ELECTRICAL HAZARDS

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ELECTRICAL HAZARDS
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ELECTRICAL HAZARDS

• SHOCK. Electric shock occurs when the human body
  becomes part of the path through which current
  flows.
• The direct result can be electrocution.
• The indirect result can be injury resulting from
  a fall or movement into machinery because of a
  shock

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ELECTRICAL HAZARDS

• BURNS. Burns can result when a person touches
  electrical wiring or equipment that is energized.
• ARC-BLAST. Arc-blasts occur from high- amperage
  currents arcing through the air. This can be
  caused by accidental contact with energized
  components or equipment failure.

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ELECTRICAL HAZARDS

• ARC-BLAST. The three primary hazards associated
  with an arc-blast are
• Thermal radiation.
• Pressure Wave.
• Projectiles.

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ELECTRICAL HAZARDS

• EXPLOSIONS. Explosions occur when electricity
  provides a source of ignition for an explosive
  mixture in the atmosphere.

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ELECTRICAL HAZARDS

• FIRES. Electricity is one of the most common
  causes of fires both in the home and in the
  workplace. Defective or misused electrical
  equipment is a major cause.

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EFFECTS ON THE HUMAN BODY

• Depends on
• Current and Voltage
• Resistance
• Path through body
• Duration of shock

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Effects of AC Electricity

• More than 3 mA- Painful shock- cause indirect
  accident
• More than 10 mA- Muscle contraction No Let Go
  danger
• More than 30 mA- Lung paralysis, usually
  temporary

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Effects of AC Electricity

• More than 50 mA- Ventricular fibrillation,
  usually fatal
• 100 mA to 4 A- Certain ventricular fibrillation,
  fatal
• Over 4 A- Heart paralysis, severe burns

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1910.303(b)Examination of equipment

• Electrical equipment must be free of recognized
  hazards that are likely to cause death or serious
  physical harm to employees.

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1910.303(b)Examination of equipment

• Safety of equipment must be determined using the
  following considerations
• Suitability for installation and use
• Mechanical strength and durability
• Electrical insulation
• Heating effects under conditions of use

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1910.303(b)Examination of equipment

• Safety of equipment must be determined using the
  following considerations
• Arcing effects
• Classification by type, size, voltage, current
  capacity and specific use
• Other factors

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1910.303(c)Splices

• Conductors must be spliced with
• Splicing devices suitable for the use
• Brazing, welding or soldering (with a
  mechanically and electrically secure joint before
  soldering then soldered)

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1910.303(c)Splices

• All splices and joints and the free ends of
  conductors must be covered with an insulation
  equivalent to that of the conductors or with an
  insulating device suitable for the purpose.

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1910.303(e)Marking

• Electrical equipment may not be used unless the
  manufacturers name, trademark or other
  identification is on the equipment.

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1910.303(e)Marking

• Other markings must be provided giving voltage,
  current, wattage, or other ratings as necessary.
• Markings must be durable enough to withstand the
  environment.

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1910.303(f)Identification

• Each disconnecting means must be legibly marked
  to indicate its purpose, unless located and
  arranged so that its purpose is evident.

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1910.303(f)Identification

• These markings must be durable enough to
  withstand their environment.

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1910.303(g)(1)600 volts, nominal, or less

• Working space about electrical equipment.
• This section refers to a person qualified to work
  on electrical equipment, usually an electrician.

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1910.303(g)(1)(i)Working clearances

• Except as required or permitted, the dimension of
  the working space in front of live parts
  (operating at 600 volts or less) and likely to
  require examination, adjustment, servicing, or
  maintenance must be at least three feet.(See
  table S-1).

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1910.303(g)(1)(i)Working clearances

• The workspace in front of electrical equipment
  must not be less than 30 inches wide.

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1910.303(g)(1)(ii)Working clearances

• Working spaces required for this standard may not
  be used for storage.

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1910.303(g)(2)600 Volts or less

• Guarding of live parts operating at 50 Volts or
  more.
• The purpose of this requirement is to protect
  any person who is in the vicinity of electrical
  equipment against accidental contact, not just
  electricians.

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1910.303(g)(2)600 Volts or less

• Guarding of live parts.
• Guard against accidental contact by
• Location accessible only to qualified persons
• Permanent, substantial partitions or screens

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1910.303(g)(2)600 Volts or less

• Guarding of live parts.
• Guard against accidental contact by
• (C) Location on a suitable elevated balcony or
  platform
• (D) Elevation of 8 feet or more above the floor
  or other working surface

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1910.303(g)(2)600 Volts or less

• Guardian of live parts.
• In locations where electrical equipment would be
  exposed to physical damage, enclosures or
  guardians must be so arranged and of such
  strength as to prevent such damage.

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1910.303(h)(3)Over 600 Volts

• Workspace around equipment.
• Sufficient space must be provided and maintained
  around electrical equipment to permit ready and
  safe operation and maintenance.

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1910.303(h)(3)(ii)Illumination (Over 600 Volts)

• Adequate illumination must be provided for all
  working spaces around electrical equipment.
• The lights and switches must be arranged so that
  persons making repairs or turning on lights wont
  contact live ports.

