1. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts And Hazards Module II : Basic Electrical Concepts And Hazards 2-1

2. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards Describe basic electrical concepts that pertain to P/HEVs and EVs. Terminal Objective ● Define basic electrical terms. ● Understand the difference between electrical systems found in structures and those found in P/HEVs and EVs. ● Understand how electricity affects the body and how to protect against electric shock. Enabling Objectives 2-2 Module II Objectives

3. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards ● Electrical terms ● Types of electricity ● Understanding electrical circuits ● Building electrical systems vs. vehicle electrical systems ● Effects of electricity on the body 2-3 Module II Outline

4. Voltage: Electrical Potential Comparable to water pressure or PSI in a hose. 2-4 Basic Electrical Terms Measured in Volts.

5. Current: Quantity of electrons flowing Comparable to the rate of flow of water or gallons per minute (GPM). 2-5 Basic Electrical Terms Measured in Amperes.

6. Resistance: A material’s opposition to conducting current Comparable to friction loss in hose lines or appliances. 2-6 Basic Electrical Terms Measured in Ohms.

7. Hybrid Electric Vehicle DC Circuits Typically found in electronic devices that utilize battery power and some industrial applications. AC Circuits Found anywhere electricity is supplied by the utility company from the power grid, such as in buildings. 2-7

8. Alternating Current Current repeatedly reverses direction. Hybrid Electric Vehicle DIRECT CURRENT VS. ALTERNATING CURRENT Direct Current Current always flows in the same direction. 2-8

9. 2-9 Types of Electricity Found in P/HEVs and EVs DC ● Found in all P/HEVs and EVs. ● All use batteries for electrical storage. AC ● Found in some P/HEVs and EVs. ● These models use AC motors. ● DC is converted to AC.

10. 2-10 ● With both AC and DC, there must be a completed path, or circuit, for current to flow. ● A switch creates a break in the circuit when “OFF”. ● Turning the switch “ON” completes the circuit, allowing current to flow. ● Injury can occur when a person’s body becomes part of a circuit by completing a path for current. Understanding Electrical Circuits OFF ON

11. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards Video Electrical Circuits 2-11

12. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards Video Electrical Circuits 2-12

13. ● All HV circuits (AC or DC) are isolated from the vehicle chassis. ● Safeties will cause a vehicle HV system to shut down should chassis become part of the circuit. 2-13 HV POWER SOURCE ELECTRIC MOTOR Vehicle vs. Building Electrical Circuits

14. 2-14 ● Unlike in a structure, the earth is not part of the circuit design. ● Introducing a path to ground (touching or spraying water) will not, by itself, complete a circuit. Vehicle vs. Building Electrical Circuits ELECTRIC MOTOR ● To receive a shock, you must place your body in a position to become part of a circuit. HV POWER SOURCE

15. 2-15 ● Human body and PPE provide some resistance to electricity. How Electricity Affects the Body ● Voltage must be high enough to overcome resistance before it can enter your body. ● Environmental conditions, like being wet, can greatly reduce resistance.

16. 2-16 How Electricity Affects the Body ● Once resistance is overcome, Amperage usually determines degree of damage. ● Circuits in P/HEVs and EVs have both the voltage and amperage to be considered highly dangerous.

17. 2-17 ● 9V battery: Not enough voltage to overcome resistance of dry skin How Electricity Affects the Body Examples ● Stun Gun: High voltage, but not enough amps to do real damage.

18. 2-18 How Electricity Affects the Body Analogy ● A 2 PSI low pressure hose flowing at 3 GPM would not hurt if aimed at you. ● A 1000 PSI pressure washer, pushing the same 3 GPM could seriously harm you. ● The high pressure (voltage) allows the current to overcome your skin’s resistance.

19. OBSERVABLE EFFECT 240 70 40 Startle Reaction Can’t let go Electrical Burns Possible Ventricular Fibrillation Milliamps (1000 mA = 1 A) 2 2-19 DC Current Effect on Humans Some models of P/HEV and EV generate current in excess of 100 Amps, or 100,000 mA 1 2 Effect thresholds based on full grown adult physiology. Effects on smaller persons or children may occur at lower amperage. Personnel Protection Devices for Specific Applications, Electric Power Research Institute, Project 6850-02, Final Report, October 1999, prepared by Underwriters Laboratories Inc. 1 2

20. AC Current Effect on Humans OBSERVABLE EFFECT 833 105 70 20 6 6.5 Startle Reaction GFCI will trip Can’t let go Muscle Contraction (Respiratory Paralysis) Electrical Burns Ventricular Fibrillation 2-20 Current Used by a 100 Watt Light Bulb Milliamps (1000 mA = 1 A) 1 2 Effect thresholds based on full grown adult physiology. Effects on smaller persons or children may occur at lower amperage. Personnel Protection Devices for Specific Applications, Electric Power Research Institute, Project 6850-02, Final Report, October 1999, prepared by Underwriters Laboratories Inc. 1 2 Some models of P/HEV and EV generate current in excess of 100 Amps, or 100,000 mA

21. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards ? What is the difference between Voltage and Current? 2-21

22. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards Voltage is the electrical potential of a circuit, or the “pressure” of the current. Current is the rate of flow, measured in amperes or amps. 2-22 Answer

23. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards ? What are the two types of electricity used in P/HEVs and EVs? 2-23

24. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards Direct Current (DC) and Alternating Current (AC) 2-24 Answer

25. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards ? For current to flow (AC or DC), what must be completed? 2-25

26. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards A Circuit or path 2-26 Answer

27. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards ? What is a major difference between a HV electrical system in a car and those found in structures? 2-27

28. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards Vehicle HV Systems are isolated from the chassis, where structures’ electrical systems are grounded to the earth. 2-28 Answer

29. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards ? The risk of a shock occurs when the body becomes part of the_________? 2-29

30. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards Circuit 2-30 Answer

31. NFPA ELECTRIC VEHICLE SAFETY FOR EMERGENCY RESPONDERS Module II : Basic Electrical Concepts and Hazards ● Electrical Terms. ● Types of Electricity. ● Understanding Electrical Circuits. ● Building Electrical Systems vs. Vehicle Electrical Systems. ● How Electricity Affects the Body. 2-31 Module Summary