CASE STUDY 3 : ELECTRICAL SAFETY

ELECTRICAL SAFETY

The Defective Insulation Hazard

INTRODUCTION

he purpose of this Electrical Safe Work Practice Training Program is to review basic properties of electricity and to provide guidance concerning proper personal protective equipment and techniques for working on electrical systems.

IMPROPER GROUNDING HAZARD

A damaged live power tool that is not grounded or double-insulated is very dangerous! When an electrical system is not grounded properly, a hazard exists. The most common OSHA electrical violation is improperly of equipment and circuitry.

IMPROPER GROUNDING

OVERLOADS HAZARD

Overloads in an electrical system are hazardous because they can produce heat or arcing. Wires and other components in an electrical system or circuit have a maximum amount of current they can carry safely. If too many devices are plugged into a circuit, the electrical current will heat the wires to a very high temperature. If any one tool uses too much current, the wires will heat up.

Overload plug in

Overload Plug in

WETS CONDITIONS HAZARD

Working in wet conditions is hazardous because you may become an easy path for electrical current. If you touch a live wire or other electrical component and you are well-grounded because you are standing in even a small puddle of water you will receive a shock.

Damaged insulation, equipment, or tools can expose you to live electrical parts. A damaged tool may not be grounded properly, so the housing of the tool may be energized, causing you to receive a shock. Improperly grounded metal switch plates and ceiling lights are especially hazardous in wet conditions. If you touch a live electrical component with an uninsulated hand tool, you are more likely to receive a shock when standing in water.

Wet Condition floor during wiring

Preventive Measures in Electrical Safety

PROTECTION FROM DIRECT CONTACT

A direct contact refers to a person coming into contact with a conductor which is live in normal circumstances 

IEC 61140 standard has renamed protection against direct contact” with the term “basic protection”

DIRECT CONTACT

PROTECTION FROM INDIRECT CONTACT

An indirect contact refers to a person coming into contact with an exposed-conductive-part which is not normally alive, but has become alive accidentally (due to insulation failure or some other cause).The fault current raise the exposed-conductive-part to a voltage liable to be hazardous which could be at the origin of a touch current through a person coming into contact with this exposed-conductive-part

IEC 61140 standard has renamed “protection against indirect contact” with the term “fault protection”.

INDIRECT CONTACT

TO CREATE SAFE  WORKING ENVIROMENT

LOCK OUT AND TAG OUT CIRCUIT AND EQUIPMENT

LOCK AND TAG OUT is a safety procedure which is used in industry and research settings to ensure that dangerous machines are properly shut off and not able to be started up again prior to the completion of maintenance or servicing work.

 It requires that hazardous energy sources be isolated and rendered inoperative before work is started on the equipment in question. The isolated power sources are then locked and a tag is placed on the lock identifying the worker who has placed it. 

The worker then holds the key for the lock ensuring that only he or she can remove the lock and start the machine. This prevents accidental startup of a machine while it is in a hazardous state or while a worker is in direct contact with it.

TAG OUT

OVERLOAD WIRING BY USING  THE RIGHT SIZE OF WIRE

Control Hazards of Flexible Wiring

Use flexible wiring properly

Electrical cords supplement fixed wiring by providing the flexibility required for maintenance, portability, isolation from vibration, and emergency and temporary power needs.

Flexible wire

Use The Right extension cord

The size of wire in an extension cord must be compatible with the amount of current the cord will be expected to carry.

The amount of current depends on the equipment plugged into the extension cord. 

Current ratings (how much current a device needs to operate) are often printed on the nameplate.

Extention cord

WHAT WILL HAPPEN IF WE NOT CONTROL ELECTRICAL SAFETY?

-It will cause of death during do the maintaince 

-The wire may peel of during cutting  and cause the electric shock 

- Shock circuit will happen

- Will make more cost to renew the wiring 

- Can damage the electrical equipment

- Can cause the explode to the disturbition box

- Can burn the house

CONCLUSION

The control of electrical hazards is an important part of every safety and health program. The measures suggested in this booklet should be of help in establishing such a program of control. 

The responsibility for this program should be delegated to individuals who have a complete knowledge of electricity, electrical work practices, and the appropriate OSHA standards for installation and performance.

Everyone has the right to work in a safe environment. Through cooperative efforts, employers and employees can learn to identify and eliminate or control electrical hazards.

GROUP DISCUSSION

INTRODUCTION

The term ‘Engineering Controls’ covers a broad spectrum of possible interventions that are intended to reduce worker exposure, to chemical, physical and biological agents. This article will explain what ‘Engineering Controls’ are with respect to chemical and biological agents and how they fit into the hierarchy of controls. Examples are given of engineering controls along with some advantages and limitations. The importance of matching the control measure to the health risk and its reliability is also discussed along with commissioning. Once control has been achieved the article will explain why maintenance and checks are vital in order to maintain good control and therefore reduce worker exposure.

Definition

In the context of health and safety, an ‘Engineering Control’ can be described as a physical modification to a process, or process equipment, or the installation of further equipment with the goal of preventing the release of contaminants into the workplace. As can be seen from this broad definition there are a wide range of engineering controls, which could be applied. The control selected will depend upon the type of process, the nature of the contaminant source (its toxicity and release mechanism) and the route of exposure (inhalation, dermal, and ingestion). However, the reality is that no single engineering control in isolation will be successful; control is always a mixture of equipment and ways of working.

