Energy Consumed by a Tube Light Ballast

Some host 25% savings between magnetic and electronic ballast. By in the real world is about 5% to 15% savings to go from magnetic to electronic ballast.

If you want to save electic change the ballast over to LED transformer and put in a LED light tube, your watts will drop from 35w to 6w. you can change 1000w mercury to 50w LED.

basic ohms law applies to both...do your own math, stop being so lazy

You can figure that an average decent quality magnetic type ballast uses around 10% of the bulbs rated power and a electronic one is around 5% of the bulbs rated power.

To be honest when you factor in the cost differences Vs the little bit of energy savings between the two its rarely cost effective to replace a older magnetic ballast with and electronic one just over perceived energy savings alone.

However if the old magnetic ballast needs replacing then yes going with a new electronic one instead is worth it.

Another advantage of electronic ballast is that the fluorescent tube can work with lesser voltage (say 80% of rated voltage) without flicker.

THIS gives some insight with figures to "Electronic Ballast" (perhaps i spotted a wrong 1 - i can see a coil on schematic - there should be something called ACTIVE INDUCTOR instead - would be more "Electronic")

Well, the lamps will still have coils. That is what supports the active emitter material where electrons jump from a solid material to a gas and back.

Some of these electronic ballasts are pretty cool. If you ever studied oscillator circuits and took note of the active Q value of the circuit, then you can see something very clever used in starting and running these lamps. Before the lamp lights, the Q is very low and the frequency generally climbs. But as the load kicks in, the Q goes up and the output voltage drops. It is all very analog but it works seamlessly.

In theory, none, but as others have said there is some loss. Please explain what you are trying to do. Your post is not clear.

As I was given to understand, ballast takes about 15 watts for the old type and about 5 watts for the electroniuc one. During the calculations for wattage of tube lights, usually 40 watts are taken for a 4 feet tube light and hence my question.

There have been suggestions from the members as to how I should go to basics etc. All said and done, there are quite a few things unexplained and not taken care of, and hence my question.

Anyway, as I could see the consumtion is about 4 to 5 watts only. And thanks