ELECTRICAL HAZARDS GENERAL CONTROL MEASURES BASIC INFORMATION AND TUTORIALS

General control measures for electrical hazards

The principal control measures for electrical hazards are contained in the statutory precautionary requirements covered by the Electricity at Work Regulations. They are applicable to all electrical equipment and systems found at the workplace and impose duties on employers, employees and the self-employed.

The regulations cover the following topics:

S the design, construction and maintenance of electrical systems, work activities and protective
equipment
S the strength and capability of electrical equipment
S the protection of equipment against adverse and hazardous environments
S the insulation, protection and placing of electrical conductors
S the earthing of conductors and other suitable precautions
S the integrity of referenced conductors
S the suitability of joints and connections used in electrical systems
S means for protection from excess current
S means for cutting off the supply and for isolation
S the precautions to be taken for work on equipment made dead
S working on or near live conductors
S adequate working space, access and lighting
S the competence requirements for persons working on electrical equipment to prevent danger and injury.

Detailed safety standards for designers and installers of electrical systems and equipment are given a code of practice published by the Institution of Electrical Engineers, known as the IEE Regulations. While these regulations are not legally binding, they are recognized as a code of good practice and widely used as an industry standard.

The risk of injury and damage inherent in the use of electricity can only be controlled effectively by the introduction of employee training, safe operating procedures (safe systems of work) and guidance to cover specific tasks.

Training is required at all levels of the organization ranging from simple on-the-job instruction to apprenticeship for electrical technicians and supervisory courses for experienced electrical engineers. First aid training related to the need for cardiovascular resuscitation and treatment of electric burns should be available to all people working on electrical equipment and their supervisors.

A management system should be in place to ensure that the electrical systems are installed, operated and maintained in a safe manner. All managers should be responsible for the provision of adequate resources of people, material and advice to ensure that the safety of electrical systems under their control is satisfactory and that safe systems of work are in place for all electrical equipment

For small factories and office or shop premises where the system voltages are normally at mains voltage, it may be necessary for an external competent person to be available to offer the necessary advice.

Managers must set up a high voltage permit-to-work system for all work at and above 600 volts. The system should be appropriate to the extent of the electrical system involved. Consideration should also be given to the introduction of a permit system for voltages under 600 volts when appropriate and for all work on live conductors.

The additional control measures that should be taken when working with electrical or using electrical equipment are summarized by the following topics:
S the selection of suitable equipment
S the use of protective systems
S inspection and maintenance strategies

HAZARDS OF USING PNEUMATIC TOOLS BASIC INFORMATION AND TUTORIALS

WHAT ARE THE PNEUMATIC TOOLS HAZARD WHEN WORKING?
Hazard of Pneumatic Tools



Pneumatic tools are powered by compressed air and include chippers, drills, hammers, and sanders.
There are several dangers associated with the use of pneumatic tools. First and foremost is the danger of getting hit by one of the tool's attachments or by some kind of fastener the worker is using with the tool.

Pneumatic tools must be checked to see that the tools are fastened securely to the air hose to prevent them from becoming disconnected.

A short wire or positive locking device attaching the air hose to the tool must also be used and will serve as an added safeguard.

If an air hose is more than 12.7 millimeters in diameter, a safety excess flow valve must be installed at the source of the air supply to reduce pressure in case of hose failure.

In general, the same precautions should be taken with an air hose that are recommended for electric cords, because the hose is subject to the same kind of damage or accidental striking, and because it also presents tripping hazards.

When using pneumatic tools, a safety clip or retainer must be installed to prevent attachments such as chisels on a chipping hammer from being ejected during tool operation.

Pneumatic tools that shoot nails, rivets, staples, or similar fasteners and operate at pressures more than 6,890 kPa, must be equipped with a special device to keep fasteners from being ejected, unless the muzzle is pressed against the work surface.

Airless spray guns that atomize paints and fluids at pressures of 6,890 kPa or more must be equipped with automatic or visible manual safety devices that will prevent pulling the trigger until the safety device is manually released.

Eye protection is required, and head and face protection is recommended for employees working with pneumatic tools.

Screens must also be set up to protect nearby workers from being struck by flying fragments around chippers, riveting guns, staplers, or air drills.

Compressed air guns should never be pointed toward anyone. Workers should never "dead-end" them against themselves or anyone else. A chip guard must be used when compressed air is used for cleaning.

