Magnatek ballasts, and other ballasts.
Arthur Johannson asks about Magnatek Ballasts in APD #244. I do not have my
catalog at hand, so I am answering his question from memory - a risky
endeavor! However, I believe he is describing a very common type of
"magnetic" ballast. Magnatek is a very well-known brand of magnetic
ballasts. They are well made. Ballasts seem to be poorly understood, and the
differences between the various kinds are also poorly understood.
I will stick my neck out, and try to describe how ballasts work, and the
differences between them. Again, this is risky, as it is a lot easier to
describe these devices with drawings. Also, I am NOT an engineer. This will
not be as organized nor as clear as an Engineer would say it, but I will do
The "ballast" for any fluorescent bulb is mostly a CURRENT limiting device.
Once the "arc" is started between the ends of the tube, an essentially
unlimited direct "short circuit" is developed. The best illustration that
immediately comes to mind is a bolt of lightning. Lighting does NOT just
suddenly blast a giant spark from cloud to ground. First, in an EXTREMELY
SHORT TIME just before the bolt of lightning, an "ion trail" is established
between the cloud and the earth. In other words, a "pathway" is established
in the air, the pathway made up of "ionized" molecules of the gases that air
is made of. Then, the giant "spark," the actual "lightning bolt" follows that
pathway in an enormous burst of energy. The loud "Bang" is generated from
the suddenly heated air as the spark jumps from ground to cloud. (The main
"bolt" most often actually jumps from the GROUND up to the cloud, not the
other way around.) The arc in a fluorescent tube is similar, in that it must
be controlled to keep a sort of miniature "lightning bolt" from ruining the
Now I will 'backtrack' a bit. If you could take the white "phosphor" coating
off of the inside of an ordinary fluorescent bulb, you would see that there
is a "filament," a tightly coiled wire, that runs from one of the pins in the
end of the bulb to the other pit at that end of the bulb. There is a
"filament" on BOTH ends of the bulb. They are usually covered with a whitish
powdery stuff. The powdery stuff is a material that "boils off" lots of
electrons when heated. The filament is the thing that actually "fails" when a
fluorescent bulb wears out. Either the filament burns out, or all of the
powdery stuff has "boiled off"
What is in the clear space from one end of the bulb to the other? That
depends upon several Engineering decisions made by the folks that designed
that particular bulb. However, it is ALWAYS a pretty good vacuum, with a
SMALL amount of some gas or other. If you look at a Neon sign that is not
lit, it has a pretty good vacuum, with a teeeny tiny bit of Neon gas. It
looks like just "clear glass" until it is lit. When an arc of electrons
passes through that gas, it GLOWS with the familiar reddish orange "NEON"
color. In the fluorescent bulb, you get an arc that generates ULTRAVIOLET
LIGHT. The Ultraviolet from the arc bangs right up against that white powder
that coats the inside of the bulb, and the powder GLOWS. Electricity passes
through the very thin, almost a vacuum, gas in the bulb, generating
ultraviolet light, which bangs into the powder, which generates VISIBLE
light. Ultraviolet light has a very short wavelength, and WE cannot see it.
(Bees and many other insects, on the other hand, have really TINY eyes, and
they see ultraviolet light just fine! In fact, flowers (that show pretty
colors to our big eyes) reflect the Ultraviolet light in sunlight very
strongly, and appear "bright bee white" to a honey bee. We see colors, they
see "white.") ( :-) )
When a fluorescent bulb is "started," one or both of the filaments at the
ends of the bulb is heated by electricity, and "boils off" a cloud of
electrons, which quickly moves down the tube until this cloud of electrons
fills the bulb. (actually, the electrons "ionise" the gas in the bulb, just
like the ion trail that forms the path for a lightning bolt) Then the arc
jumps from one end of the bulb to the other, and the bulb is "lit."
