1 / 20

HVACR317 – Refrigeration

HVACR317 – Refrigeration. Safety and Hazard Prevention. Safety and Hazard Prevention. Current is the killing factor in electrical shock. The human body has resistance; if voltage is applied, current will flow through the human body.

oprah
Download Presentation

HVACR317 – Refrigeration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HVACR317 – Refrigeration Safety and Hazard Prevention

  2. Safety and Hazard Prevention • Current is the killing factor in electrical shock. • The human body 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.

  3. Diagram of Path of Electricity 1

  4. Diagram of Path of Electricity 2

  5. Diagram of Path of Electricity 3

  6. Effects of Current on the Body • A current of 2 to 3 mA (milliamps) will cause a tingling sensation. • Milliamps is 1/1000th of an amp. • The tingling sensation increases and becomes very painful at about 20 mA. • Currents between 20 – 30 mA will cause muscle contraction. • At this voltage, you may not even be able to release the wire you are holding.

  7. Effects of Current on the Body • Currents between 30 – 60 mA will cause muscle paralysis and difficulty breathing. • Currents at 100 – 200 mA will generally cause death.

  8. Lockout / Tagout Procedures • One of the best ways to prevent electric shock is to follow safety precautions such as Lockout/Tagout procedures. • Equipment that is being worked on should be disconnected from the power source and locked. • See the following slide for equipment used in the lockout/tagout procedure.

  9. Lockout / Tagout Materials

  10. Lockout / Tagout Procedures • The person working on the equipment should be the one to carry the only key. • This will prevent accidental activation of the equipment. • The power supply should be tagged with: • the name of the person working on it. • what service is being performed. • the reason for the service. • the date and time of the service.

  11. Basic Safety Tips • Never work alone. • Learn first aid. • Do not wear jewelry at work. • Be careful using screwdrivers on electrical panels.

  12. Tips Regarding Portable Electrical Tools • Electric tools with metal frames should have a grounding cord. • The grounding wire will protect the operator from electric shock by carrying the current to ground. • This lets the breaker or fuse trip the circuit. • NOTE: The grounding adapter must be connected to a ‘good’ ground.

  13. Example of Grounded Electric Tool

  14. Non-Conducting Ladders • Metal or aluminum ladders are conducting ladders; they can be hazardous when working near electricity. • Non-conducting ladders are those made of fiberglass or wood. • These will protect technicians from a shock to ground.

  15. The Safety Ground Wire • The equipment grounding wire is added for safety purposes; it is called the safety ground. • The safety ground is required by the National Electric Code (NEC) on all systems. • The color code for this wire is green or bare copper.

  16. The Safety Ground Wire • The safety ground (aka 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. • This provides an alternate pathway for electrons to go to ground and not through a technician.

  17. The Neutral Wire • The earth is always at zero potential (no voltage). • The earth can be used to complete an electrical circuit.

  18. The Neutral Wire • Many electrical devices operate with just one ‘hot’ wire and another one called neutral. • This is also known as “single-phase.” • A potential difference exists because the hot wire has voltage and polarity. • The “neutral” wire is connected to earth (grounded), which is zero voltage.

  19. 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 neutral wire has white insulation for ease of identification. • The neutral wire is connected to a solid copper rod (driven 8 feet into the ground). • The copper rod is called a “grounding electrode.”

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

More Related