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1910.303(h)(3)(iii)Elevation of unguarded live
parts

• Unguarded live parts above working space must be
  maintained at elevations not less than specified
  in Table S-3.
• The minimum is 8 feet.

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1910.304(a) Grounded and grounding conductors

• Identification of conductors.
• The grounded conductor is an energized circuit
  conductor that is connected to earth through the
  system ground. It is commonly referred to as the
  neutral.

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1910.304(a) Grounded and grounding conductors

• Identification of conductors.
• The equipment grounding conductor is not an
  energized conductor under normal conditions. It
  is energized only if there is a leak or fault in
  the normal current path and directs current back
  to the source.

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1910.304(a) Grounded and grounding conductors

• Identification of conductors.
• The National Electric Code requires that
• The grounded conductor (neutral) be continuous
  white or natural gray.
• The equipment grounding conductor be green, green
  with yellow stripes or bare.

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1910.304(a)(2)Polarity of connections

• No grounded conductor may be attached to any
  terminal or lead so as to reverse designated
  polarity.

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1910.304(a)(2)Polarity of connections

• Reversed polarity is a condition when neutral
  conductor is incorrectly connected to the hot
  terminal of a plug, receptacle or other connector.

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1910.304(e)Overcurrent protection

• 600 volts or less.
• (i) Conductors and equipment must be protected
  from overcurrent.

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1910.304(e)Overcurrent protection

• 600 volts or less.
• Fuses and circuit breakers are designed to
  disconnect a circuit from its supply source when
  a maximum allowable heat is reached.

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1910.304(e)Overcurrent protection

• 600 volts or less
• (iv) Location. Overcurrent devices must be
  readily accessible but not located where they
  will be exposed to physical damage or in the
  vicinity of easily ignitable material.

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1910.304(f)Grounding

• (4) Grounding path.
• The path to ground from circuits, equipment, and
  enclosures must be permanent and continuous

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1910.304(f)Grounding

• (5)(v) Tools likely to be used in wet and
  conductive locations need not be grounded if
  supplied through an isolating transformer with an
  ungrounded secondary of not over 50 volts.

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1910.304(f)Grounding

• (5)(v) Listed or labeled portable tools and
  appliances protected by an approved system of
  double insulation, or its equivalent, need not be
  grounded. However, they must be distinctively
  marked.

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Electrical ToolsDouble Insulated

• They work with GFCIs
• Casing must be labeled
• Tool must be inspected
• Extension cord must be three-prong

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1910.305(a)Wiring methods.

• General requirements.
• (ii) No wiring system of any type shall be in
  ducts used to transport dust, loose stock or
  flammable vapors, or used for vapor removal or
  ventilation of commercial-type cooking equipment.

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1910.305(a)Wiring methods.

• (2) Temporary wiring.
• Temporary electrical power and lighting wiring
  may be of a class less than would be required for
  a permanent installation.

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1910.305(a)Wiring methods.

• (2) Temporary wiring.
• Uses permitted, 600 volts or less.
• (A) During and for remodeling, maintenance
  repair, or demolition or similar activities.

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1910.305(a)Wiring methods.

• Uses permitted, 600 volts or less.
• (B) For experimental or developmental work
• (C) For a period not to exceed 90 days for
  Christmas decorative lighting, carnivals, and
  similar purposes.

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1910.305(a)Wiring methods.

• (2) Temporary wiring.
• Uses permitted, over 600 volts.
• Only during tests, experiments and emergencies.

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1910.305(a)Wiring methods.

• (F) Lamps for general illumination must be
  protected from accidental contact or breakage.
• Protection can be provided by an elevation of 7
  feet or by a suitable fixture with a guard.

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1910.305(a)Wiring methods.

• (G) Flexible cords and cables must be protected
  from accidental damage.Sharp corners or
  projections must be avoided.
• Protection must be provided when passing through
  doorways or other pinch points.

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1910.305(b)(1)Conductors entering boxes,
cabinets, or fittings.

• Conductors entering boxes, cabinets, or fittings
  must be protected from abrasion.
• Unused openings in cabinets, boxes, and fittings
  must be effectively closed.

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1910.305(b)(2)Electrical box covers

• All pull boxes, junction boxes, and fittings must
  be provided with approved covers.
• Metal covers must be grounded.

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1910.305(b)(2)Electrical box covers

• Outlet boxes must have a cover or a faceplate.
• Outlet box covers with holes for flexible cords
  must bushings or smooth, well- rounded surfaces.

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1910.305(d)Switchboards and panelboards.

• Panelboards must be mounted in approved cabinets
  or boxes and must be dead front.
• Others are accessible only to qualified persons.

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1910.305(g)(1)(i)Flexible cords and cables.

• Allowed uses
• Pendants
• Wiring fixtures
• Portable lamps or appliances
• Elevator cables
• Wiring cranes or hoists

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1910.305(g)(1)(i)Flexible cords and cables.

