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In order
to ensure safety and proper operations within
an indoor garden, it is important to understand
the meaning of and logistics involved with electricity.
An electric
circuit is defined as a closed path
followed or
| Electric
circuit : A closed path followed
or capable of being followed by an electric
current. A configuration of electrically
or electromagnetically connected components
or devices. |
capable of
being followed by an electric current.
When an indoor lighting system is set up and
plugged in a current is relayed through the
chord via wall socket through the lamp and back
again where it is grounded.
The ballast ensures that the proper charge is
sent to your
| Grounded
: A large conducting body, such
as the earth or an electric circuit connected
to the earth, used as an arbitrary zero
of potential. A conducting object, such
as a wire, that is connected to such a
position of zero potential. |
lamp.
That is why it is so important to jive the wattages
of your ballast to your lamp. Too much power
will decrease the life of your lamp because
more power is reaching it than what it was designed
for. Too little power will not "fire"
your lamp.
The four
most basic units regarding electricity are voltage
(E), current
(I), power
(W), and resistance
| Resistance
: D etermines how much current
will flow through a component. Resistors
are used to control voltage and current
levels. A very high resistance allows
a small amount of current to flow. A very
low resistance allows a large amount of
current to flow. Resistance is measured
in ohms The opposition of a body or substance
to current passing through it, resulting
in a change of electrical energy into
heat or another form of energy. |
(R).
Voltage is a measure of
| Voltage
: is the difference in electrical
potential between two points in a circuit.
It's the push or pressure behind current
flow through a circuit, and is measured
in (V) volts. Household sockets are traditionally
run for 120 volts (normal outlet) or 240
volts (stove, washer/dryer, etc.) |
| Current
: Current is what flows on a wire
or conductor, like water flowing down a
river. Current flows from points of high
voltage to points of low voltage on the
surface of a conductor. Current is measured
in (A) amperes or amps. |
| Power
: The amount of current multiplied
by the voltage level at a given point measured
in wattage or watts. The product of applied
potential difference and current in a direct-current
circuit. |
energy
per unit charge between two points in the circuit
and is measured in volts. One may think of voltage
as the effective "pressure
|
difference"
which causes the current to flow. Current is the flow
rate of electric charge and is measured in amperes.
Power is measured
in watts
| Watts
: A measure of the amount of electricity
flowing through a wire |
, and resistance
in ohm's
| Ohms
: A unit of electrical resistance equal
to that of a conductor in which a current of one
ampere is produced by a potential of one volt
across its terminals. |
. A convenient
| Ampere
(AMP): this is the unit used to measure
strength of an electric current. |
analogy
to help
in understanding
the relationships
of these units
is
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a plumbing system. The voltage is equivalent
to the water pressure, the current is equivalent
to the flow rate, the power is the result of
the relationship between water pressure and
flow rate, and the resistance is the equivalent
to the relative size of the pipe. Because wall
sockets and established circuits do not vary
in regards to "pipe size" or circuit
size, our analogy will deal only with water
pressure, flow rate, and the corresponding water
"amount" or draw.The basic formula
to determine how our three units relate is called
Ohm's law formulated by Georg Simon Ohm (1787-1854)
and can be altered to solve for any variable
with knowledge of others:
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Let's
see how this relation applies to the plumbing
system. Let's say you have a tank of pressurized
water connected to a hose that you are using
to water the garden. What happens if you increase
the pressure in the tank? You probably can
guess that this makes more water come out
of the hose. The same is true of an electrical
system: Increasing the voltage will allow
more current flow. Now, take a hose and point
it at a waterwheel like the ones that were
used to turn grinding stones in watermills.
You can increase the power generated by the
waterwheel (power in watts) in two ways. If
you increase the pressure of the water coming
out of the hose (voltage), it hits the waterwheel
with a lot more force and the wheel turns
faster, generating more power. If you increase
the flow rate (current), the waterwheel turns
faster because of the weight of the extra
water hitting it.
The scenarios
above are not normally dealt with regarding
indoor lighting systems, but are good to help
understand the relationships involved in electricity.
