Unit 2: Electricity Lesson 8: Household Electricity

By the end of the lesson you should be able to:  Explain the difference between AC and DC  Describe the difference between breakers and fuses  Label the wires in plugs and outlets  Read electrical meters and Energuide labels  Describe how 3-way switches work

Direct Current (DC):  Electrons flow from negative to positive only  Produced by dry cells Alternating Current (AC):  Electrons flow one way and then the polarity reverses  Used in houses and industry  Switches 60 times per second (60 Hz)

Breakers:  Made of bi-metallic strip that bend at different temps and causes the circuit to break  Found in thermostats, breaker panels  Can be reset and reused – but only after the problem is fixed! Fuses:  A wire inside a case that will melt with too much current  Found in stoves, cars, radios  Cannot be reset, must be replaced  Typically 15 A or 20 A

 3 wires enter your house: 1. One 120 V wire 2. Another 120 V wire 3. A ground wire  1 and 2 are called “hot wires”  The ground is neutral  All 3 wires must pass through the electrical meter on the outside of your house  All circuits are in parallel…why?

 Large prong = neutral, returns electrons  Smaller prong = hot, source of electrons  Round bottom = ground, connects to ground rod

 Occur when one side of the plug/outlet is smaller/wider than the other  Used so the switch can be on the hot wire so when its off there no voltage difference between the terminals so there is less chance of electrocution

 A path of little resistance so current will increase and trip the breaker  Connects an appliance to the ground via the appliance case

 Used to measure energy used in your home  The more energy you use the faster the dials turn

 The dials are interlocking so they spin in opposite directions  When an arrow is between two numbers always choose the lower one  Practice reading meters on the worksheet

1. Energy consumed per year 2. This model as it compares to other makes and models in this class 3. Range of energy usage of other makes and models in this class 4. Types and range of similar models

 We add resistors to household circuits by plugging them in!  Resistors slow electrons down so there is less heat  Less heat = less chance of a fire!  Normal voltage is 120 V  Heavy duty voltage is 240 V

 Used in staircases so we can control the lights at the top and bottom of the stairs