HVACR317 – Core for Refrigeration

1. HVACR317 – Core for Refrigeration Safety and Hazard Prevention

2. Safety and Hazard Prevention • Current is the killing factor in electrical shock • Human bodies has resistance • If voltage is applied, current will flow through the human body • If one tenth of the current required to operate a 10 watt light bulb passed through your chest, the result could be lethal

6. Safety and Hazard Prevention • A current of 2 to 3 mA. • Will cause a tingling sensation • (The m stands for milli, A is for amps) • Milli is 1/1,000 of an amp

7. Safety and Hazard Prevention • The tingling sensation increases and becomes very painful at about 20mA • Currents between 20 and 30 mA will cause muscle contraction • At 20 and 30 mA you may be unable to let go of the wire

8. Safety and Hazard Prevention • Currents between 30 and 60 mA • Will cause muscle paralysis and difficulty breathing • Currents at 100 and 200 mA • Will generally cause death

9. Safety and Hazard Prevention Lockout – Tag Out Procedures • One of the best ways to prevent electrical shock • Equipment being worked on, should be disconnected from the power source and locked

11. Safety and Hazard Prevention • The person working on the equipment should carry the only key • This will prevent accidental activation of the equipment

12. Safety and Hazard Prevention The Power Supply Should Be Tagged With • Name of the person working on the equipment • What service is being preformed • Reason for service • Date and Time

13. Safety and Hazard Prevention Safety • Do not work alone • Learn first aid • Do not wear jewelry • Be careful using screwdrivers on electrical panels

14. Safety and Hazard Prevention Portable Electric Tools • Electric tools with metal frames should have a grounding cord • The grounding wire will protect the operator from electrical shock

17. Safety and Hazard Prevention Portable Electric Tools • The grounding wire will carry current to ground • This will let the breaker or fuse trip the circuit • The grounding adaptor must be connected to a good ground

18. Safety and Hazard Prevention Non – Conducting Ladders • Metal or aluminum ladders • Can be hazardous • Non – Conducting ladders are made of fiberglass or wood • Will protect you from a shock to ground

19. The Safety Ground Wire • The equipment grounding wire is added for safety purpose • It is called the safety ground • The safety ground is required by the National Electrical Code on all electrical systems • The color code for this wire is green or bare copper

20. The Safety Ground Wire • The safety ground (chassis ground) connects to the same terminal as the neutral wire at the service panel • The safety ground only carries current in the event of a short circuit • The safety ground wire is connected to the frame of a motor or appliance

21. The Safety Ground Wire • This will provide an alternate pathway for electrons to travel to ground and not through someone’s body

22. The Neutral Wire • The earth is always at zero potential (no voltage) • The earth can be used to complete an electrical circuit • Many electrical devices operate with just one hot wire and another wire called neutral

23. The Neutral Wire • This is also called single phase • A potential difference exists because the hot wire has voltage and polarity • The “neutral” wire is connected to the earth (Grounded) which is zero voltage

24. The Neutral Wire • The hot wire usually has black insulation • The hot wire can be another color except white or green for ease of identification

25. The Neutral Wire • The neutral wire has white insulation ease of identification • The neutral wire is connected to a solid copper rod (driven eight feet into the ground) • The copper rod is called a “grounding electrode”

26. The Neutral Wire • The grounded neutral wire has zero voltage • A zero volt reading will be found from the white wire to ground • A 120 volt reading will be found from the hot wire to neutral or ground