Mr
Laing emailed a question.
He asked,
Since each side of 30 amp double breaker is 30 amps, is the total 60
amps?
The
answer is no.
The calculation shown above using Volts x Amps = Watts proves that amps
are not halved, or doubled, instead amps stay at 30 amps but
watts or power is doubled when using 240V.
The following explains why.
Generating electric power is accomplished many ways, but renewable
sources (wind, solar, batteries etc) must match the power generated by
traditional coal, atomic, and gas fired (thermal) power plants
and hydroelectric plants that use a rotating generator. Why? Because
the grid is currently engineered to deliver specific voltages at a
specific frequency, and end-user loads (light, motor, charge cord,
refrigerator etc) are manufactured to work with those same standard voltage and frequency of AC
power. Frequency is the number of generator rotations per second.
How a rotating
generator works: Passing a magnet, or electromagnet, over a conductive
material, for example a coil of copper wire, energizes the copper atoms
causing lighter weight electrons to come free from heavier weight
protons and start jumping from atom to atom and pushing more electrons
free in a cascade of electrons going down the wire. Add enough magnetic
force, and miles-long wire can be energized. The result is a
flow, or current, of electrons available to energize end user loads. Read more
 Volts x
amps = watts (or power)
Voltage is the force that pushes amperage (or current of electrons)
across the wire. Amperage represents the number of electrons.
Voltage generally remains stable throughout the day, but amperage rises
and falls, with more electrons flowing when more loads are turned on.
The breaker responds to heat caused by the flow of electrons ... too
many electrons on the wire, and it causes the wire to get hot, which
trips breaker. It's like having too many cars on the freeway, except
with electricity, the breaker trips. So each side of the 30 amp double
breaker will allow up to 30 amps. At no time does the breaker carry 60
amps, nor does the load receive 60 amps.
In a simplified version of events: As the power plant generator spins
around, the electromagnet inside the generator passes over coils of
wire, which causes electrons to start moving along the coil. One end of
each coil is connected to a transmission line that is energized by the
coil. The other ends of the coils are joined together to form the Neutral wire
that travels with transmission lines. The Neutral represents a midpoint
between coils.
The electrons reverse
direction every time the north and south poles of the electromagnet
pass over a coil,
creating the back-and-forth motion of
electrons found in AC power (alternating current). The back-n-forth of
electrons is called frequency, cycles, Hz or hertz, and represents the
number of rotations per second made by electromagnet. In US and
Americas, the frequency is standardized across the grid at 60 Hz, or 60
rotations per second, and likewise, end user products are rated for
that frequency.
The electromagnet
passes over each coil at a different moment so electrons on one coil
are moving different direction from electrons on another coil.
Since each coil is connected to a different transmission line, each
wire carries electrons that are going different directions from each
other. So when two wires are connected to a load, the
electrons flow back and forth, from one wire, then through the load,
going to the other wire, then electrons on both wires reverse direction
at same moment and flow back through the load again, rapidly changing direction at 60 times per
second. This is how power is delivered to a load.
A 30 amp double breaker is made for 240 volt. Each Hot wire in the 240
volt circuit originates from a different coil in the generator. When
both wires are connected a load that is rated for 30A 240V, then 30
amps worth of electrons will flow back and forth between each
wire. So both wires are working together to push and pull 30 amps worth
of electrons through the load, and this doubled effort is how the power
or wattage is
doubled in a 240V circuit, and also shows that amperage going through
load is 30 amp, not 60 amp.
If a single breaker is used, then the voltage is 120V, and amount of
power going to load is half of a 240V circuit. Why? 120V uses 1 Hot and
a Neutral, instead of 2 Hot wires. The 120V Hot wire comes from a coil
in generator, but Neutral comes from a midpoint between different
generator coils, and therefore carries 120V which is half of 240V. The
120V circuit delivers half power because 1 Hot and 1 Neutral are not
able to
push and pull electrons as hard as two Hot wires. |
