Transcript Electrical Safe Work Practice

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
• Based in part
on NFPA 70 E
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.
.333
Work Practices
 Written procedure.
 De-energize equipment & release
stored energy.
 Apply locks & tags.
 Verify de-energization & test.
 Re-energize.
.333
Work 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.
Insulated Tools
.333
Work 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.
.335
Protective 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.
1910.137(b)(2)(ii):
Air Testing of Rubber Gloves
1910.137(b)(2)(viii): Rubber
Insulating Equipment Test Intervals
Equip.
Line hoses
When to Test
Insulation suspect
Covers
Insulation suspect
* Blankets
Every 12 months
* Gloves
Every 6 months
* Sleeves
Every 12 months
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
Available Fault Current Example
.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
Thank You For
Your Interest in
Job Safety &
Health.