Optimising Plant Lighting Voltage

Has everything else been done first?

http://cr4.globalspec.com/thread/77660

Define "plant lighting".

I don't really want you to, I'm pointing out that this is a broad brush statement that in the real world, means next to nothing. So if you start with an ambiguous statement, any claim you make based on it cannot be proved or disproved. Such are the tactics of scam artists.

IN GENERAL, if you lower the voltage in a purely resistive circuit, you lower the power consumed in that circuit. But at the same time, you also lower the OUTPUT of that circuit, i.e. the "work" performed. In the case of an incandescent lighting circuit, where all of the lamps are resistive elements, that means you reduce the temperature of the filament and thus reduce the lumens that each lamp produces. If you had put in too many lamps, take some out. If you put in lamps of a higher wattage than necessary, use lower wattage lamps. Same effect: less light, ergo less energy.

But modern "lighting" systems are almost devoid of incandescent lamps now, we have moved to more energy efficient lighting, such as fluorescent, sodium vapor, metal halide etc., even LEDs. So when you begin to reduce the voltage indiscriminately in an effect to "save energy", you may actually end up causing harm to the equipment.

Bottom line, you cannot make broad brush statements about saving energy with any single magic box. Everything must be investigated on a case-by-case basis, which is where PWSlack was getting you to think about by pointing you to a previous thread on doing a thorough STUDY of your electrical energy needs. That is always step one. But the scam artists would have you believe that this is unnecessary, that their box will make it simple and quick, requiring no thought or input from you. Hence the "magic".

GA

because if we reduce / optimise voltage , then the current should increase. Yes or no??

For the same output on a reactive load yes...but transformers can also lift the voltage and reduce your current ergo less losses.

If your lamps are resistive then you are just reducing the output power if you lower the voltage.