Without the ballast, the arc would be a direct "short circuit" between the
ends of the bulb, and a HUGE blast of electricity would jump through the
bulb, and it would either instantly burn up the filaments, or the bulb would
literally explode. Rather like the lightning bolt I mentioned earlier. An
uncontrolled arc through a fluorescent bulb is BIG trouble for the bulb!
Actual bulb explosions from a "shorted ballast" are very rare, but they can
happen. Most often, if the "ballast" in a fluorescent fixture fails by
shorting out, you hear a loud "pop," accompanied by a very bright flash from
the bulb, then nothing. No noise, no light. The bulb has burned out.
(Actually, the filaments were destroyed by the suddenly uncontrolled big
The ballast regulates, or controls, the flow of current through the arc, one
way or another. The magnetic ballast literally "chokes" off the current at a
set point. It does this by taking advantage of some basic physics. Remember,
the electric power in your home is (depending upon what country you live in)
either 50 or 60 cycle alternating current. In a "cycle," the flow of
electicity goes from no flow at all, up to a set voltage, then back to zero,
then goes THE OTHER WAY, from zero up to the set voltage, then back to zero.
The current in that arc in the bulb does the same thing. It goes from zero
to maximum, back to zero, then the other way, then back to zero. The
ultraviolet light from the arc also goes from zero to maximum, back to zero,
up to maximum, then back to zero. The glow from the phosphor powder coating
the inside of the bulb does the same thing, except the powder never
COMPLETELY stops glowing.
An alternator, for example the one in your automobile, often spins magnets
inside a set of coils of wire. Any time a wire moves through a magnetic
field, it generates an "ElectroMotive Force," a force measured in volts. The
amount of the force (voltage} depends upon how strong the magnetic field is,
and how FAST the wire moves through the field. Or, you could move the magnet,
and let the wire stand still. It does not matter which is moving, the
magnet, or the wire.
If you pass a current of electricity through a wire, it generates a magnetic
field. Since one of the most basic Laws of Physics can crudely be stated as
"There ain't no such thing as a FREE lunch," that magnetic field is exactly
OPPOSITE to that magnetic field that we were moving the wire through just a
moment ago. If the ends of the wire (or the ends of a coil made of many
turns of wire) are connected, an electrical current is generated when you
move the coil through a magnetic field. Or, you could move the magnetic
field past the coil. Is does not matter which is moving. Yes, I suppose you
could move both of them at the same time if you wished. ( :-) ) And, any
time an electric current moves through a wire, it generates a magnetic field.
The most difficult concept for most of us is, BOTH THINGS HAPPEN AT THE SAME
TIME. You generate a current in the coil of wire by moving it through a
magnetic field, and then that current in the coil of wire generates another
magnetic field. That magnetic field is exactly OPPOSITE to the magnetic
field you are moving the wire through to generate the current. The magnetic
fields "fight", as does the current. I did not say that particularly well.
In a magnetic ballast, the rapid changes in current direction (the "cycles
per second," or "Hertz") makes equally rapid changes in the magnetic field
generated by the coil of wire in the ballast. The magnetic field reverses 120
times a second. (Each "cycle" or "Hertz" goes from zero up, than back to
zero, then the other way, then back to zero.) The corresponding current in
the arc in the bulb is doing the same thing.
The "fighting" magnetic fields and currents in the magnetic ballast "fight"
much stronger as the amount of current flowing through the ballast increases.
This "fighting" impedes, or chokes, the current flow. An individual ballast
is designed by the Engineers so that it will let just exactly the right
amount of current through to light that particular fluorescent bulb, but not
let too much current through. It gets hot from the effects of the "fight."
That heat is totally wasted electricity. You pay for it, but you don't get
any light from it. Magnetic Ballasts are lots simpler and cheaper to make
than Electronic Ballasts. That is probably why they are used so much.
