Gas and Electrical Safety

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Gas and Electrical Safety
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Chemical/Physical Properties of Natural Gas

• Lighter than air
• Naturally odorless
• Mercaptan
• Odor Threshold
• Combustible limits
• Non-Poisonous
• Simple asphyxiant
• Oxygen deficiency
• 1000 Deg. F
• Air monitoring
• Required by OSHA

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Responding to Blowing Gas Emergencies

• Response scenarios
• Emergency Response Services
• Gas escaping outsidenot burning
• Gas Escaping outsideburning
• Gas escaping insidenot burning
• Gas escaping insideburning

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NorthWestern Energy Response
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• Then there is electricitythe demon, the angel,
  the mighty physical power, the all-pervading
  intelligence! Is it a factor have I dreamt
  itthat, by means of electricity, the world of
  matter has become a great nerve, vibrating
  thousands of miles in a breathless point of
  time?
• --Nathaniel Hawthorne
• The House of the Seven Gables, ch. 17

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What Is Electricity?

• Form of Energy
• Energy is Power
• Electricity
• Atoms
• Protons
• Neutrons
• Electrons
• Voltage
• Generator
• Electrical pressure
• Current

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Where Does Electricity Come From?

• Circuit
• Power Plant
• Power lines
• Transmission wires
• Substations
• Smaller power lines
• Transformers
• Service drops
• Meter box
• Wires inside walls
• Outlets and switches

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Electricity Travels Through Conductors

• Conductor
• Metals
• Copper
• Aluminum
• Water
• Your body
• Electricity travels at the speed of light
• 186,000 miles per second

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Insulators Keep Electricity Where it Belongs

• Insulators
• Glass
• Plastic
• Ceramic
• Break or disconnect
• Touch potential

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How Electricity Acts

• Think of electricity as water
• Reservoir? Pipes? Pump
• Generator? Electric Conductors? Pressure
  (Voltage) Generator
• Water Flow
• Water current
• Electricity Flow
• Electric current
• Voltage is the pressure causing the current
  (electrons) to move through the wire
• Measuring Water
• 10 gallons per second
• Measuring Electricity
• 25 amps

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How Electricity Acts
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Electrical Safety

• What are the hazards?
• 5th leading cause of death
• 5,348 deaths
• 411 deaths per year
• How can a worker be exposed or put at risk?
• Present at most jobsites
• Workers exposed to electrical energy daily
• Broken light bulb
• Overhead power lines

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How Electricity Affects the Body

• Amperage
• Amperage is the most destructive factor in
  electrical accidents.
• Electrical Injuries consist of four main types
• Electrocution (fatal)
• Electric shock
• Burns
• Falls caused as a result of contact with
  electrical energy
• For death to occur
• Body must become part of an active electrical
  circuit
• Extent of injuries
• Depends on the currents magnitude (amperage), the
  pathway of the current through the body, and the
  duration of current flow through the body

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How Electricity Affects the Body

• 5 Milliamps is the trip setting for GFCI
  protection
• 60 Milliamps is the current required to light a
  7.5-Watt light bulb
• 800 Milliamps is required to power a 100-Watt
  light bulb
• 8,000 Milliamps is required to power a 1,000-Watt
  hair dryer

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Electrical Injuries May Occur in Various Ways

• Direct contact
• Flash burns
• Flame Burns
• Falls from heights

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Effects of Contact to the Body

• High Voltage
• Small superficial injury
• Destroys subcutaneous tissues
• Internal blood vessels may clot
• Nerves in the contact area may be damaged
• Muscle contractions may cause skeletal fractures
• Temperatures in excess of 1800 degrees F
• Hot enough to vaporize skin instantly

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Accident Statistics

• 12 of all construction accidents
• 50 Heavy Equipment
• Distribution lines hit most frequently
• 90 involve overhead
• Why?
• Typically ground helper injured
• Moving/adjusting equipment

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Overhead Power Lines
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Mobile Equipment

• Limit of approach
• For every kV increase, increase the distance by
  0.4 inch

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Power Line Approach Guidelines

• Always observe Limit of Approach
• Use a signalman
• Consider all Power Lines as Live!
• Notify NWE when operating near a Power Line
• Keep personnel away from equipment when near the
  Limit of Approach
• Slow down
• Use warning devices
• Consider long spans and wind
• Dump trucks
• Excavation Equipment

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Always Call Before You Dig!

• Two business days before you dig.
• 1-800-424-5555

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If Contact Occurs
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If Contact Occurs
V1
Touch Potential
V2
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If Contact Occurs
Step Potential
V2
V3
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If Contact Occurs
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Other Options After Contact
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Other Considerations

• Reclosures

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Other Considerations

• Inductance

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Other Considerations
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Poles
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Remember

• Electricity will flow through conductive
  material.
• Never let any object within the Limit of
  Approach.
• When machinery touches power lines, all metal
  parts become electrified.
• If power lines break and fall onto communication
  wires, fences, or other metal objects, these also
  become energized.
• In an emergency, always assess the situation and
  dont panic and get tunnel vision.
• Be aware of the location and clearance of power
  lines at all times.
• ALWAYS treat power lines as if they are energized!

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