Electrical

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.

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260 14th Street, Fourth FloorAtlanta, GA 30332-0837

Voice : (404) 407-7431 FAX : (404) 407-8275

Web http://www.oshainfo.gatech.edu


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


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)GA Tech Health and Safety

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CONCEPTS /DEFINITIONSGrounding 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


CONCEPTS /DEFINITIONS...

Receptaclea 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


CURRENT LEAKAGESAny 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


WHICH ARE THE HAZARDS?

ELECTRICAL BURNSmay happen when a person makes physical

contact with live electrical wiring and/or energized electrical equipment which is improperly maintained or used

ELECTRICAL EXPLOSIONSmay occur due to a short circuit at a phase to

ground or when an electrical current becomes the ignition source in an explosive atmosphere



;A

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)


HAZARDS ...

FIRES:Electricity is one of the most frequent causes

of fires in homes and work placesA leading cause of fires is the use of defective

electrical equipment or using it incorrectly



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


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




A

GUARDING OF LIVE PARTSElectrical equipment operating at 50 volts

or more shall be guarded to protect against accidental contactcabinetsenclosures

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 personsOnly qualified persons can access these

enclosures




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


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 conditionthe 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.






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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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



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


ACCESS

When using extension cords in the working area or access routes for personnelThey must be laid/extended in such a way so

that they do not present a hazard to workers



WARNING LABELS /SIGNSHigh voltage equipment or installations must

be labeled using self-adhesive warning labels or informative signs




TEMPORARY RECEPTACLES

Temporary power receptacles must have approved covers

If the receptacle covers are metal, they must also be connected to a ground wire.



LOCKOUT AND TAGGING OF CIRCUITS (Lock Out/Tag Out)

If equipment will be temporarily deactivated during the project, padlocks and identifying tags must be installedThis applies to energized or de-energized

equipment



PREVENTING AND ELIMINATING HAZARDSGFCI’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 connectionThe current exceeds the rated current of equipment

or tools (overload)Having an Assured Grounding Protection Program

is also an acceptable optionRelies on a competent person to continuously monitor

(“assure”) that the ground circuit is maintained.



EMPLOYER’S RESPONSIBILITIESOSHA 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


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



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.


GROUNDING CIRCUIT INTERRUPTERSAn 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


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


PROGRAM…OSHA asks for two tests to be performed

using an electricity meter:1. All equipment grounding conductors shall

be tested for continuity and shall be electrically continuous

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.

2. Test that each electrical receptacle and attachment cap or plug’s grounding conductor is connected to its proper terminal.



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 andat 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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