Use of heavy jackhammers can cause fatigue and strains. Heavy rubber grips reduce these effects by providing a secure handhold.

Workers operating a jackhammer must wear safety glasses and safety shoes that protect them against injury if the jackhammer slips or falls.

A face shield also should be used. Noise is another hazard associated with pneumatic tools. Working with noisy tools such as jackhammers requires proper, effective use of appropriate hearing protection.

HAZARD CLASSIFICATION IN WORKPLACE SAFETY BASIC INFORMATION AND TUTORIALS

HOW TO CLASSIFY HAZARDS IN WORKPLACE?
Hazard Classifications



Hazards found during an inspection shall be classified so that managers can allocate time and dollars for their correction in order of priority based on the degree of danger present.

Hazards shall be classified as: imminent danger, serious, and non-serious based on the following criteria.

• Imminent danger hazards would likely cause death, severe injury or high property losses immediately, or before the hazard can be eliminated through normal procedures. Immediate employee protection and abatement is required.

An example is a leaking propane gas cylinder in crew quarters.

• Serious hazards are those in which there is high probability that serious injury, illness, ör extensive property damage would result unless corrective action is taken. Abatement shall be accomplished within 14 days.

An example is a broken stair tread.

• Non-serious hazards are those that could cause injury, illness, or property damage. Abatement shall be accomplished in 30 days.

An example is a broken window in a workshop.

ELECTRICAL SAFETY HAZARDS THAT NEEDS TO BE IDENTIFIED ON ELECTRICAL SAFETY WORKS

WHAT ARE THE DIFFERENT ELECTRICAL SAFETY HAZARDS?

Identifying electrical safety hazards.



When electrical systems break down what are the primary hazards and what are the consequences to personnel? Electric shock Exposure to Arc-Flash Exposure to Arc-Blast Exposure to excessive light and sound energies

Secondary hazards may include burns, the release of toxic gases, molten metal, airborne debris and shrapnel. Unexpected events can cause startled workers to lose their balance and fall from ladders or jerk their muscles possibly causing whiplash or other injuries.

Electric Shock
When personnel come in contact with energized conductors they receive a shock with current flowing through their skin, muscles and vital organs. The severity of the shock depends on the current’s path through the body, the current intensity, and the duration of the contact.

They may only experience a mild tingling sensation or it could result in serious injury or death. As voltage levels increase, the effects of electric shock escalate. Current may also cause an erratic heartbeat known as ventricular fibrillation.

If fibrillation occurs even briefly and goes untreated, the effects are usually fatal. A clear understanding of how electric current travels through the body can help minimize injury if such contact occurs. The table below outlines the effects that various values of electrical current have on the human body.

There are three basic pathways electric current travels through the body;

1) Touch Potential (hand/hand path)

2) Step Potential (foot/foot path)

3) Touch/Step Potential (hand/foot path)



1) In a touch potential contact, current travels from one hand through the heart and out through the other hand. Because the heart and lungs are in the path of current, ventricular fibrillation, difficulty in breathing, unconsciousness, or death may occur.

2) In a step potential contact, current travels from one foot through the legs, and out of the other foot. The heart is not in the direct path of current but the leg muscles may contract, causing the victim to collapse or be momentarily paralyzed.

3) In a touch/step potential contact, current travels from one hand, through the heart, down the leg, and out of the foot. The heart and lungs are in the direct path of current so ventricular fibrillation, difficulty in breathing, collapse, unconsciousness, or death may occur.

Even though there may be no external signs from the electrical shock, internal tissue or organ damage may have occurred. Signs of internal damage may not surface immediately; and when it does, it may be too late.

Any person experiencing any kind of electrical shock should seek immediate medical attention. Using the correct personal protective equipment (PPE) and following safe work practices will minimize risk of electrical shock hazards.

Arc-Flash and Arc Blasts 

An Arc-Flash is an unexpected sudden release of heat and light energy produced by electricity traveling through air, usually caused by accidental contact between live conductors. Temperatures at the arc terminals can reach or exceed 35,000 degrees Fahrenheit (F), or four times the temperature of the sun’s surface.

The air and gases surrounding the arc are instantly heated and the conductors are vaporized causing a pressure wave called an Arc Blast. Personnel directly exposed to an Arc-Flash and Arc-Blast events are subject to third degree burns, possible blindness, shock, blast effects and hearing loss. Even relatively small arcs can cause severe injury.

