Contributed by: Flowerman
Images archived 07-19-2003 Ballast
One of the best ways to save a bundle
on equipment is to wire up your own lights from a kit.
By buying the parts unassembled, you can probably
construct a light for half of what it would cost "ready
made" from a hydro shop. As well as saving money, you
can avoid the paranoia involved in shopping there. Many
people might be reluctant to work with wires and
electricity, which is certainly understandable, But it
isn't nearly as difficult as you might think.
Let's examine what is inside a ballast. There
really isn't much depending on which type of light you
buy. An high pressure sodium (HPS) ballast consists of 3
parts: The transformer, the capacitor, and the ignitor.
A metal halide (MH) ballast generally has just the
transformer and capacitor.
Every single one of
these parts is available at pretty much any lighting or
electrical supply warehouse, including the bulb and
socket. Break out the phone book and look in the yellow
pages under "lighting". Call them and ask if they carry
"Transformer, capacitor, ignitor (if for HPS), and
socket" for whatever size bulb you wish to use (150,
400, 1000 etc.) and type (Metal halide or High pressure
sodium) light you wish to purchase. Odds are, they will
have it. If not, try another store until you find the
one which has what you want. You can also order this
stuff from many online electrical supply places. There
is virtually no worry about having this stuff shipped to
your house, since it did not come from a "high profile"
When you purchase your ballast
components, be sure to buy the correct line voltage
rating you intend to operate it on. Most homes in the US
are wired for 120 volts. If your house happens to have a
different voltage (IE: 210) then you need the
corresponding ballast parts.
Another option is
to purchase what is known as a "multi-tap" ballast. This
type of ballast has a wire connection which can be
changed to allow several optional voltages. Some stores
may only carry multi-tap ballasts to save money on
inventory. A multi-tap ballast will work fine in any
situation. Multi-tap ballasts usually have the following
options inside: 120/208/240 and 277 volts.
Besides the transformer, ignitor, capacitor,
bulb and socket, you are going to also need the
following: About 20 feet of 14(or better) gauge wire, a
male plug set, about 8 wire nuts.
The wire and
the plug are for installing the power cord and socket to
your ballast. You can also simply buy a long heavy duty
extension cord, which you then will cut up. Whatever
wire you buy, make sure it is rated to at least 15 amps
and 1500 watts (14 gauge). That size is good for wiring
all the way up to 1000W lights.
Now, when you
get your parts, you will also likely get a wiring
diagram. It may come on a separate sheet of paper, but
more than likely it will be on a label on the
I have added a few descriptions for the
sake of clarity, but the basic schematic is the same.
This is for a HPS lamp and describes the wiring for the
3 internal components and socket. For some people, the
schematic may be a little confusing. Let's take a look
at the same thing but in a real time" photograph,
instead of the diagram.
You can clearly see all of the
components you will be dealing with and how they will be
wired together. Let's examine some of the more important
If you look at the transformer, you can
see it is labeled as having a "short side" and a "Long
side". These are my descriptions for the two different
areas of the transformer. If you look carefully you will
see that the transformer has two protuberances where
wires come out. One of them is thicker than the other.
That is the "long side". It is important to know the
difference when youre wiring it. The capacitor is a
simple affair with just 2 wires.
The ignitor has
3 wires. Look closely at the wires running from the
socket. You can see that each of them comes to a
junction with two other wires. All 3 wires at a
junction(and at all junction points for all wires) are
held together using a "wire nut". This is just a plastic
cap which screws onto wires to hold them together. Make
all the wire connections using wire nuts, do not use
Although you can't see it, all wires have
something printed on them so you can identify them. It
is going to be something numerical("X1","120") or
alphabetical ("lamp", "com"). In my example, wires are
noted with X1 or X2 or X3, other ballast kits may have
wires which simply say "one" or "Two" and
"volts"(instead of "120"). Sometimes wires are colored (
the ignitor wires in my example are red blue and white)
sometimes not. When wiring a ballast, don't get mislead
by the color of wires on the ignitor, capacitor or
transformer. These wires are connected according to what
is written on them, not by color. Color will only come
into play when dealing with wires coming from your power
cord and socket. These are going to simply be black,
white and green with no labeling. High
Pressure Sodium (HPS)
This wiring description is
for an advance brand ballast. If you end up with a
different brand and the wiring doesn't seem quite the
same, then it isn't. But should not be very difficult to
figure out the difference after familiarizing yourself
with the various wires and parts in the illustrations.