The Hierarchy of Control

The approach to controlling the chemical risk released from a process is rarely straightforward as there will always be a choice of control options – some easier to apply than others. However, the approach taken should be based on a priority list. This principal of priority is often referred to as the ‘Hierarchy of Control’. The European Control Hierarchy, as stipulated by Council Directive 98/24/EC gives the priority order and is summarised below

1. Elimination of hazardous substances
2. Substitution by a substance less hazardous 
3. Design of appropriate work processes and engineering controls and use of adequate equipment and materials, so as to avoid or minimise the release of hazardous chemical agents which may present a risk to workers' safety and health at the place of work
4. Application of collective protection measures at the source of the risk, such as adequate ventilation and appropriate organisational measures
5. Where exposure cannot be prevented by other means, the application of individual protection measures including personal protective equipment (PPE).

The directive goes on to state that hazardous chemical agents shall be eliminated or reduced to a minimum by

• the design and organisation of systems of work at the workplace
• the provision of suitable equipment for work with chemical agents and maintenance procedures which ensure the health and safety of workers at work
• reducing to a minimum the number of workers exposed or likely to be exposed
• reducing to a minimum the duration and intensity of exposure
• appropriate hygiene measures
• educing the quantity of chemical agents present at the workplace to the minimum required for the type of work concerned

 It should be noted that this hierarchical approach is not unique to Europe and is adopted by safety professionals worldwide. From the above list it can be seen that engineering controls are integrated into steps 1 to 4. For example it can be argued that modifying a manufacturing process so as to eliminate the hazardous substance is a form of engineering control. However, it is common practice to associate engineering controls with steps 3 and 4: i.e. once elimination and substitution of chemical hazards have been considered. At times engineering controls may not offer adequate control and may need to be supplemented with other measures. Often this will take the form of PPE, which includes respiratory protection equipment (RPE). As can been seen from the priority list, PPE is the last step if all other interventions fail to offer sufficient protection. The problem with PPE is that it only protects the wearer. For RPE this is of particular concern as whilst the process operator may be protected from an airborne hazard, once it is released into the air it will inevitably pervade the workplace and therefore expose others who are likely to be unprotected. Furthermore for RPE to be effective it needs to be properly selected and correctly fitted, making training and user cooperation essential.

Types and Examples of Engineering Controls

Process/Exposure source	Engineering control	Additional procedural control
Cleaning with solvent on rag	·        Use a rag holder ·         Provide a small bin with a lid for used rags.	·         Check controls are used ·         (ii) Safe disposal of waste
Dust spills from damaged sacks	·         Portable vacuum cleaners with HEPA filter	·         Ensure vacuum is maintained and available for use ·         Safe emptying of vacuum cleaner
Cutting-fluid mist from a lathe	·         Put an enclosure around the lathe and extract and filter the air and discharge to a safe place (Protective gloves will also be required)	·         Check and maintain fluid quality ·         Test and maintain controls
Dust from disc cutter on stone worktop	·         Carry out the process in an enclosure fitted with extraction, filter and extract to a safe place	·         Test and maintain controls ·         Train workers
Transfer of volatile liquids	·         Pumping rather than pouring ·         Tight fitting lids to minimise evaporation	·         Regular checks and maintenance (e.g. Check for damage to lids seals)
Evaporation of liquid from an electroplating tank	·         A layer of plastic balls floating on the surface to reduce both evaporation and mists	·         Check and maintain controls

Ensuring that Engineering Controls are effective and reliable

Why engineering controls often fail to protect workers

Engineering controls can fail for a variety of reasons. Often they are not as effective as envisaged and therefore fail to protect from the date they are installed. Even when initially effective their performance can gradually decline. This can be exacerbated by poor management, e.g. inadequate training. Therefore there are issues to consider in ensuring controls work effectively and go on working.

Commissioning

Once a control measure is designed and installed it needs to be commissioned. ‘Commissioning’ is proving that the engineering control is capable of providing adequate exposure control. The type of commissioning and the complexity depends upon the control measure. Probably the most complex commissioning process is that of LEV systems. Unfortunately LEV commissioning is frequently carried out incompletely or is inadequate. LEV commissioning tends to focus on the engineering parameters, such as system pressures and air velocities. Whilst this is an essential part of the commissioning process, a judgement on the effectiveness of the controls and the worker exposure needs to be taken. There are a number of qualitative and quantitative tools available to help the assessor judge control. An example of a qualitative assessment is the use of smoke tubes to visualise the air flow in and around an LEV hood in order to assess LEV performance. An example of a quantitative control is personal sampling to quantify worker exposure to a particular substance(s).

Worker Training

In isolation, an engineering control solution is destined to fail. They need to be integrated with other control measures, such as a ‘standard operating procedure’. It is highly likely that some form of training and supervision will also be required to ensure that the controls are correctly used and therefore control workers’ exposure.

Checks, Monitoring and Maintenance

Without regular checks and routine maintenance, the effectiveness of engineering controls will degrade gradually and inevitably fail. The time it takes for this to occur will depend upon the type of control measure. Engineering controls tend to degrade slowly with time and this often goes unnoticed. An example of this are poorly maintained LEV systems; often the workers can hear the fan impeller rotating, but do not realise that the volume flow rate of the system is imperceptibly falling with time resulting in a loss of control of the airborne contaminant. In this example the performance of the LEV hood could be continually monitored by the use of an air flow indicator, such as a pressure gauge.

Conclusion

All too often when companies realise they have an exposure problem, they immediately assume PPE is the only solution. Invariably this is not the case, and following the hierarchy of controls, engineering controls that are properly commissioned and maintained play an important role in reducing the workers exposure to the chemical risk in the workplace.

References

https://oshwiki.eu/wiki/Engineering_controls#Designing_and_Implementing_Engineering_Controls