Download Home Electric Wiring

HOME ELECTRIC WIRING
Lesson 13
HOME ELECTRIC WIRING

Most Homes in Ontario are connected to a
Power Transmission Grid. The grid is a huge
circuit. It covers hundreds of kilometres. The grid
connects each building to a power source. The
power station is the source of electric energy.

Electric wires carry current to each building
through a central electric panel. A number of
separate circuits carry current from the central
electric panel to different parts of the home. The
arrangement of circuits in a building is often
called the wiring.

Each circuit in the house is designed to handle a
certain number of loads safely. Special circuits
may also be designed for certain kinds of loads.
Only qualified electricians should ever try to
change wiring in a home.
Question: Think about the series and parallel
circuits you have built
 What will happen in your home if you connect too
many electrical devices in parallel in the same
circuit?

The circuit breaker will cut off power to avoid the
chance of a fire.
KNOW YOUR VOLTAGE

In North America, most household electric
circuits carry 120 V. However, different electrical
devices operate at different voltages
120 V
A regular
household electric
current is connected
to a 120 V circuit
Some household outlets
are connected to a
240V circuit.

It is very important to make sure each device is
plugged in at its correct voltage. If the voltage is
too low, the device will not work. If the voltage
is too high, the device will be damaged. The
circuit inside the device may even explode. This
can hurt people or start a fire.

Some Large appliances work at 240 V. Electric
stoves, freezers, and clothes dryers are examples
of appliances that may need 240 V. These
appliances have special outlets. A regular electric
plug will not fit into a 240 V outlet.

Many devices operate at less than 120 V. A
device that operates at 12 V cannot be plugged
directly into a regular 120 V outlet. Instead, the
plug carries current through a transformer. The
transformer reduces the voltage to 12 V.
QUESTION

When will an electric device require a
transformer?


When the voltage is too high
Why are 240 V outlets shaped differently from
120 V outlets?

To prevent 120 v appliances from being damaged
KNOW YOUR CURRENT

Every electrical device needs a certain amount of
electric current. Different kinds of devices use, or
draw, different amounts of current. Appliances
that convert electricity to heat usually draw more
current than other kinds of appliances.

Remember, when loads are added in parallel, the
total current in the circuit increases. The same
thing happens when you connect more devices to
an electric circuit by adding up the current draw
by each device.

Example: An electric kettle draws about 8 A. A
clock radio draws about 1 A. If you connect both
of these appliances in one parallel circuit, the
total current in the circuit is 8 A + 1 A = 9 A.
Kettle 8 A
Clock radio 1 A

An electrician planning a home electric system
must think about what kinds of appliances will
be used in the home. The electrician must also
think about where these appliances will be used.
Each circuit must be designed to carry the right
amount of current for its intended use.

What is the total current in this circuit?
3A

3A + 3A + 3A + 3A = 12 A
3A
3A
3A
DRAW A CIRCUIT FOR EACH SITUATION.

Draw an A.C. power source with one 3A bulb in
parallel with one 6 A bulb.


What is the total current draw in the circuit?
DRAW A CIRCUIT FOR EACH SITUATION.

Draw an A.C. power source with one 3A bulb in
parallel with one 4A bulb and one 5A bulb.


What is the total current draw in the circuit?