I read information about fluorescent lamp and compact fluorescent lamp (CFL) but I still don't understand why CFL saves energy and produce the same amount of light?

Maybe the electronic ballast consume less reactive power than the traditional ballast?

  • 5
    \$\begingroup\$ Saves more energy compared with what? Incandescents? Large fluorescents of thirty years ago? LEDs? Sitting in the dark? \$\endgroup\$ Jan 6, 2016 at 14:53
  • 5
    \$\begingroup\$ Candles, man. Candles. \$\endgroup\$
    – Transistor
    Jan 6, 2016 at 14:57
  • 1
    \$\begingroup\$ A standard incandescent lamp creates light by heating a filament to very high temperature. Most of the energy used in heating the filament is wasted as heat - only a tiny proportion of that energy is converted to light. \$\endgroup\$ Jan 6, 2016 at 15:08
  • \$\begingroup\$ @PeteKirkham Compared with Large fluorescents. I want to compare the ballast with the magnetic ballast. \$\endgroup\$ Jan 6, 2016 at 15:13
  • \$\begingroup\$ Incandescent lights are heaters that produce a bit of light on the side. Fluorescents and LEDs are lights that produce a bit of heat on the side. If your goal is to produce light, Fluorescents and LEDs are more efficient. If your goal is to produce heat ... \$\endgroup\$ Jan 6, 2016 at 16:32

2 Answers 2


You question is not so clear but is seems that you're asking why is a modern compact CFL lamp more efficient that the old fashioned CFL tubes ?

This is easy to answer if you just sit down and think about it for a moment. What happens when something is inefficient ? Energy is lost, well not lost but it is converted into heat, not light. So something less efficient (tube CFL) will produce more heat than something more efficient (compact CFL).

Now what get's hot in the tube CFL ? The lamp itself, yes but this also happens for a compact CFL. What can get really hot is the magnetic ballast ! Also notice the size of such a ballast, it would not fit in a compact CFL ! So compact CFLs use an electronic load, which also does not get so hot so obviously it is more efficient.

In your tube CFL you could replace the magnetic ballast with an electronic one and so improve the efficiency.

  • \$\begingroup\$ Do we already have an answer on here about what's actually in the ballasts? \$\endgroup\$
    – pjc50
    Jan 6, 2016 at 16:14

Flouro lamps are actually more efficient at say 30KHz than 50Hz .The efficiency curve doesnt keep increasing ,it kind of limits out .This is why you tend to not see stuff in the MHz range despite it being technicaly feasible .The electronic ballast makes the tube itself more efficient .Even if you use rubbish for the electronics your overall efficiency should be better than a standard 50Hz ballast.


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