2. Principles of Electricity 6831.16

3. Volt The measurement of electrical pressure

4. Ampere The rate of flow of electricity

5. Watt The measurement of electrical power

6. W = V x A Watts equal volts multiplied by amps

7. W = V x A This formulas is sometimes called the West Virginia formula

8. W = V x A How many watts of electricity will a 7.5 ampere electric motor use in 5 hours on a 120 volt circuit W=120x7.5x5 W=4500

9. V = W/A Volts equal watts divided by amps

10. V = W/A What volt circuit is needed for an 7.5 amp electric motor that uses 900 watts in one hour V=900/7.5 V=120

11. A = W/V Amps equal watts divided by volts

12. A = W/V What should the amp rating of an electric motor be if it uses 900 watts of electricity in one hour in a 120 volt circuit A=900/120 A=7.5

13. Kilowatt 1000 watts

14. Cost of Electricity Cost per kilowatt x number of kilowatts x hours of use

15. Cost of Electricity If electricity costs 12 cents per kilowatt hour, how much would it cost to use 2 kilowatts per hour for 10 hours.12 x 2 x 10 = $2.40

16. I = E/R Ohm’s Law Amps (I) = Volts (E) divided by Resistance (R)

17. Circuit Breaker Protects circuits form overload of current by tripping to break or open the circuit

18. Circuit breaker

19. Fuse Protects circuits from overload by melting a metal strip in the fuse

20. Conductors Materials such as copper, aluminum, or water that will carry or conduct electricity

21. Insulators Materials such as rubber and plastic that will not conduct electricity

22. Hot Wire A current carrying conductor under electrical pressure

23. Neutral Wire A current carrying conductor not under electrical pressure (has volts)

24. Ground Wire A conducting wire that transmits current to the earth to minimize the danger of electrical shock

25. Formulas to Compute Electrical Energy and Cost

26. Organizations National Fire Protection Association (NFPA) promotes and improves the science and methods of fire protection and publishes the National Electric Code (NES)

27. Organizations Underwriter Laboratories (UL) tests all types of wiring materials and electrical devices for safety

28. Safety Precautions Wear boots or shoes with rubber heels to insulate against shock

29. Safety Precautions Wear clothing made of materials low in flammability to prevent fires

30. Safety Precautions Ground all outlets, switches, service entrances to prevent shock

31. Solderless wire nut

32. Safety Precautions Extension cords should not be used under carpet because of fire danger

33. Safety Precautions Extension cords should not be used under carpet because of fire danger

34. Safety Precautions Standing in water or damp places or touching switches or receptacles with wet hands may cause electrical shock because water conducts electricity

35. Safety Precautions Do not touch someone undergoing electrical shock because both people will become part of circuit, and both will be shocked

36. Safety Precautions Always turn circuit breaker to “off” position before beginning work

37. Safety Precautions Use correct size fuses and circuit breakers to prevent fires

38. Safety Precautions Use only double insulated portable tools or those with three wire grounded cords to prevent shock

39. Safety Precautions The two deadliest hazards associated with electricity are shock and fire

40. Safety Precautions Precautions and common sense should be used to prevent conditions that will cause either

41. Principles of Electricity 6831.16