Electrical Safety

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Electrical Safety
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Electrical Safety

• http//www.youtube.com/watch?vHr4fywrPqq0
• http//www.youtube.com/watch?vbX_ESSUlpYM
• http//www.youtube.com/watch?vGYbsnyA7yRY
• http//www.youtube.com/watch?vcedGEI4xeOo
• http//www.youtube.com/watch?vUkxStI9RC_YNR1
• http//www.youtube.com/watch?vCX_BhJjSEGc

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Electrocution

• Wall sockets are well within the death range
• Without warning
• No visible indicators
• Speed of Light
• Undetachable
• Immediate loss of control and consciousness

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Which of these is live?
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How wiring looks
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More wiring
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Which of these do NOT conduct electricity?

• Metal
• Glass
• Wood
• Water
• Rubber
• Plastic
• Cloth
• Rocks and Stones
• Air

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They all conduct electricity

• Because of salt and water vapor, which is always
  present
• http//www.youtube.com/watch?vy1YcNT-v2ik
• http//www.youtube.com/watch?vIgnebrbWKKw

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AC or DC? Low voltage or High?
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PC Power Supply

• Output 3.3V 27A, 5V 28A, 12V1 27A, 12V2 28A,
  -12V 0.6A, 5VSB 3A

If your body or body parts present
low-resistance opportunity, then the resulting
high current can kill you, by burn, open wound,
or cardiac arrest. A low-resistance opportunity
is moisture, salt, seat polyester,
metal, leather, etc.
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(No Transcript)
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Some simple rules

• Never work alone
• Colors, markings, and the word of others mean
  NOTHING
• Every wire is live
• Visually assess / dont believe the word of
  others
• Test with a meter if possible
• Unplug, switch off, disconnect
• Recognize hazards and REPORT THEM

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645 - 2222 Or 911
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• Why?

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Why?
?
Ungrounded case
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Grounded case
What is a GFI? are they safe?
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Ground Fault Interruptors

• GFIs operate by measuring the current balance
  between two conductors using a differential
  current transformer. The device will open its
  contacts when it detects a difference in current
  between the live conductor and the neutral
  conductor. The supply and return currents must
  sum to zero otherwise, there is a leakage of
  current to somewhere else (to earth/ground, or to
  another circuit, etc.).
• http//www.youtube.com/watch?vLGiYlyo2-eQ

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Ground Fault Interruptors

• A GFI will help to protect against electric shock
  where current flows through a person from a phase
  (live / line / hot) to earth. It cannot protect
  against electric shock where current flows
  through a person from phase to neutral or phase
  to phase, for example where a finger touches both
  live and neutral contacts in a light fitting a
  device can not differentiate between current flow
  through an intended load from flow through a
  person.