ELECTRICAL HAZARDS. SHOCK. Electric shock occurs when the human body becomes part of the path...

ELECTRICAL HAZARDS

ELECTRICAL HAZARDS• SHOCK. Electric shock occurs when the

human body becomes part of the path through which current flows.

• The direct result can be electrocution.

• The indirect result can be injury resulting from a fall or movement into machinery because of a shock

ELECTRICAL HAZARDS

• BURNS. Burns can result when a person touches electrical wiring or equipment that is energized.

• ARC-BLAST. Arc-blasts occur from high- amperage currents arcing through the air. This can be caused by accidental contact with energized components or equipment failure.

ELECTRICAL HAZARDS

• ARC-BLAST. The three primary hazards associated with an arc-blast are:

• Thermal radiation.

• Pressure Wave.

• Projectiles.

ELECTRICAL HAZARDS

• EXPLOSIONS. Explosions occur when electricity provides a source of ignition for an explosive mixture in the atmosphere.

ELECTRICAL HAZARDS

• FIRES. Electricity is one of the most common causes of fires both in the home and in the workplace. Defective or misused electrical equipment is a major cause.

EFFECTS ON THE HUMAN BODY

Depends on:

Current and Voltage

Resistance

Path through body

Duration of shock

Effects of AC Electricity

• More than 3 mA- Painful shock- cause indirect accident

• More than 10 mA- Muscle contraction – “No Let Go” danger

• More than 30 mA- Lung paralysis, usually temporary

Effects of AC Electricity

• More than 50 mA- Ventricular fibrillation, usually fatal

• 100 mA to 4 A- Certain ventricular fibrillation, fatal

• Over 4 A- Heart paralysis, severe burns

1910.303(b)Examination of equipment

• Electrical equipment must be free of recognized hazards that are likely to cause death or serious physical harm to employees.

1910.303(b)Examination of equipment

Safety of equipment must be determined using the following considerations:

Suitability for installation and use

Mechanical strength and durability

Electrical insulation

Heating effects under conditions of use

1910.303(b)Examination of equipment

Safety of equipment must be determined using the following considerations:

• Arcing effects

• Classification by type, size, voltage, current capacity and specific use

• Other factors

1910.303(c)Splices

Conductors must be spliced with:

Splicing devices suitable for the use

Brazing, welding or soldering (with a mechanically and electrically secure joint before soldering & then soldered)

1910.303(c)Splices

• All splices and joints and the free ends of conductors must be covered with an insulation equivalent to that of the conductors or with an insulating device suitable for the purpose.

1910.303(e)Marking

• Electrical equipment may not be used unless the manufacturer’s name, trademark or other identification is on the equipment.

1910.303(e)Marking

• Other markings must be provided giving voltage, current, wattage, or other ratings as necessary.

• Markings must be durable enough to withstand the environment.

1910.303(f)Identification

• Each disconnecting means must be legibly marked to indicate its purpose, unless located and arranged so that its purpose is evident.

1910.303(f)Identification

• These markings must be durable enough to withstand their environment.

1910.303(g)(1)600 volts, nominal, or less

Working space about electrical equipment.

This section refers to a person qualified to work on electrical equipment, usually an electrician.

1910.303(g)(1)(i)Working clearances

• Except as required or permitted, the dimension of the working space in front of live parts (operating at 600 volts or less) and likely to require examination, adjustment, servicing, or maintenance must be at least three feet.(See table S-1).

1910.303(g)(1)(i)Working clearances

• The workspace in front of electrical equipment must not be less than 30 inches wide.

1910.303(g)(1)(ii)Working clearances

• Working spaces required for this standard may not be used for storage.

1910.303(g)(2)600 Volts or less

Guarding of live parts operating at 50 Volts or more.

The purpose of this requirement is to protect any person who is in the vicinity of electrical equipment against accidental contact, not just electricians.

1910.303(g)(2)600 Volts or less

Guarding of live parts.

(i) Guard against accidental contact by:

(A) Location accessible only to qualified persons

(B) Permanent, substantial partitions or screens

1910.303(g)(2)600 Volts or less

Guarding of live parts.

(i) Guard against accidental contact by:

(C) Location on a suitable elevated balcony or platform

(D) Elevation of 8 feet or more above the floor or other working surface

1910.303(g)(2)600 Volts or less

Guardian of live parts.

In locations where electrical equipment would be exposed to physical damage, enclosures or guardians must be so arranged and of such strength as to prevent such damage.

1910.303(h)(3)Over 600 Volts

Workspace around equipment.

Sufficient space must be provided and maintained around electrical equipment to permit ready and safe operation and maintenance.

