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Re: [APD] Custom Sealife Ballast Replacement...help plz

I'm going to oversimply to avoid all the grisly details --
fluorescent lighting is rather complicated in a wonderful
but to most folks boring kind of way. 

The total watts rating on the Fulham has more to do with
the total amp load that it can safely handle. It doesn't
mean that it will operate at that current level -- unless
the bulbs conected to to it have particular

How the ballast performs is more like this:
A Fluorescent bulb has a lot of resistance when not lit.
After it warms up (which the filaments on the end of the
tubes take care of, a tiny bit of mercury in the bulb (a
bit less than a drop) vaporizes and the gas inside the tube
then becomes conductive in a weird way -- it becomes a
plasma. What that means for this discussion is that, the
more juice you give it, the lower it's resistance and the
more current it will try to draw from the power supply. A
Pyrrhic glutton for energy, it would just turn into an
electrical runaway and flame out unless something limited
the current. Thus, a ballast is needed to limit the current
-- and hence, the term "ballast." The ballast also partly
determines the voltage across the tube pins and that
voltage will be partly a function of how the plasma behaves
and how much current it is allowed to get. So the tube and
the ballast together determine how things work with
fluorescent lamps. This also means that bulbs will operate
under diff conditions, at diff voltages and current levels
and there is some flexibilbity in how well a ballast and
bulb have to match up.

There is much more diff between straight pin (4 in a row)
and square pin (4 arranged in a square) bulbs than between
65w and 55w bulbs. The diffs between the diff pin
arrangements are mostly the starting and running voltage
requirements. ONe needs a higher voltage to start but I
forget which -- I have it written down around here
somewhere :-\

For Fulham ballasts, treat the twin tube 65w bulbs as if
they are 55w bulbs. I believe a Workhorse 5 will run a pair
of the 65ws just fine and I'm sure the 6 will run a pair of
them with no trouble.

Good luck, good fun,
Scott H.

--- David Terrell <Dave at TerrellClan_com> wrote:

> S. Hieber wrote:
> > If the bulb test out significantly dimmer than before,
> you
> > can probably achieve very clsoe to the same brightness
> by
> > using perhaps 55watt bulbs.
> > 
> > 
> > Is Workhorse 6 the ballast that Fulham recommends for
> the
> > bulbs you have? I would have thought maybe a 5 or 7.
> > 
> > 
> > sh
> You're right, I had another look after I got home tonight
> and it seems 
> perfectly normal light.  But, I'm human...
> Fulham recommended the 5 and 7, like you said.  You know
> your ballasts 
> well!  But!  There is no option 2x65W from their ballast
> finder.  So I 
> used some simple things to select the 6...the fact that
> its 140W output 
> had me, then I looked up the wiring diagram and figured
> out that it 
> wouldn't be dangerous to use that with 2x65W...in fact,
> theres no 65W on 
> that list.  So I didn't know what to do, but this is
> working.  Would 
> there be something wrong with using the 6 vs the 5 or 7? 
> I can still 
> turn back with one of them.  I'll take the loss if its
> dangerous...
> -Dave
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