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Flu lamp question
Were there ever any flu  lampsmade for 380 or 440 volts?  I mean proper ones with magnetic ballasts and starters
3 Replies
659 Posts
Not so far as I know. 
The highest voltage mass produced fluorescent lamps were the eight foot types, these just about work from 240 volt mains voltage with a series ballast. Operation from 220 volt nominal circuits is a bit marginal, especially if the actual supply voltage is on the low side.

I have seen standard types of fluorescent lamps worked in series pairs from nominal 380/400/415 volt circuits.

The usual combinations of lamp sizes and supply voltage are

110/120 volt circuits, any common lamp up to 2 foot in length or 22 watt circular. Longer lamps require either a higher voltage supply, or a ballast incorporating a step up transformer.

220/240/277 volt circuits, single short lamps as above (not preffered) Series pairs of short lamps. Single lamps up to 6 feet in length.

240/277 volt circuits, as above, and also 8 foot lamps.

Cold cathode fluorescent lamps use several thousand volts but can be used from any supply voltage by correctly specifying the leakage transformer.

The longer lengths of the newer T5 lamps run at a lamp voltage too high for a series choke on a 220/240 volt circuit, and could IN PRINCIPLE be used from 400 volts with a series choke, but in practice are invariably used from an electronic ballast.

At the factory where T5 lamps are made, the longer ones ARE lit briefly from a 400 volt supply via a special series choke, as part of the test/inspection process. Defective or out of tolerance lamps are thereby weeded out. The intended electronic ballast would be destroyed by the rapid switching from one lamp to the next. Use of 50 cycles rather than the high frequency from an electronic ballast also simplifies measurement of the lamp voltage and current.

Electronic ballasts can, by proper design, operate any wattage lamp from any supply voltage. From 6 volts, up to at least 480 volts.
3555 Posts
In principle it would be possible, and you certainly used to see mercury vapour bulbs (not tubes  as far as I know) run between phases for lighting  places like stadia, where the large size of the site makes voltage drop a concern, but quite often with the ballast ( which is really an impedance matching network if you like) at the bottom of the pole, often with adjustable taps to match the voltages. Nowadays they will be the more modern high pressure sodium or metal halide or some sort, and soon to be replaced by LEDs no doubt.
Rob Eagle
152 Posts
I wondered what a "Flu Lamp" was, now I know..


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