1 HVACR317 – Core for Refrigeration Safety and Hazard Prevention

2  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  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

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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  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  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  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 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

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11 Safety and Hazard Prevention  The person working on the equipment should carry the only key  This will prevent accidental activation of the equipment  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 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 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 Portable Electric Tools  Electric tools with metal frames should have a grounding cord  The grounding wire will protect the operator from electrical shock

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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 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 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  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  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  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  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  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  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”  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  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