Now, lets go to the actual generation of the light. The white coating on the
inside of the tube, the phosphor, glows from the ultraviolet light generated
from the arc. The arc goes from zero, up to a maximum, then back to zero,
then the other way, than back to zero. So does the Ultraviolet light. So
does the light from the glowing phosphor! The phosphor is a bit goofy,
though. It does not quite stop glowing between current pulses. It almost
stops, but not quite. If you are in a dark room, you can wave your hand under
a SINGLE fluorescent bulb, and you will see multiple hands, as the light
turns on and off and on and off, following the current cycles. A "strobe"
light turns on and off very abruptly and completely. The fluorescent bulb is
kind of lazy, and does not turn either on or off all that quickly. Its
brightness depends mostly upon a combination of the phosphors used, and upon
the amount of current flowing through it. Too much current, and the
filaments will burn up. Too little, and you don't get much light.
In a common magnetic ballast, you start the arc by flowing a current through
the filaments, heating them until enough electrons have boiled off to "start"
the bulb. Once the bulb is started, the filaments stop glowing, and the
light comes entirely from the arc. Starting a "pre-heat" bulb can be
accomplished by using the common "starter," which looks like a very small
aluminum can with two pins on one end, or by using a "starter switch." If
your light is started with the switch, you hold the button down for a few
seconds, then release it. If you watch the bulb at the same time, you will
see the ends of the bulb start to glow, first very dimly, then brighter.
When you release the switch, you change the flow of the current from through
the filaments to through the bulb itself. The "starter" does this for you
automatically. The hand starting switch is lots cheaper to make than the
circuitry and the socket for the "starter." It also takes a lot less room in
the "hood" or reflector over your tank.
In a "rapid start ballast," a differently designed fluorescent bulb is used.
"Rapid Start" bulbs are designed to be started by Rapid Start Ballasts. In
these, a small current ALWAYS flows through the filaments. The inside of the
bulb - the amount of vacuum, the gases, etc. - is designed to start the arc
very very quickly, without much heating of the filaments. MOST "Pre-Heat"
bulbs WILL NOT START with magnetic rapid start ballasts. Some can be induced
to start by rubbing the bulb from end to end, thus capacitatively inducing
the arc. If you DO get a Pre-Heat bulb to work with a rapid start ballast,
the end or ends of the bulb will get really black really soon. This is
because the filaments always have a current going through them, something
that does not happen with the normal "pre-heat" ballast. Interestingly
enough, Rapid Start Fluorescent Bulbs work just fine with either the hand
start switch or the "starter." It just does not work the OTHER way! Rapid
Start ballasts are made in Magnetic, Electronic, or Hybrid kinds. They don't
look any different on the outside. The differences are INSIDE.
WHY THE ELECTRONIC BALLAST GIVES MORE LIGHT FOR THE SAME AMOUNT OF
Remember how the bulb flickers, up to maximum brightness, then almost to
zero, then up, then down, over and over? Well, the Electronic Ballast does
its wizardry and changes the 50 or 60 cycle alternating current into
(usually) 400 cycle alternating current. This (to make a very crude analogy)
keeps the bulb phosphor glowing at almost the peak brighness almost all of
the time. The current cycles back and forth, going up and down 800 times a
second, and the phosphor never has a chance to quit glowing like it did on
ordinary alternating current. Another advantage to the Electronic Ballast
is the fact that is wastes VERY little electricity as useless heat. The new
Electronic Ballasts we are installing here in the Aquarium Center draw
slightly over 60 watts of total energy. Yet, they light TWO, 40 watt bulbs,
and light them MUCH BRIGHTER than the Magnetic Ballasts they are replacing.
The Magnetic Ballasts draw more than a hundred watts of electicicy to light
two, 40 watt bulbs. They waste a LOT of electricity as heat. And, the bulbs
are not nearly as bright!!
During the Iowa State Fair, there is a severe voltage drop in our area. Too
many other exhibitors, all drawing electricity from under-sized main wiring.
