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Re: Flourescent lights in series
Tyrone Genade wrote:
> On 11 Jun 2001, at 7:07, Wright Huntley wrote:
> > BizEcology at aol_com wrote:
> > >
> > > If I remember my old electrical shop correctly, if a group of devices are in
> > > series, the voltage will drop at each device. Also, if one fails, the entire
> > > series will fail. I believe the lights should have been wired in parallel.
> I wanted || but the electrician I spoke to said that it was far to
> complex and that series would work. I wired the outfit in series as
> per instruction from various sources (no less the instructions on the
> actual ballast). How would you do it in series?
> > Correct, but fluorescents are more complicated than that. They are a gas
> > discharge device that need a means for getting the gas to ionize (heater, hi
> > voltage, etc.) and the voltage (starting and running) is highly dependent on
> > tube diameter as well as length. It would be a real coincidence if all those
> > conditions were met by a single ballast, and the ballast was able to
> > restrict current to a proper range.
> Ah ha....
> > Use 20W X2 ballasts and save the 40W ballast for its proper (usually 4')
> > tube.
> I'll be more inclined to try a 50W first as refitting for 2 20W is going
> to be too much trouble (which is why I went this way in the first
> place). In esscense this should of worked. I have 2 18W tubes off
> one 40W ballast etc... as per spesification. Some where something
> is wrong...
> Tyrone Genade
Don't mess with ballasts not specifically designed for the lamps you are
using. If your lamp is listed on the label, and the ballast and lamp are
good, they will work when wired as on the label. Otherwise, you will either
greatly shorten the tube life, get inadequate light out, or cause other
Ballasts and lamps are desigened to match. There are essentially three kinds
of lamps and three (different) kinds of ballasts.
Pre-Heat (Slow) start, Rapid start and Instant start lamps are all somewhat
different. Rapid start lamps can often be used with Instant start ballasts
(the all electronic ones). Many rapid-start ballasts are hybrid electronic
magnetic, and you must wire the filaments properly. They are shorted
together for Instant Start operation.
Lamps come in different lengths and diameters, too, which has a profound
effect on how they will work with a given ballast.
Pre-heat and Rapid-start lamps have filaments to be heated to generate
enough electrons to sustain a discharge. Instant start lamps have only a
single pin at each end, and count on an initially very high voltage to cause
a discharge and the discharge current to heat the ends for sustained
operation at some lower running voltage.
You can hook tubes in series, or you can hook filaments in series (and tubes
in parallel), if the ballast (magnetic or hybrid) provides enough voltage to
heat the filaments. I would not try this. It is too easy and cheap to do it
right (and safely).
Before you continue down this path, Tyrone, go to one of the excellent web
sites that teaches all about fluorescent lighting. [Sam's F-Lamp FAQ at
http://www.misty.com/people/don/f-lamp.html is a good place to start.] This
stuff is truly deadly, and we do need you here to pick on about religion,
etc. ;-) A 50W ballast is no more likely to work than a 40W ballast, if the
filaments aren't being supplied and/or the voltages are incorrect.
A ballast that is *not* lighting the tubes probably has very lethal voltages
wandering around, looking for a place to short to the case or you.
General Rule: Mismatched tubes and ballasts should be treated with the
greatest of caution. Know *exactly* why you are doing it, and the possible
consequences before you go that route.
You should be able to buy a single 2X20W ballast (or a 3 or 4-tube one that
will operate with only 2 tubes).
AH Supply sells some excellent "Made in China" electronic ballasts that will
operate a surprisingly wide range of lamps in "Instant-Start" mode. Buy them
there, if you must tinker, as Kim provides superb advice. He also provides
the excellent hardware to do it safely.
Wright Huntley, Fremont CA, USA, 510 494-8679 huntley1 at home_com
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for the general welfare but only those specifically enumerated."
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