1910.303(h)(3)(ii)Illumination (Over 600 Volts)

• Adequate illumination must be provided for all working spaces around electrical equipment.

• The lights and switches must be arranged so that persons making repairs or turning on lights wont contact live ports.

1910.303(h)(3)(iii)Elevation of unguarded live parts

• Unguarded live parts above working space must be maintained at elevations not less than specified in Table S-3.

• The minimum is 8 feet.

1910.304(a) Grounded and grounding conductors

(1) Identification of conductors.

The grounded conductor is an energized circuit conductor that is connected to earth through the system ground. It is commonly referred to as the neutral.

1910.304(a) Grounded and grounding conductors(1) Identification of conductors.

The equipment grounding conductor is not an energized conductor under normal conditions. It is energized only if there is a leak or fault in the normal current path and directs current back to the source.

1910.304(a) Grounded and grounding conductors

(1) Identification of conductors.

The National Electric Code requires that:

The grounded conductor (neutral) be continuous white or natural gray.

The equipment grounding conductor be green, green with yellow stripes or bare.

1910.304(a)(2)Polarity of connections

No grounded conductor may be attached to any terminal or lead so as to reverse designated polarity.

1910.304(a)(2)Polarity of connections

Reversed polarity is a condition when neutral conductor is incorrectly connected to the “hot” terminal of a plug, receptacle or other connector.

1910.304(e)Overcurrent protection

(1) 600 volts or less.

(i) Conductors and equipment must be protected from overcurrent.

1910.304(e)Overcurrent protection

(1) 600 volts or less.

Fuses and circuit breakers are designed to disconnect a circuit from its supply source when a maximum allowable heat is reached.

1910.304(e)Overcurrent protection

(1) 600 volts or less

(iv) Location. Overcurrent devices must be readily accessible but not located where they will be exposed to physical damage or in the vicinity of easily ignitable material.

1910.304(f)Grounding

(4) Grounding path.

The path to ground from circuits, equipment, and enclosures must be permanent and continuous

1910.304(f)Grounding

(5)(v) Tools likely to be used in wet and conductive locations need not be grounded if supplied through an isolating transformer with an ungrounded secondary of not over 50 volts.

1910.304(f)Grounding

(5)(v) Listed or labeled portable tools and appliances protected by an approved system of double insulation, or its equivalent, need not be grounded. However, they must be distinctively marked.

Electrical ToolsDouble Insulated

• They work with GFCIs

• Casing must be labeled

• Tool must be inspected

• Extension cord must be three-prong

1910.305(a)Wiring methods.

(1) General requirements.

(ii) No wiring system of any type shall be in ducts used to transport dust, loose stock or flammable vapors, or used for vapor removal or ventilation of commercial-type cooking equipment.

1910.305(a)Wiring methods.

(2) Temporary wiring.

Temporary electrical power and lighting wiring may be of a class less than would be required for a permanent installation.

1910.305(a)Wiring methods.

(2) Temporary wiring.

(i) Uses permitted, 600 volts or less.

(A) During and for remodeling, maintenance repair, or demolition or similar activities.

1910.305(a)Wiring methods.

(i)Uses permitted, 600 volts or less.

(B) For experimental or developmental work

(C) For a period not to exceed 90 days for Christmas decorative lighting, carnivals, and similar purposes.

1910.305(a)Wiring methods.

(2) Temporary wiring.

(i) Uses permitted, over 600 volts.

Only during tests, experiments and emergencies.

1910.305(a)Wiring methods.

(F) Lamps for general illumination must be protected from accidental contact or breakage.

Protection can be provided by an elevation of 7 feet or by a suitable fixture with a guard.

1910.305(a)Wiring methods.

(G) Flexible cords and cables must be protected from accidental damage.Sharp corners or projections must be avoided.

Protection must be provided when passing through doorways or other pinch points.

1910.305(b)(1)Conductors entering boxes,

cabinets, or fittings.

• Conductors entering boxes, cabinets, or fittings must be protected from abrasion.

• Unused openings in cabinets, boxes, and fittings must be effectively closed.

1910.305(b)(2)Electrical box covers

• All pull boxes, junction boxes, and fittings must be provided with approved covers.

• Metal covers must be grounded.

1910.305(b)(2)Electrical box covers

• Outlet boxes must have a cover or a faceplate.

• Outlet box covers with holes for flexible cords must bushings or smooth, well- rounded surfaces.

1910.305(d)Switchboards and panelboards.

• Panelboards must be mounted in approved cabinets or boxes and must be dead front.

• Others are accessible only to qualified persons.

1910.305(g)(1)(i)Flexible cords and cables.

