1. Electric Energy Measurement, Units, and cost Your Electric Bill
Cost to Operate Appliances

2. Topics Part 1: Your Electric Bill What Electric Energy is
How Electricity is Measured
Reading your Electric Bill
Part 2: Cost to Operate Appliances
Power – Energy - Cost
Reading Appliance name plates
Calculating the cost to operate appliances

3. Key Terms Voltage Current Resistance Load Power Energy Kilowatt
Kilowatt - Hour

4. Part 1: Your Electric Bill What is Electric Energy?
Energy helps us do many things.
Energy is defined as the ability to do work.
Electrical Energy is
Easily convertible to other forms
Easily moveable from one area to another
Not easily stored

5. Units of Measure Ohm’s Law: V=IR Power Law: P=IV Voltage Current
Resistance
Time Rate of Energy Usage
Power
Watts = Joule/s
Energy Used
Kilowatt-hours

6. How Electricity is Measured

7. Read both sets of dials and calculate the usage per day.

8. (41615 – 40565) / 5 = 1050 kWH / 5 days = 210 kWH/day

10. Part 2: Cost to Operate Appliances Power – Energy - Cost
Energy consumed: E = P t E =100 W bulb left on for 20 hours = 2 kWH
Cost to Operate: C = E R C = 2 kWH x $0.15 / kWH = $0.30

11. Reading Appliance Nameplates

12. Calculating the Cost to Operate an Appliance
Power consumed: P = I V A 120V appliance with 2 Amps of current uses 240 Watts of power.
Duty cycle:
The total number of hours that the appliance is on during a typical period of time (day, month, or year). 2 hour/day = 2 x 365 = 739 hr/yr
It is sometimes shown as a percentage 2 hour/day = 2 hour / 24 hours = 8% 739 hour/yr = 739 / 8760 = 8%
Energy Consumed: E = P t E = 240 W x 2 Hr/day = kWH/day
Cost to Operate: C = E R C = kWH x $0.15/kWH = $0.072 each day
Annualized Cost $0.072 /day x 365 day/yr = $26 / yr