The secondary effect of arcs includes toxic gases, airborne debris, and potential damage to electrical equipment, enclosures and raceways. The high temperatures of the arc and the molten and vaporized metals quickly ignite any flammable materials.

While these fires may cause extensive property damage and loss of production, the hazards to personnel are even greater. Any energized electrical conductor that makes accidental contact with another conductor or with ground will produce an Arc-Flash.

The arcing current will continue to flow until the overcurrent protective device used upstream opens the circuit or until something else causes the current to stop flowing. The arc current can vary up to the maximum available bolted fault current

BEST LOCATIONS FOR PANEL BOARDS AND SWITCH BOARDS OF ELECTRONIC EQUIPMENT BASIC TUTORIALS

Where should panel boards be located?

Switchboards and panelboards that support electronic load equipment and related loads should be properly designed and installed. Recommended practice is to use panelboards specifically listed for nonlinear loads if they serve electronic load equipment.

As a minimum, panelboards should be rated for power or lighting applications, and should not be a lighterduty type. Special attention should be given to the location and installation methods used when installing panelboards.

In addition, protective devices shall adequately protect system components, neutral buses should be sized to accommodate increased neutral currents due to harmonic currents from nonlinear electronic load equipment, and equipment ground buses should be sized to accommodate increased numbers of equipment grounding conductors due to the recommended practices of using insulated equipment grounding conductors and dedicated circuits for electronic load equipment.

Surge protective devices may also be installed external to, or internal to, the switchboards or panelboards.

Location
Panelboards that serve electronic load equipment should be placed as near to the electronic load equipment as practicable, and should be bonded to the same ground reference as the electronic load equipment.

Other panelboards located in the same area as the electronic load equipment that serve other loads such as lighting, heating, ventilation, air conditioning, and process cooling equipment should also be bonded to the same ground reference as the electronic load equipment.

Panelboards should be directly mounted to any building steel member in the immediate area of the installation. Isolation of a panelboard from the metallic building structure by an electrically insulating material, as an attempt to prevent flow of high frequency current through the panelboard, is not recommended practice.

The panelboard and metallic building structure, separated by a dielectric material, become capacitively coupled. The capacitive coupling presents a low impedance at high frequency defeating the original purpose.

NFPA 780-1997 requires effective grounding and bonding between objects such as structural building steel and a panelboard located within side-flash distance (approximately 1.8 m (6 ft), horizontally) of each other. Insulation materials, commonly used in an attempt to separate a panelboard from building steel, are rarely capable of withstanding lightningi nduced arcing conditions.

PROJECT RISK CONTROL - HIERARCHY OF RISK CONTROLS BASIC INFORMATION AND TUTORIALS

When assessing the adequacy of existing controls or introducing new controls, a hierarchy of risk controls should be considered. The Management of Health and Safety at Work Regulations 1999 Schedule 1 specifies the general principles of prevention which are set out in the European Council Directive.

These principles are:
1. avoiding risks
2. evaluating the risks which cannot be avoided
3. combating the risks at source
4. adapting the work to the individual, especially as regards the design of the workplace, the choice
of work equipment and the choice of working and production methods, with a view, in particular, to alleviating monotonous work and work at a predetermined work-rate and to reducing their effects on health
5. adapting to technical progress
6. replacing the dangerous by the non-dangerous or the less dangerous
7. developing a coherent overall prevention policy which covers technology, organization of work, working conditions, social relationships and the influence of factors relating to the working environment
8. giving collective protective measures priority over individual protective measures and
9. giving appropriate instruction to employees.

These principles are not exactly a hierarchy but must be considered alongside the usual hierarchy of risk control which is as follows:

S elimination
S substitution
S engineering controls (e.g. isolation, insulation and
ventilation)
S reduced or limited time exposure
S good housekeeping
S safe systems of work
S training and information
S personal protective equipment
S welfare
S monitoring and supervision
S reviews.

ELECTRICAL PROTECTIVE HIGH TENSION GLOVES BASIC INFORMATION AND TUTORIALS

What are high tension gloves?

High voltage gloves are a form of PPE that is required for employees who work in close proximity to live electrical current. OSHAs Electrical Protective Equipment Standard (29 CFR 1910.137) provides the design guidelines and in-service care and use requirements for electrical insulating gloves and sleeves as well as insulating blankets, matting, covers, and line hoses.