First, orient the transformer so that you know
which side is "long" and which is "short". Locate the 2
wires that say "cap" on them. They should be coming from
the inside of the transformer bulges. These wires all
either get connected directly to the capacitor using
connectors or by soldering, or with wire nuts to the
wires coming from the capacitor.
the wire coming from the long side of the transformer
which is labeled somewhere with the number 3(or "X3").
Then with a wire nut, connect it to the number 3 wire
coming from the ignitor. Make sure the nut goes down
snugly and that no bare wire can be seen.
going any further, you need to figure out how far from
the ballast the bulb will be placed. In my example, the
wires to the socket are only a foot long so that I could
get it in the picture. In real life, the wires will
usually be 6 to 10 feet long. Use a piece of heavy duty
(extension cord) wire and wire nuts to extend the
socket's wires as far as you need to. Just attach black
to black, and white to white. The green wire is a ground
which will get attached to your reflector on one end,
and to the transformer base/ballast box on the other end
to safeguard against shock.
Then, find the white
wire labeled "com X2" (or "com2" or whatever it is in
your particular case) coming from the transformer's
short side, the #2 wire from the ignitor (it may also
say "com X2" or "com2" or simply "2"), and the white
wire from the socket. Connect all three of these wires
together using a wire nut. Make sure the connection is
tight with no bare wire showing.
Find the wire
coming from the transformer's long side labeled "lamp".
Along with the #1 ("X1" or "1") wire from the ignitor
and the black wire from the socket. As above, connect
all 3 wires together with a wire nut.
almost done! The last two wires should come from the
transformer's short side. One should say "com" and the
other "120". These are the two wires that will go to
your power cord. Cut the extension cord to the right
size and trim away the outer insulation to expose the
three wires (white, black and green).
wire gets connected to the "com" wire on the
transformer, while the black wire goes with the "120"
(or whichever voltage you have) on the transformer. The
green wire is the ground and that gets attached to
either the ballast box or the base of the transformer to
safeguard against shock.
If you bought a
multi-tap ballast, now is the time to deal with that.
There should be a wire with a connector clip on it
attached to 1 of 4 possible spots on the transformer.
These 4 options are for 4 different voltages. Find the
one labeled "120" (or whatever your voltage is) and
attach the wire/clip to that one. Some ballasts simply
have a few extra wires inside labeled for different
voltages. In that case, find the one for your voltage
and strip the insulation off the end, then connect it
with a wire nut to the black from the power cord. Make
sure to leave the other voltage wires with all their
insulation. For safety's sake, cover each of the unused
wires (individually) using a spare wire nut for each one
to insulate them. Metal Halide (MH)
If you want a metal halide light, your task is even
easier because now you only have the transformer and
capacitor to work with and no ignitor. This is for
standard metal halide ballasts. On occasion, you run
into a MH ballast which has an ignitor. Try not to get
this kind if you can. If this is the only option, then
follow the instructions for HPS ballasts.
Connect the wire labeled "cap" coming from the
transformer's long side to the capacitor. Connect the
other wire coming from the capacitor (labeled "lamp") to
the black socket wire.
The transformers short
side will either have 1 or 2 wires coming from it
labeled "com". If there is only one, then connect that
wire with both the socket's white wire and the power
cord's white wire. If there are 2 "com" wires, then pick
one and connect it to the socket's white wire. Then
connect the other "com" wire to the power cord's white
wire. Connect the power cord's black wire to the
transformer's short side wire labeled "volts" or
"120"(or whatever voltage you have).
Now, even though it will
work without it (and even though it got left out of all
the illustrations), I recommend grounding the socket and
power cords. The grounds are the green wires coming from
these 2 cords. Both of these wires should be attached
either to the metal base of the transformer or to the
inside of the ballast box if it is made of metal. The
other end of the socket ground gets attached to the
metal part of the reflector. Double check everything.
Screw the bulb in the socket, then plug in the power
cord. The ballast should hum and the bulb should come on
almost immediately. If it doesn't or if you see or hear
anything unusual, unplug it.
Most likely, if you
made a mistake, then the bulb simply will not light.
Always wait five to ten minutes before touching any of
the wires after unplugging the unit. This is because the
capacitor holds electricity and you may get shocked if
you touch the wrong wire. Double check everything again.
A quick word about the bulbs. While all HPS
bulbs can burn in any position, a MH bulb must be
purchased specific to the mounting position you intend
to use. There are MH bulbs made specifically for
horizontal placement, base-up placement, vertical (base
down) placement and also universal placement. The
universal type bulbs can burn in any position, but are
not quite as bright (maybe 5% less) as the position