[Shop-talk] tube fluorescent wattage

[Doug Braun]

One of the things I read a few days ago about fluorescent bulbs said that some "Energy-saving" bulbs use less power, but their light output is lower, too, and the lumens-per-watt is often worse than regular bulbs.

And isn't the main job of a ballast to control the amount of current(and power delivered to the bulb?  So you could make an "energy saving" ballast that is no more efficient than a regular one- it just sends less current to the bulb, giving you less light output.

One other thing that occurred to me:  How can you easily measure now much power a fluorescent bulb is consuming, not counting the ballast? It's easy for an incandescent bulb: it is a pure resistive load and you simply have to measure the RMS current and voltage.  But the voltage and current of a fluorescent lamp probably have a complex waveform and phase relationship, and you would need laboratory-style instrumentation to accurately measure the true power.

And measuring a complete bulb+ballast fixture with a Kill-a-Watt style meter may not be very accurate because of the power factor of a magnetic ballast, and non linearity of an electronic one.

Doug