29 CFR 1926.400
SECTION K
GA Tech Health and Safety
Consultation Program
INTRODUCTION
This training information has been prepared by the Safety and Health Consultation
Program at Georgia Tech with the technical collaboration of Mr. Juán C. Rodriguez and
under the sponsorship of OSHA. Its content may be copied and distributed for free, and
the only request made to the user is that Georgia Tech’s Safety and Health Consultation
Program be acknowledged as the source. All information contained in this training is
believed to be correct by the authors, but it is important to point out that, this is not an
official OSHA publication and has not been revised or approved by OSHA. The user
should be aware that the recommendations provided in this training do not replace any
OSHA standard or regulation.
Georgia Tech Safety and Health Consultation Program
Georgia Tech Research Institute
260 14th Street, Fourth Floor
Atlanta, GA 30332-0837
Voice : (404) 407-7431
FAX : (404) 407-8275
Web http://www.oshainfo.gatech.edu
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WHY?
 As a result of the frequent use of electrical tools in
the construction field, it is often necessary to make
temporary use of flexible extension cords.
 Hazards related to extension cords arise when
 the cords, their attached plugs (connectors), and
receptacles are utilized in an unsafe or incorrect manner,
or
 a piece of equipment powered using an extension cord
does not receive adequate maintenance.
 Temporary, flexible extension cords are often more
vulnerable to damage than permanent electrical
installations
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WHY?
 Electrical extension cords are normally unprotected
and flexible, their connections (plugs) and entire
length become vulnerable.
 As with electrical tools, electrical extension cords
may be damaged as a result of
 different working activities around them,
 sharp corners and edges of doors and windows or
other pinch points,
 contact with abrasive materials, or
 the effects of environmental conditions (i.e., heat,
moisture)
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CONCEPTS /DEFINITIONS
 Grounding Connection
 A direct conducting connection, whether intentional or
accidental, between an electrical circuit or equipment
and the earth, or to some conducting body that serves in
place of the earth
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CONCEPTS /DEFINITIONS...
 Receptacle
 a contact device installed at the outlet of an electrical
system for the connection of a single attachment plug,
and from which electrical current is supplied to a piece
of equipment or tool
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CURRENT LEAKAGES
 Any current leak from an electrical tool will follow
the path of least resistance to ground
 If the grounding conductor has a high resistance
(impedance) then the worker’s body may become
the path of least resistance
 To prevent a current leak from causing an electric
shock to the operator, the resistance of the
grounding conductor must not exceed 1 ohm
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WHICH ARE THE HAZARDS?
 ELECTRICAL BURNS
 may happen when a person makes physical contact with
live electrical wiring and/or energized electrical
equipment which is improperly maintained or used
 ELECTRICAL EXPLOSIONS
 may occur due to a short circuit at a phase to ground or
when an electrical current becomes the ignition source
in an explosive atmosphere
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;
A
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HAZARDS...
 ELECTRICAL SHOCKS
 Occur when the human body becomes part of the
electrical circuit
 A direct result may be electrocution
 Indirect results:

