View Full Version : Do dead florescent lights use electricity?
06-03-2007, 07:18 PM
Do florescent lights draw current even when they are burned out? With an incandescent light it is obvious that when the filament breaks the circuit is open and no current flows. But what about a florescent light fixture. Does the ballast keep trying to light the burned out tube? Also if I leave the fixture powered but remove the bulbs does the fixture still use current? Thanks in advance to whomever answers this for me.
06-03-2007, 07:32 PM
Yes, they do consume energy. The ballast is a transformer, and so long as the primary winding is continuous and supplied with voltage, it will consume energy.
06-03-2007, 07:36 PM
The ballast is a transformer...
No, it's an inductor (in the case of a magnetic ballast). There is no current flow through it if the bulb is dead or missing.
06-03-2007, 07:40 PM
Also, you will sometimes see these where the tubes are trying to light (flickering) or one is lit, but very dim. In such cases, they are using additional electricity to do that. I believe that the flickering mode actually uses more energy than if it was fully lit (in addition to putting a lot of wear & tear on the starter).
As a small nitpick, it's fluorescent.
06-04-2007, 06:41 AM
No, it's an inductor (in the case of a magnetic ballast).
Actually it's both, a transformer is 2 inductors that are placed together such that the magnetic field induced by the primary (powered) inductor induces a current in the second - by changing the number of 'coils' or 'loops' of wire in the primary inductor vs. the number of 'coils' of the secondary you get different voltages, which is how a transformer works.
Transformers of this type do consume some current even when the secondary is open. Though inductors main 'resistance' is called impedance and does not produce a energy loss there is also real (energy consuming) resistance in the wires.
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