Electrical Safe Work Practice Region IV - OSHA
Standard Outline • .331 Scope • .332 Training • .333 LOTO – MAD’s – Safe Work Practices • .334 Use of Equipment Portable, Fixed, Test • .335 PPE and Warning
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;
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.
Qualified Person • One familiar with the construction and operation of the equipment and the hazards involved.
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.
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.
.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.
.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.
.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.
.333Work Practices • Written procedure. • De-energize equipment & release stored energy. • Apply locks & tags. • Verify de-energization & test. • Re-energize.
.333Work Practices • Capable of working live & familiar with techniques, PPE – Insulating, shielding materials, insulated tools. • Overhead lines – MAD’s. • Adequate illumination & no blind reaching. • Shielding provided for enclosed spaces.
Tools Non-Rated tool with cushioned grip. Rated insulated tool . Tool should be marked with rating.
.333Work Practices • No conductive materials or equipment. • Nonconductive ladders. • No conductive apparel. • Housekeeping – no steel wool or conductive liquids.
.334(a) Use of Portable Equipment • Covers cordsets (extension cords). • Cord & Plug connected equipment. • For qualified & unqualified workers.
.334(a) Use of Portable Equipment • Don’t 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)
.334(a) Use of Portable Equipment • Extension cords shall be grounded unless used with double insulated tools. (a)(3)(i) • Don’t mess with the grounding pin. (a)(3)(ii) • No 3-wire grounding adapters, unless the ground continuity is maintained. (a)(3)(iii)
.334(a) Use of Portable Equipment • Damp/Wet locations require equipment approved for same. (a)(4) see .303(b)(2) • Don’t plug in or unplug stuff with wet hands. (a)(5) • Twist lock connectors must be locked before use. (a)(5)(iii)
.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.
.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.
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.
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.
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.
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.
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
.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.
.335(a)(2)Protective Equipment • Shall use insulated tools and handling equipment (ASTM 1505 specifications). • Fuse pullers. • Nonconductive rope. • Protective shields & barriers.
.335(b)Alerting Techniques • Signs • Barricades • Attendants