Anyway, we sometimes have voltages UNDER 100 volts. Many Magnetic Ballasts
just quit then. The lights just dim, then go out. They cannot be re-started
until late at night, when all of the other current users close up shop and
turn off their lights. The Electronic Ballasts we are now using are very
cleverly designed, and give the same amount of light with line voltages from
a low of only 90 volts up to over 140 volts.
Why doesn't everybody use Electronic Ballasts? Probably because Magnetic
Ballasts are cheaper to make and install.
WHAT ABOUT HIGH OUTPUT AND VERY HIGH OUTPUT FLUORESCENT BULBS?
High Output bulbs and Very High Output Bulbs are just bulbs designed for much
higher current arcs. A 24 inch long, 40 watt High Output fluorescent bulb
needs the same amount of current as a 48 inch long standard fluorescent bulb.
Don't try to use a 40 watt magnetic ballast on a 24 inch, 40-watt High Output
bulb. It probably will not work. Some newer magnetic ballasts will work, not
as well as a proper ballast, but they will work. Sort of. At least some of
our old ballasts won't work at all with such bulbs. You turn on the light,
and exactly NOTHING happens. We found both "Hybrid" 40 watt Rapid Start
Ballasts and Electronic 40 watt Rapid Start Ballasts worked just fine with 24
inch long, 40 watt High Output bulbs. (I have a friend who is a Licensed
Professional Engineer, with a PHD in Electronic Engineering who told me to
try the Electronic Ballasts.) If you watch Electronic Ballasts as they are
starting bulbs, they seem to work really WIERD. They "pulse" current through
the filaments to start the bulbs, then turn off the filament current when the
bulbs start. You can see this happen if you only have the pins on one end of
the bulb connected to the ballast. The filaments at the ends of the bulb
glow bright then dim then bright and so on. (This can happen if you are using
those rubber "plug in" special aquarium end caps. You don't always get the
pins lined up just right.)
_Ice Cap Electronic Ballasts are very good ballasts._ My friend tells me it
is entirely possible to make an Electronic Ballast that can "sense" what kind
of bulb is connected to it, and automatically regulate the current in the arc
to the right level. I have never tried an Ice Cap, but I would guess they are
designed to operate that way.
Ordinary Electronic Ballasts are a LOT CHEAPER!!!! We are paying from #39.50
up to about $44.00 each for the Electronic Ballasts we are using. (That is
wholesale from Grainger.) There are Electronic Ballasts made for all sorts
of fluorescent bulbs. You can get them to light only one bulb. Or, light two
bulbs at once. Or, you can get them to light two or even three bulbs, each
bulb lighting all by itself. The advantage of that is, just because ONE bulb
"wears out," the others will keep on working all by themselves. You pretty
much get what you want, and are willing to pay for.
DO YOU REALLY GET ALL THAT MUCH MORE LIGHT FROM HIGH OUTPUT BULBS?
Sort of. There is no such thing as a free lunch!!! The bulbs are much
brighter, but they also draw much more electic current. The lighting
engineers say you want "the most Lumens per Watt," I would say "Most Bang for
the Buck." The bottom line seems to be you get pretty much the same Lumens
per Watt from ANY Electronic Ballast with ANY combination of bulbs. It takes
more bulbs with "standard" 40 watt bulbs, fewer bulbs with High Output and
Very High Output bulbs. The amount of electricity used per actual Lumen of
light output is just about the same, no matter which bulbs you use. We found
here that High Output Bulbs "leak" more Ultraviolet light, which actually
_burned_ some corals before we figured out what was happening. ALL Electronic
Ballasts are brighter than Magnetic Ballasts. As far as I know, there are no
exceptions to this rule.
Should you buy Ice Caps? Darned if I know! They sure seem expensive! My
Engineer friend thinks they are pretty "pricey." They work very well indeed,
and have some good safety features built in. They turn off automatically if
you have a dangerous current leakage. So does any properly installed Ground
Fault Interrupter. Tunze makes excellent stuff, so does Dupla. Expensive
stuff! Is it worth the money? Again, I simply do not know.
I hope the above VERY LONG post will be helpful.