serious injuries or death resulting from a fall from an
elevated location (e.g., off a roof, scaffolding, or ladder)
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HAZARDS ...
 FIRES:
 Electricity is one of the most frequent causes of fires in
homes and work places
 A leading cause of fires is the use of defective electrical
equipment or using it incorrectly
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EFFECTS OR CONSEQUENCES TO THE HUMAN
BODY
 Will depend upon:
 Amount of current and voltage
 The resistance through a grounding conductor (wire)
 Path of the current through the body
 Length of time the body is part of the circuit
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EXAMINATION, INSTALLATION AND USE OF EQUIPMENT
 The employer shall ensure that electrical equipment is
free from recognized hazards that could cause serious
physical harm to employees
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A
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GUARDING OF LIVE PARTS
 Electrical equipment operating at 50 volts or more
shall be guarded to protect against accidental
contact
 cabinets
 enclosures
 The entrance to an area containing exposed live
parts operating at 600 volts, nominal, or more shall
be enclosed and kept locked to prevent access to
unqualified persons
 Only qualified persons can access these enclosures
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GA Tech Health and Safety
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GROUNDING CONDUCTOR OF AN EQUIPMENT
CONNECTED (ENERGIZED) BY CORD AND PLUG
 All exposed/unprotected extension cords and their
plugs may have current leakages; therefore, they
shall have a grounding conductor to prevent
electrical shocks to people, particularly if the
extension cords are being used to energized hand
held motor-operated tools, or equipment used in
damp or wet locations or by employees standing on
the ground or on metal floors which might become
energized
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EXTENSION CORDS
 All temporary, flexible, power extension cords shall comply
with all applicable safety requirements for the intended
activity.
 Both, the extension cord and its plugs, as well as its
insulating material (covering) shall be in perfect condition
 the plugs must always have the grounding pin in place.
 If the extension cords have to be run through holes in walls,
ceilings or floors or similar openings, then they shall be
protected from sharp corners, projections, pinch points, and
sharp edges.
 Extension cord sets must not be used in extremely damp or
wet locations, nor can they be exposed to excessive
temperatures, unless they have been specifically designed by
the manufacturer for such use.
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MOTORS
 Motors operating at over 600 volts, nominal, shall be
equipped with/connected to a visible and manually
operated button for starting it (ON) and for stopping it
(OFF) at the location of the motor
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GA Tech Health and Safety
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GA Tech Health and Safety
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PROTECTION OF EMPLOYEES
 NO EMPLOYER shall permit an employee to
work in such proximity to any part of an electric power
circuit that the employee could contact the electric
power circuit in the course of work, unless the
employee is protected against electric shock by
deenergizing the circuit and grounding it or by
guarding it effectively by insulation or other means
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GA Tech Health and Safety
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PROTECTION…
 Two most common methods of preventing
electrical accidents on jobsites:
 use of insulating material (e.g., insulating material
encasing an electrical extension cord)
 a grounding connector (e.g., Ground Fault Circuit
Interrupters (GFCI’s) are the most common method
for eliminating grounding problems
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ACCESS
 When using extension cords in the working area or
access routes for personnel
 They must be laid/extended in such a way so that they
do not present a hazard to workers
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WARNING LABELS /SIGNS
 High voltage equipment or installations must be
labeled using self-adhesive warning labels or
informative signs
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TEMPORARY RECEPTACLES
 Temporary power
receptacles must have
approved covers
 If the receptacle covers are
metal, they must also be
connected to a ground wire.
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LOCKOUT AND TAGGING OF CIRCUITS
(Lock Out/Tag Out)
 If equipment will be temporarily deactivated during
the project, padlocks and identifying tags must be
installed
 This applies to energized or de-energized equipment
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PREVENTING AND ELIMINATING HAZARDS
 GFCI’s are effective at preventing electrical hazards in
construction sites and the most commonly used option
 GFCIs will activate or be triggered if
 the current comes in contact with moisture
 At the receptacle or at any connection
 The current exceeds the rated current of equipment or tools
(overload)
 Having an Assured Grounding Protection Program is also
an acceptable option
 Relies on a competent person to continuously monitor
(“assure”) that the ground circuit is maintained.
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EMPLOYER’S RESPONSIBILITIES
 OSHA regulations state that for the safety and
well-being of workers the employer must
provide the following:
a) Ground Fault Circuit Interrupters (GFCI’s)
for electrical equipment and temporary
installations used to provide electric power
at the jobsite (Most Common)
b) An Assured Grounding Protection Program
with its corresponding scheduled and
documented inspections
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WHAT IS A GFCI?
 A GFCI is a switch that immediately shuts off a circuit
if a fault (short circuit) is noted.
 A GFCI continuously compares the amount of current
that flows to an electrical tool with the amount of
current that returns from the tool
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GA Tech Health and Safety
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GFCI…cont
 The GFCI monitors the current supplied to a circuit
(usually the black wire) and compares that to the
current returning on the grounded wire (usually the
white wire).

If a difference of 5 milliamps or greater in current is noted, the
GFCI assumes a short to ground has happened, and within
1/40 second, shuts off the circuit.
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GROUNDING CIRCUIT INTERRUPTERS
 An employer must use approved GFCI’s for all 120-
volt, single phase, 15 and 20 ampere receptacle
outlets on construction sites that are not part of the
permanent wiring of the building or structure and
which are in use by employees
 Since the receptacles for the temporary electrical
extension cords are not permanent parts of the
building, they must be protected by a GFCI,
regardless of whether or not they are connected to
the permanent electrical system
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ASSURED EQUIPMENT GROUNDING CONDUCTOR
PROGRAM
 This program covers the extension cords and
electrical receptacles which are not a permanent
part of the electrical system of a building, but
which are available and accessible to workers
 OSHA asks for a written description of the program
which specifies the procedures to be adopted. This
written description shall be available at the work
site
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PROGRAM…
 OSHA asks for two tests to be performed using an
electricity meter:
All equipment grounding conductors shall be
tested for continuity and shall be electrically
continuous
1.

2.
this must be performed on all cord sets and electrical
receptacles that are not a part of the permanent wiring
of the building or structure, and on all cord-and-plug
tools.
Test that each electrical receptacle and attachment
cap or plug’s grounding conductor is connected to
its proper terminal.
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TESTS…
 These two tests shall be performed before equipment,
tools and extension cords are used for the first time and
after any repairs, or when it can be reasonably
suspected :
 That something has been damaged and
 at intervals not to exceed 3 months.
 Normally, adhesive tape of different colors is used to
mark/identify what has been tested
 Equipment that has failed the required tests shall be
taken out of service by tagging it and putting it in a
secured location so that it is not available for use by
employees
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