• Allowed uses
• Connect stationary equipment to facilitate
  frequent interchange
• Prevent transmission of noise or vibration
• For removal for maintenance/repair

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1910.305(g)(1)(iii)Flexible cords and cables.

• May not be used
• As a substitute for the fixed wiring of a
  structure.
• Where run through holes in walls, ceilings or
  floors.

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1910.305(g)(1)(iii)Flexible cords and cables.

• May not be used
• Where run through doorways, windows, or similar
  openings
• Where attached to building surfaces
• Where concealed behind building walls, ceilings,
  or floors.

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1910.305(g)(2)Flexible cords and cables.

• (ii) Flexible cords must be used only in
  continuous lengths without splice or tap.

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1910.305(g)(2)Flexible cords and cables.

• (ii) Hard service flex cords, No. 12 or larger,
  may be repaired if spliced so that the splice
  retains the insulation, outer sheath properties,
  and usage characteristics of the original cord.

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1910.305(g)(2)Flexible cords and cables.

• (iii) Flexible cords must be connected to devices
  and fittings so that strain relief is provided
  which will prevent pull off from being directly
  transmitted to joints or terminal screws.

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1910.305(j)Equipment for general use.

• (2)(ii) A receptacle installed in a wet or damp
  location must be suitable for the location.

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1910.307Hazardous (classified) locations.

• (b) Electrical installations.
• Equipment, wiring, and installations of equipment
  in hazardous (classified) locations must be
  intrinsically safe, approved for the location, or
  safe for the location.

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Hazardous LocationsClass I locations

• Locations in which flammable gasses or vapors are
  or may be present in the air in quantities
  sufficient to produce explosive or ignitable
  mixtures.

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Hazardous LocationsClass I, Division 1

• Location in which hazardous concentrations of
  flammable gases or vapors may exist
• Under normal operating conditions
• Because of repair or maintenance operations or
  leakage
• Because of breakdown or faulty operation

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Hazardous LocationsClass I, Division 2

• Location in which flammable gases or vapors are
• Normally confined within closed containers or
  systems
• Normally kept below hazardous concentrations by
  ventilation
• Normally kept below hazardous concentrations by
  positive-pressure ventilation (adjacent to
  Division 1)

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Hazardous LocationsClass II Locations

• Locations which are hazardous because of the
  presence of combustible dust.

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Hazardous LocationsClass II, Division 1

• Location where combustible dust may be present
  due to
• Normal operations
• Mechanical failure or abnormal operation of
  machinery or equipment
• combustible dust of an electrically conductive
  nature may be present.

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Hazardous LocationsClass II, Division 2

• Location where
• Combustible dust will not normally be in
  suspension in ignitable quantities
• Dusts may be in suspension as a result of an
  infrequent malfunction of handling or processing
  equipment.

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Hazardous LocationsClass III Locations

• Locations that are hazardous because of the
  presence of easily ignitable fibers or flyings
  but in which such fibers or flyings are not
  likely to be in suspension in the air in
  quantities sufficient to produce ignitable
  mixtures.

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Hazardous LocationsClass III, Division 1

• Locations in which easily ignitable fibers or
  materials producing combustible flyings are
  handled, manufactured or used.

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Hazardous LocationsClass III, Division 2

• Location in which easily ignitable fibers are
  stored or handled, except in the process of
  manufacture.

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1910.331 - .335Electrical Safe Work Practices

• Covers work practices rather than electrical
  equipment and installations.
• This should be a part of your Lockout/Tagout
  program

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Electrical Protective Equipment29 CFR1910.137
(59 FR 4435)

1. Design Requirements
2. In-service Care and Use

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Electrical Protective Equipment29 CFR1910.137
(59 FR 4435)

• (a)Design Requirements
• Insulating blankets,matting, covers, line hose,
  gloves, and sleeves made of rubber shall meet
  specified requirements for manufacture, marking,
  electrical properties, workmanship and finish.

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(b) In-service Care and Use

• Electrical protective equipment shall be
  maintained in a safe, reliable condition.
• Specific requirements for in-service care and use
  are given for insulating blankets, covers, line
  hose, gloves, and sleeves made of rubber.

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Qualified Employee(Qualified Person)

• One knowledgeable in the construction and
  operation of the electric power generation,
  transmission, and distribution equipment
  involved, along with the associated hazards.

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Qualified Employee(Qualified Person)

• Must have the training required by
  paragraph(a)(2)(ii).
• Has undergone on-the-job training and has
  demonstrated an ability to perform duties safely
  under the direct supervision of a qualified
  person.

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• One employee was climbing a metal ladder to
  hand an electric drill to the journey installer
  on a scaffold about five feet above him. When the
  victim reached the third rung from the bottom of
  the ladder he received an electric shock that
  killed him.

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• The employee was attempting to correct an
  electrical problem involving two non-operational
  lamps. He proceeded to the area where he thought
  the problem was. He had not shut off the power at
  the circuit breaker panel nor had he tested the
  wires to see if they were live. He was
  electrocuted when he grabbed the two live wires
  with his left hand and then fell from the ladder.