controls will be mapped and explained in detail in the following paragraphs. The red circles only indicate the coverage of the units and are not calibrated. All units and systems have PIR occupancy detection, Photo-Darlington light level detection and Active Infra-Red configuration and control.

The Sales Office (12ft. x 10ft.) Small rooms like this can often be covered by a single CCU1, combined ceiling unit. This stand alone control has a range of 2.5 times the ceiling height to a maximum of 7 metres diameter and is omnidirectional. The switching capacity is 8 Amps inductive and can easily handle a couple of standard twin fluorescent fittings which would give more than adequate illumination here. The unit should be fitted directly above the desks and as central to the room as possible.

 

The Kitchen and Toilet (Total 9ft. x 10ft.) These rooms are even smaller than the office, and each has only one fluorescent fitting, so again the CCU1 is the most suitable option mounted as centrally as possible in each room. However, as the CCU1 switches using a relay, it allows both CCU1 outputs to be commoned together to feed both fittings. Thus, when the toilet is occupied, the kitchen light also stays on and vice versa. The former is very desirable and the latter is no real penalty. This of course can only be used when the same live source feeds both fittings.

The Main Office (13ft. x 13ft.) This room is slightly bigger than the sales office but can still be covered by a single CCU1. The maximum sensitivity is directly beneath the sensor, so, providing that the desk is near the centre of the room, then areas up to the 7 metres maximum are no problem. If the desk were sited to one end or corner then in order to ensure that the lights would behave correctly the hold-on time may need to be increased. This hold-on time is the time delay between the last occupancy detection and the actual switch off of the lighting. Normally this would be left at the factory setting of 4 minutes, but 8 or 16 minutes delays may be selected instead.


The Workshop (20ft. x 11ft.) The lights in the workshop are in two rows parallel to the main windows. As the window area is so large in this room and the room itself is also large, a CWU1, combined wall unit, as it can cover a 12 metres area at 120 degrees, is used in the corner by the window. The version of this stand alone unit used, the CWU1/2 has 2 relay outputs of 8 Amps inductive capability each independantly controlled by their own light level. As the ambient light level falls the lights by the inner wall come on first and if the light level continues to fall the lights by the windows come on. The two rows of lights are both occupancy controlled as well. On all units and systems the light level control may be removed and the units set to occupancy only. Light levels are set by the installers or the customer when the appropriate ambient light level is reached using the infra-red control system.

The Stock Room (12ft. x 11ft.) The stock room is a small room with six sets of racking around the walls. A CCU1 is used in the centre of the room and this is adequate even though the racking and the stock on the racks could mask personnel from the sensor. The small size of the room means that the masking effect would be very limited and any problems could be removed by adjusting the delay time. The sensor has direct line of sight of the door and would always trigger when the door was opened.

Stores (18ft. x 12ft.) In the stores the problem of racking is more troublesome. The size of the room is more suitable to a CWU1. This, however, would be severely masked by the racking. A single CCU1 will not cover the area. The depth of the room would suit a two light zone unit but a wall unit cannot be used. Two CCU1s linked as for the kitchen and toilet would do but there is a better solution. The Area Control System. This normally consists of an SPC1, system power controller, plus an SMS1, system master sensor, plus up to ten of either SCS1 or SWS1, system ceiling or wall sensors as needed to cover the area concerned. A special system, an SPC1/2L, an SMS1L and an SCS1, is used here which is capable of light zoning as per the CWU1/2. The SPC1/2L has the same two 8 Amp relays and also houses a 12 volt power supply which powers the sensors. The master sensor is above the desk to give control to the storeman and sample the ambient light level, and the one slave is near the door.

The Lobby and Corridor (47ft. x 6ft max.) The lobby and corridor, because of the awkward size and shape, is another case for a system. This is a standard system for there is no advantage to light zoning. A master sensor is used to cover the lobby but a wall sensor covers the corridor because the shape matches the distance of the wall unit. One feature of systems, known as corridor link, enables one system to act as an input into another systems’ master sensor. Thus, if the corridor is required to be lit when the offices are lit, the offices would be fitted with minimum systems (one SPC1 plus one SMS1). The low voltage corridor link would then turn on the corridor lights when the office lights were on, but NOT vice-versa. This one-way light control is also used in open plan situations with a ‘notional’ corridor and set open areas.

The rooms depicted here are actually part of Greenlite Controls Ltd. and potential customers are welcome to visit by appointment and see these units and systems in action. Please contact sales for more information.