Electrical protective gloves are categorized by the level of voltage protection they provide. Voltage protection is broken down into the following classes:

n Class 0—Maximum use voltage of 1000 V AC/proof tested to 5000 V AC.

n Class 1—Maximum use voltage of 7500 V AC/proof tested to 10,000 V AC.

n Class 2—Maximum use voltage of 17,000 V AC/proof tested to 20,000 V AC.

n Class 3—Maximum use voltage of 26,500 V AC/proof tested to 30,000 V AC.

n Class 4—Maximum use voltage of 36,000 V AC/proof tested to 40,000 V AC.

Once the gloves are issued, OSHA requires that they be maintained in a safe, reliable condition. This means that high voltage gloves must be inspected for any damage before each day’s use, and immediately following any incident that may have caused them to be damaged.

This test method is described in the ASTM section F 496, Specification for In-Service Care of Insulating Gloves and Sleeves. Basically, the glove is filled with air, manually or by an inflator, and then checked for leakage.

The easiest way to detect leakage is by listening for air escaping or holding the glove against your cheek to feel air releasing.

OSHA recognizes that gloves meeting ASTM D 120-87, Specification for Rubber Insulating Gloves, and ASTM F 496, Specification for In- Service Care of Insulating Gloves and Sleeves, meet its requirements.

In addition to daily testing, OSHA requires periodic electrical tests for electrical protective equipment and ASTM F 496 specifies that gloves must be electrically retested every 6 months. Many power utility companies will test gloves and hot sticks for a reasonable fee.

THE SAFETY-RELATED CASE FOR ELECTRICAL MAINTENANCE

The relationship between safety and preventive maintenance is not a difficult one to establish. Properly designed equipment that is properly installed is well capable of doing its job when it is new.

As equipment ages however, several factors begin to take their toll on electrical equipment.

● Dust, dirt, and other contaminants collect on equipment causing the equipment to overheat and bearings and other moving parts to bind.

● Vibration causes hardware to loosen. Subsequent operations of equipment can cause joints and equipment to fail explosively.

● Heat and age can cause insulation to fail, resulting in shock hazards to personnel.

● Increased loads, motor starting surges, and power quality issues such as harmonics combine to increase the aging process and set the stage for equipment failure.

Unfortunately, the ultimate failure of unmaintained equipment usually occurs when the equipment is needed the most—during electrical faults. Such failures result in arc and blast events that can and do harm workers in the area.

They also result in significant downtime, loss of equipment, and construction cost incurred in rebuilding the equipment. The only way to ensure that electrical equipment continues to operate in an optimal manner is to maintain it so that it stays in factory-new-operating condition.

Regulatory
As discussed above and in previous chapters, the catastrophic failure of electrical equipment creates severe hazards for personnel working in the area. Recognizing this the

Standard for Electrical Safety in the Workplace (NFPA 70E)3 requires that electrical equipment be properly maintained to minimize the possibility of failure.

Relationship of Improperly Maintained Electrical Equipment to the Hazards of Electricity

Improperly maintained equipment may expose workers to any of the three electrical hazards. For example:

1. Improperly maintained tools or flexible cord sets (extension cords) can have frayed insulation which exposes the energized conductors and allows them to contact the worker or the metallic tool the worker is using. The result is an electric shock.

2. Improperly maintained protective devices, such as circuit breakers or fuses, can fail when interrupting an overcurrent. Such a failure is likely to be explosive; consequently, the worker is exposed to electrical arc and electrical blast.

3. Improperly maintained connections can overheat resulting in any of the following:
a. melted insulation, exposed conductors, and the attendant electrical shock hazard
b. fire
c. failed connections resulting in electrical arc and blast

4. Improperly maintained switchgear, motor control centers, or panelboards can fail explosively when an arc occurs internally. This exposes workers to the effects of electrical blast and possibly electrical arc.

THE USE OF GROUND FAULT CURRENT INTERRUPTER (GFCI) IN SAFE ELECTRICAL SYSTEM

A groundfault circuit interrupter (GFCI) is an electrical device which protects personnel by detecting potentially hazardous ground faults and immediately disconnecting power from the circuit. Any current over 8 mA is considered potentially dangerous depending on the path the current takes, the amount of time exposed to the shock, as well as the physical condition of the person receiving the shock.

