will these sensing lights work for a big hall-room with about 200 lights? or, like in a garments factory? if yes, then how? is it connected with switch?
Energy saving bulbs is too broad a term. The new LED (light emitting diode) lights are energy saving just like the fluorescent lamps. But the LED lights don't draw more energy if used long term or short term, so are better in overall efficiency. Still, the fluorescent lights, whether the old tube style or compact blub style are plently efficient, don't worry about the minor extra wattage consumed during startup. Buy the LED type when their price comes down.
Sensing light by light dependent reisistors or by photo diodes is done either to put on/off the light automatically depending on the presence or absence of light or for dimming the light. For both these applications one can control only on one lamp or a group of lamps or all the lamps. The difference is only in the selection of appropriate relays or contactors and the placement of light sensing elements. Photo resistors (CdS) or photo diodes can sense visible light from tube lights or incandescent lamps
