Lighting Capacitors ?

There are wide value of lighting capacitor, range from 4 uf to 50 uf. but I am not sure which value to pick for my 40 W fluorescent light run in 230 volts ac. Can any person help me in this . Thanks and Regards

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Lighting _capacitor?_ None of my line-operated fluorescent lamps has a capacitor. I suppose one could use a capacitor instead of the usual inductive ballast, but I've never seen it.

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Stephen J. Rush

Most I've seen used a 3.3uF (as PF correction)

Cheers ............. Rheilly
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Rheilly Phoull

I have seen capacitive fluorescent lamp ballasts.

Sometime in the late 1970's, I saw in the trash an already-antique fixture with a "lead/lag" ballast - with one lamp leading and one lamp lagging.

Sometime in the early 1990's, I got a 3-4-or-so-watt plug-in fluorescent "nightlight" with a capacitive ballast.

Sometime in the mid 1990's, I got a 20 watt super-slim fluorescent fixture of the Lights of America brand.

In all of these cases, some inductance was added in series with the capacitor. Otherwise, the current waveform would be a spiky one with high peak current, resulting in reduced efficiency (the low pressure mercury arc is nonlinear in producing shortwave UV) and extra wear on the electrodes.

That lower wattage plug-in light now buzzes like mad - the inductor must have become a little unglued. I never did use it much - that's why it still works at all after a good 15 years.

- Don Klipstein (

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Don Klipstein




Don haven't done any homework on this yet but your post gets me thinking/questioning. About capacitive versus inductive reactance fluorescent light fixtures. Fixed plenty of two tube (115 volt 60 Hz.) fluorescents; not sure what's inside the ballasts and with an ample supply of used spares we just replace bits as necessary using same colour codes of wiring! But also have several older 3 tube fixtures that seem to have been modified/botched up, haven't analysed their circuitry yet. They need quite a bit of TLC/repainting etc. if ever worth getting around to it! Also cooking stove fluorescent lamps seem to employ a single winding inductor about the same physical size as a tube radio output transformer, in series with the single (typically 24 inch) tube. Inductive reactance? Best scrounge though has been a 40 foot plus row of electronic ballast fixtures that are now on ceiling of basement workshop!All we had to do to install and get them working was $25 of T10 tubes IIRC. Only problem was getting permission to take the fixtures, mostly in good condition the job foreman wanted us to take the whole lot; which would have required a dump truck. We settled for 7 four tube, 8 foot fixtures in back of our pickup! So that gives us a couple of spare fixtures. Any comments appreciated. Always willing to learn something. terry

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