GFCIs should be installed in such places as dwellings, hotels, motels, construction sites, marinas, receptacles near swimming pools and hot tubs, underwater lighting, fountains, and other areas in which a person may experience a ground fault.

A GFCI compares the amount of current in the ungrounded (hot) conductor with the amount of current in the neutral conductor. If the current in the neutral conductor becomes less than the current in the hot conductor, a ground fault condition exists.

The missing current is returned to the source by some path other than the intended path (fault current). A fault current as low as 4 mA to 6 mA activates the GFCI and interrupts the circuit.

Once activated, the fault condition is cleared and the GFCI manually resets before power may be restored to the circuit. GFCI protection may be installed at different locations within a circuit.

Direct-wired GFCI receptacles provide a ground fault protection at the point of installation. GFCI receptacles may also be connected to provide GFCI protection at all other receptacles installed downstream on the same circuit. GFCI CBs, when installed in a load center or panelboard, provide GFCI protection and conventional circuit overcurrent protection for all branch-circuit components connected to the CB.

Plug-in GFCls provide ground fault protection for devices plugged into them. Plug-in devices are generally utilized by personnel working with power tools in an area that does not include GFCI receptacles.

HOW GFCI WORKS? THE OPERATING PRINCIPLE OF GFCI

A GFCI compares the amount of current in the ungrounded (hot) conductor with the amount of current in the neutral conductor.

GFCI operation diagram is found below:

ARC FLASH HAZARD ANALYSIS BASICS

To perform an arc flash hazard analysis, you need to start by gathering information on the building’s power distribution system. This data should include the arrangement of components on a one-line drawing with nameplate specifications of every device on the system and the types and sizes of cables.

The local utility company should be contacted so that you can get the minimum and maximum fault currents entering the facility.

Next you will want to perform a short circuit analysis and a coordination study. You will need this information to put into the equations provided in NFPA 70E or the IEEE Standard 1584. These equations will give you the flash protection boundary distances and incident energy potentials you will need to determine your minimum PPE requirements.

In many ways an arc fault analysis is actually a study in risk management. You can be very conservative in your analysis and the results will almost always indicate the need for category 4 PPE.

On the other hand, you can perform the analysis and make adjustments to reduce the arc fault conditions resulting in reduced PPE requirements.

However, use caution when adjusting your calculations. Reducing the bolted fault current can reduce the arc fault current, but it can actually result in a worse situation.

For example, if you reduce the current applied to a motor from 4000 to 1800 A, the arc fault energy is increased from 0.6 to 78.8 cal/cm2. This is the exact opposite outcome that you might expect to achieve before doing the math.

Keep in mind that you are risking OSHA violations and fines if you choose nominal compliance. On the other hand, you can actually be increasing the risk of injury if you force workers to unnecessarily wear cumbersome PPE.

This can also result in little or no high voltage maintenance being performed, which will eventually compromise safety and proper equipment operation. It might prove beneficial to get a registered professional engineering firm to perform arc flash hazard calculations on your behalf and have them recommend appropriate actions and the lowest appropriate category of PPE.

TOP 5 HAZARD OF HAND TOOLS IN CONSTRUCTION AND ELECTRICAL WORKS

What are the Hazards of Hand Tools?

Employees should be trained in the proper use and handling of tools and equipment. The greatest hazards posed by hand tools result from misuse and improper maintenance.
Some examples include:

• Using a chisel as a screwdriver, the tip of the chisel may break and fly off, hitting the user or other employees.

• If a wooden handle on a tool is loose, splintered, or cracked, the head of the tool may fly off and strike the
user or other employees.

• If the jaws of a wrench are sprung, the wrench might slip.

• If impact tools such as chisels, wedges, or drift pins have mushroomed heads, the heads might shatter on impact, sending sharp fragments flying toward the user or other employees.

• When working in close proximity, employees should target saw blades, knives, or other tools away from away aisle areas and other employees. Knives and scissors must be sharp; dull tools can cause more hazards than sharp ones. Cracked saw blades must be removed from service.

Wrenches must not be used when jaws are sprung to the point that slippage occurs. Impact tools such as drift pins, wedges, and chisels must be kept free of mushroomed heads.

Iron or steel hand tools may produce sparks that can be an ignition source around flammable substances. Where this hazard exists, spark-resistant tools made of non-ferrous materials should be used where flammable gases, highly volatile liquids, and other explosive substances are stored or used.