–          Your home is one large electric circuit that is wired in parallel (multiple electron paths)

–          Today we’re going to look at how electricity is delivered to your homes.

HOW ELECTRICITY FLOWS TO YOU

–          Electricity flows to every home through high-voltage wires.  The wires are either above ground and span over cities in hydro towers, or are wired underground (which is why you need to notify the electric company if you are digging on your property).

–          The highvoltage wires travel through a device called a transformer, which only allows 120V per wire to enter all households in North America.

–          Three wires enter each home from a hydro pole.  Two of these wires are “hot” or “live” (black) wires and one “neutral” (white) wire.  Having two wires entering the house and one leaving the house completes the circuit in your home.

ELECTRIC METER

–          The three wires that connect to each home are connected to the home by an electric meter.  The electric meter measures how much electrical energy is used in the home.

–          The three wires then travel from the electric meter to the main breaker switch.

MAIN BREAKER SWITCH

–          Every home has a main breaker switch that can turn off all the electrical energy traveling to the home.

–          When electricians work in a home, they turn the main breaker switch off so that they don’t electrocute themselves.

–          The main breaker switch is controlled by a device known as a circuit breaker.

DISTRIBUTION PANEL

–          The three wires now pass from the main breaker switch into the distribution panel.

–          The distribution panel is a metal box inside of each home that contains the circuit breakers or fuses for each circuit in the home.

–          There is one more wire in the distribution panel called the “ground wire.”  All electrical outlets in your home attach to the ground wire.  The ground wire is then dug deep into the ground so that it discharges any extra electricity into the Earth where it is harmless.

CIRCUIT BREAKERS

–          Instead of a fuse, newer distribution panels have circuit breakers to regulate the amount of electricity that goes through each circuit.

–          If too much current flows through the circuit breaker, pieces of metal heat up and separate.  When these metal pieces separate, the circuit is broken.

FUSES

–          Fuses are an older alternative to circuit breakers in a distribution panel.

–          Fuses are a piece of metal that allows for a complete circuit to exist.

–          If the amount of current flowing through the circuit is higher than is allowed by the fuse, the metal heats up and melts therefore breaking the circuit.

–          Fuses have a disadvantage over circuit breakers; once the fuse melts it needs to be replaced.  A circuit breaker can be reused.

WALL OUTLETS, POLARIZED PLUGS, AND GROUNDING PINS

–          Once electricity enters the home, it is safely divided into each room using wall outlets.

–          Wall outlets have the following safety features:

  • Wall outlets are made out of plastic, which does not conduct electricity.
  • Most wall outlets have room for a third prong.  This space is called the “ground terminal.”  The ground terminal is used in case of a short circuit; electricity will leave the home and travel to the ground outside.
  • Most wall outlets now have space for polarized plugs.  Polarized plugs have one prong that is larger than the other.  Using a polarized plug prevents the neutral wire from staying connected to the electrical device switch.  A polarized plug will only fit into the wall outlet one way.

–          The third prong of a plug is called the “grounding pin.”  This prevents a short circuit and makes sure the electricity passes to the ground rather through you.

GROUND FAULT CIRCUIT INTERRUPTER (GFCI)

–          This is a special type of wall outlet that contains a circuit breaker.  The GFCI outlet detects small changes in electrical current and breaks the circuit when too much current enters the circuit.

–          The GFCI is important to have in areas close to running water (kitchens and bathrooms) to make sure electricity stops when the current changes slightly.

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