Allowed uses:

Pendants

Wiring fixtures

Portable lamps or appliances

Elevator cables

Wiring cranes or hoists

1910.305(g)(1)(i)Flexible cords and cables.

Allowed uses:

Connect stationary equipment to facilitate frequent interchange

Prevent transmission of noise or vibration

For removal for maintenance/repair

1910.305(g)(1)(iii)Flexible cords and cables.

May not be used:

As a substitute for the fixed wiring of a structure.

Where run through holes in walls, ceilings or floors.

1910.305(g)(1)(iii)Flexible cords and cables.

May not be used:

Where run through doorways, windows, or similar openings

Where attached to building surfaces

Where concealed behind building walls, ceilings, or floors.

1910.305(g)(2)Flexible cords and cables.

(ii) Flexible cords must be used only in continuous lengths without splice or tap.

1910.305(g)(2)Flexible cords and cables.

(ii) Hard service flex cords, No. 12 or larger, may be repaired if spliced so that the splice retains the insulation, outer sheath properties, and usage characteristics of the original cord.

1910.305(g)(2)Flexible cords and cables.

(iii) Flexible cords must be connected to devices and fittings so that strain relief is provided which will prevent pull off from being directly transmitted to joints or terminal screws.

1910.305(j)Equipment for general use.

(2)(ii) A receptacle installed in a wet or damp location must be suitable for the location.

1910.307Hazardous (classified) locations.

(b) Electrical installations.

Equipment, wiring, and installations of equipment in hazardous (classified) locations must be intrinsically safe, approved for the location, or safe for the location.

Hazardous LocationsClass I locations

• Locations in which flammable gasses or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures.

Hazardous LocationsClass I, Division 1

Location in which hazardous concentrations of flammable gases or vapors may exist:

(a) Under normal operating conditions

(b) Because of repair or maintenance operations or leakage

(c) Because of breakdown or faulty operation

Hazardous LocationsClass I, Division 2

Location in which flammable gases or vapors are:

(a) Normally confined within closed containers or systems

(b) Normally kept below hazardous concentrations by ventilation

(c) Normally kept below hazardous concentrations by positive-pressure ventilation (adjacent to Division 1)

Hazardous LocationsClass II Locations

Locations which are hazardous because of the presence of combustible dust.

Hazardous LocationsClass II, Division 1

Location where combustible dust may be present due to:

(a) Normal operations

(b) Mechanical failure or abnormal operation of machinery or equipment

(c) combustible dust of an electrically conductive nature may be present.

Hazardous LocationsClass II, Division 2

Location where:

(a) Combustible dust will not normally be in suspension in ignitable quantities

(b) Dusts may be in suspension as a result of an infrequent malfunction of handling or processing equipment.

Hazardous LocationsClass III Locations

Locations that are hazardous because of the presence of easily ignitable fibers or flyings but in which such fibers or flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitable mixtures.

Hazardous LocationsClass III, Division 1

Locations in which easily ignitable fibers or materials producing combustible flyings are handled, manufactured or used.

Hazardous LocationsClass III, Division 2

Location in which easily ignitable fibers are stored or handled, except in the process of manufacture.

1910.331 - .335Electrical Safe Work Practices

Covers work practices rather than electrical equipment and installations.

This should be a part of your Lockout/Tagout program

Electrical Protective Equipment29 CFR1910.137 (59 FR 4435)

(a) Design Requirements

(b) In-service Care and Use

Electrical Protective Equipment29 CFR1910.137 (59 FR 4435)

(a)Design Requirements

Insulating blankets,matting, covers, line hose, gloves, and sleeves made of rubber shall meet specified requirements for manufacture, marking, electrical properties, workmanship and finish.

(b) In-service Care and Use

• Electrical protective equipment shall be maintained in a safe, reliable condition.

• Specific requirements for in-service care and use are given for insulating blankets, covers, line hose, gloves, and sleeves made of rubber.

Qualified Employee(Qualified Person)

One knowledgeable in the construction and operation of the electric power generation, transmission, and distribution equipment involved, along with the associated hazards.

Qualified Employee(Qualified Person)

• Must have the training required by paragraph(a)(2)(ii).

• Has undergone on-the-job training and has demonstrated an ability to perform duties safely under the direct supervision of a qualified person.

One employee was climbing a metal ladder to hand an electric drill to the journey installer on a scaffold about five feet above him. When the victim reached the third rung from the bottom of the ladder he received an electric shock that killed him.

The employee was attempting to correct an electrical problem involving two non-operational lamps. He proceeded to the area where he thought the problem was. He had not shut off the power at the circuit breaker panel nor had he tested the wires to see if they were live. He was electrocuted when he grabbed the two live wires with his left hand and then fell from the ladder.