Regardless of the style of cabin that
someone decides to build, the cabin will most likely
have to be wired for user comfort. The very best way
to go about wiring a cabin, would be to hire an
electrician who thoroughly knows all of the local
building codes and regulations. However, there are
some locations such as remote Alaska, where
electricians are not readily available, and it is
legal for homeowners to do their own wiring. Under
such conditions it is important for a homeowner to
gather information about electricity, and understand
building codes, before they wire their home.
There are two main types of electricity, both
AC (alternating current) and DC
(direct current). Most homes that are on the
grid have an AC wiring system, because city power
comes as alternating current. The amount of
electricity (potential) in in a given wire is
measured in volts, which is abbreviated as
V. For the typical home that is on the grid,
the power system is usually 120V because that is the
what most household appliances will run off of.
However, there are some appliances that require a
significant amount of power to run, such as shop
tools, ovens, and other equipment which is 240V.
Batteries are a common source of electricity,
and are often used in conjunction with solar
panels to power homes. However, batteries have
DC current, and since home appliances are AC, it is
necessary to include a sine wave converter in the
system in order to convert the power from DC to AC.
The amount of power in a battery is measured as
potential difference and the standard units of the
potential difference is volts (V).
According to Randall Knight in his text Physics
For Scientists and Engineers, there is a
simple relation between volts, resistance, and amps.
The relationship is I=V/R where I is the
current, and is measured in Amps (A), V is potential
difference, and is in units of Volts (V), and R is
resistance, and is in units of ohms. This
relationship is important when used to solve
circuits when wiring a house (or anything else).
Resistance is a very important concept of
electricity. Take for instance the incandescent
light bulb. The incandescent light bulb works
by reducing the size of wire that electricity has to
travel through, and the reduced size then causes the
electrons traveling through the wire to have lots of
collisions. Those collisions give off energy in the
form of useable light, and excess heat. These
collisions are a result of resistance. When wiring a
cabin, there are two common ways to wire electrical
fixtures, both in parallel, and in series. When
there are multiple resistors wired in series, they
can be replaced by a single equal resistor by the
equation Req =
R1 + R2
+...+Rn (Physics
for Scientists and Engineers P.899).
When there are multiple resistors in
parallel, they could be replaced by
a single resister by the equation Req
= {(1/R1)
+ (1/R2)+...+(1/Rn)}^-1(Physics
for Scientists and
Engineers P.903).
The key to
understanding
resistors in
series is that
they all have the
same amount of
current running
through them. The
current in
parallel resistors
on the other hand
has to split into
the different
paths, it is split
up according to
the junction law
which states that
Itotal
= I1
+ I2
+...+ In
(Physics
for Scientists and
Engineers P.903).
The following
example will show
the various steps
to analyzing and
solving a circuit
with both
parallel, and
series resistors.
Drawing and solution produced by the author.
As we can
see, we can replace the six resistors with one
equal resistor which has a resistance of 57.86
Ohms.