This is because the voltage is wired in and
the amperage is an
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upper limit, with the wattage being the variable.
In other words, the grower should pay attention
not to exceed the upper limit of wattage and corresponding
amperage for the voltage they are wired for. In
a normal lighting system ballasts can be wired for
120 volts or 240 volts. Think of amps as cars going
through a tunnel- twice as many cars can travel
through a tunnel with two lanes as a tunnel with
one lane. Someone running one light system would
normally operate the unit under 120 volts because
this is what traditional home outlets are wired
for. The more electricity desired on a given circuit
the more voltage you will potentially need due to
the amount of amperage needed. If you have noticed
that washer/dryer and range plugs are configured
differently than your average home outlet that is
because these outlets are operating at 240 volts
due to
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the
higher amount of current needed to operate
these machines. As stated above, in an electrical
system, increasing either the current or the
voltage will result in higher power. However,
again, when dealing with indoor lighting it
is the wattage that is the variable being
altered. The grower needs to pay attention
not to exceed his amperage quota in order
not to trip a breaker or blow a fuse. Contact
a local electrician if you are unsure of your
specs.
Lets
look at an example, imagine you have a light
system with a 400-watt lamp operating on a
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120-volt circuit, whatwould your amperage (I)
be? You know that W = 400 W, and E
= 120 V. So you can rearrange the equation to solve
for I and substitute in the numbers:
I
= W/V = 400 W / 120 V = 3.333 amps
What
would happen if you use a 240-volt circuit and a
400-watt lamp?
400
W / 240 V = 1.667 amps
So
using a larger voltage reduces the amount of amperes
used and allows more wattage to be carried on the
same circuit. In other words, to allow the same
amount of power (400 watts) less current is used
(3.333 amps vs. 1.667 amps, respectively). This
will not save you money on your power bill (a watt
is a watt), but simply allow you to run higher amounts
of power on the same circuit.
HID
Lamps
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All
light bulbs operate off of reception of
a current and a corresponding emission based
on the pressure and presence of respective
gases or via a filament in incandescents.
We will be talking about HID and fluorescents
here.
The gases
inside HID
| HID
: High Intensity Discharge. |
and
fluorescent lamps are "excited" and
because of this release a measurable amount
of light energy as a measurable spectrum based
on the pressure the gas is being held under.
For
example, High Intensity Discharge (HID) lamps
normally elicit higher lumen
levels compared to
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fluorescents because HID's contain gas under a higher
level
| Lumen
: A lumen is the unit that expresses
the total quantity of light given of by a source
as seen by the human eye, regardless of direction.
A lumen is defined as the amount of light falling
on a surface of one square foot, every point
of which is one foot away from a source, (a
section of the inside surface of a sphere) of
one candlepower. A uniform source of one candlepower
placed in a sphere emits 12.57 lumens. |
of pressure.
Light in an HID lamp or a fluorescent is produced
by an arc discharge between two electrodes located
at opposite ends of an arc tube within the lamp.The
purpose of the ballast is to provide the proper starting
and operating voltage and current to initiate and
sustain this arc. The only difference between a Metal
Halide (MH) and High Pressure Sodium (HPS) ballast
is the presence of an igniter in the HPS ballast.
By the nature of the gas in a MH lamp, no ignition
charge is needed to create the arc and bridge the
gap between electrodes. By the nature of the gas in
an HPS lamp a split-second ignition charge is needed
to bridge this gap and "fire" the lamp.
This is why it is important to jive a MH lamp with
a MH ballast and an HPS lamp with an HPS ballast.
If a MH lamp is used with an HPS ballast the MH lamp
will be receiving an ignition charge that it is not
designed to withstand, significantly decreasing the
life of the bulb. If an HPS lamp is used in a MH ballast
the HPS lamp will not "fire" due to a lack
of an igniter. Refer to the "Lighting"
section under "Growers Guide" for further
info.
Recycle your
lamps: http://www.nema.org/lamprecycle/
(or lamprecycle.org)
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