Electrical Safe Work Practice

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Electrical Safe Work Practice

• Region IV - OSHA

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Standard Outline

• .331 Scope
• .332 Training
• .333 LOTO MADs Safe Work Practices
• .334 Use of Equipment Portable, Fixed, Test
• .335 PPE and Warning

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• Based in part on NFPA 70 E

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Premises Wiring

• Installations of electric conductors and
  equipment within or on buildings or other
  structures, and on other premises such as yards,
  carnival, parking, and other lots, and industrial
  substations

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Equipment

• A general term including material, fittings,
  devices, appliances, fixtures, apparatus, and the
  like, used as a part of, or in connection with,
  an electrical installation.

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Qualified Person

• One familiar with the construction and operation
  of the equipment and the hazards involved.

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Qualified Person

• If their work exposes them to electrical hazards
  which would otherwise be protected according to
  Subpart S They must protect themselves against
  ALL the electrical hazards.
• Hazards include Shocks, Electrocution, Arc
  Blast, Burns, Explosions.

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Unqualified Person

• Normally protected by Subpart S.
• However
• If their work exposes them to electrical hazards
  which would otherwise be protected according to
  Subpart S They must be trained.

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.332(a)Training

• Employees who face a risk of electric shock that
  is not reduced to a safe level by the electrical
  installation requirements of 1910.303 through
  1910.308.

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.332(b)(2)Training

• Employees who are covered by paragraph (a) of
  this section but who are not qualified persons
  shall also be trained in and familiar with any
  electrically related safety practices not
  specifically addressed by 1910.331 through
  1910.335 but which are necessary for their
  safety.

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.333 Work Practices

• Live parts (50 Volts or more) shall be
  de-energized before working on them.
• Unless the employer can demonstrate infeasibility
  or greater hazard.

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.333Work Practices

• Written procedure.
• De-energize equipment release stored energy.
• Apply locks tags.
• Verify de-energization test.
• Re-energize.

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.333Work Practices

• Capable of working live familiar with
  techniques, PPE Insulating, shielding
  materials, insulated tools.
• Overhead lines MADs.
• Adequate illumination no blind reaching.
• Shielding provided for enclosed spaces.

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Tools
Rated insulated tool . Tool should be marked
with rating.

• Non-Rated tool with cushioned grip.

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Insulated Tools
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.333Work Practices

• No conductive materials or equipment.
• Nonconductive ladders.
• No conductive apparel.
• Housekeeping no steel wool or conductive
  liquids.

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.334(a) Use of Portable Equipment

• Covers cordsets (extension cords).
• Cord Plug connected equipment.
• For qualified unqualified workers.

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.334(a) Use of Portable Equipment

• Dont abuse, damage, or use for a rope. (a)(1)
• Visually inspect before use. (a)(2)
• Shall be removed from service not used until
  repaired. (a)(2)(ii)

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.334(a) Use of Portable Equipment

• Extension cords shall be grounded unless used
  with double insulated tools. (a)(3)(i)
• Dont mess with the grounding pin. (a)(3)(ii)
• No 3-wire grounding adapters, unless the ground
  continuity is maintained. (a)(3)(iii)

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.334(a) Use of Portable Equipment

• Damp/Wet locations require equipment approved for
  same. (a)(4) see .303(b)(2)
• Dont plug in or unplug stuff with wet hands.
  (a)(5)
• Twist lock connectors must be locked before use.
  (a)(5)(iii)

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.334(c)Test Equipment

• Test instruments used only by qualified
  employees.
• Visually inspected before use, including leads
  and probes.
• Rating of equipment (voltage)
• Test leads rated for full voltage.
• Designed for environment.

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.335Protective Equipment

• Employees working in areas where they are no
  potential electrical hazards shall use
  electrical PPE.
• PPE 1910.132 - 1910.138.
• Electrical Protective Equipment ASTM F
  Standards.
• Textile Clothing NFPA 70E ASTM F1506.

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1910.137(b) In-service Care and Use

• Maximum use voltage to conform to Table I-5.
• Equipment damage inspection
• No holes, tears, cuts, or punctures no ozone
  cutting or checking no embedded foreign objects
  no swelling, softening, hardening, etc.

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1910.137(b)(2)(ii)Air Testing of Rubber Gloves
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1910.137(b)(2)(viii) Rubber Insulating
Equipment Test Intervals
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Electric Arc Hazards

• Electric Arcs can reach temperatures of 34,000oF
• The arcs can vaporize metal, burn skin, and
  ignite clothing.
• Vaporized copper expands 67,000 times in volume.
• High pressures can develop in enclosures, causing
  covers and molten metal to fly.

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Arc Hazards

• When clothing ignites, it can greatly increase
  the amount of skin area burned, and the chance of
  a fatality.
• Heat levels of 1.2 cal/cm2 per second for one
  second can cause second degree burns to exposed
  skin.
• Most arc exposure times are less than 1 second.

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Arc Hazards

• Regular cotton work clothing will typically not
  ignite at heat levels up to 1-2 cal/cm2.
• Heavy denim might work for about 5-10 cal/cm2.

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Arc Heat Example

• 480 Volt arc in a box. 6 cycles, at a 12 inch
  distance.
• 16,000A 8 - 11 cal/cm2
• 24,000A 9 14 cal/cm2
• 38,000A 17 24 cal/cm2
• 50,000A 32 38 cal/cm2

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Available Fault Current Example
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.335(a)(1)Protective Equipment

• Maintain periodically test according to .137.
• Protect the insulating capability against damage.
• Nonconductive head protection.
• Face Eye Protection for arc blast.

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.335(a)(2)Protective Equipment

• Shall use insulated tools and handling equipment
  (ASTM 1505 specifications).
• Fuse pullers.
• Nonconductive rope.
• Protective shields barriers.

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.335(b)Alerting Techniques

• Signs
• Barricades
• Attendants

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Thank You For Your Interest in Job Safety
Health.