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Conducting a Risk Assessment
There are three essential steps which you should take to make sure that hazards in your workplace are eliminated or controlled:
1. Hazard Identification Methods for identifying hazards in your workplace include:
2. Risk Assessment Once hazards have been identified you need to assess the risk. This is the likelihood of an injury or illness occurring from exposure to the hazard. When assessing risk there are several factors that should be taken into account. These factors include:
For example, the intensity, frequency and duration of exposure to the sun's harmful rays are factors when determining the risk of skin cancer. Severity can be classified as:
The overall purpose of the assessment is to determine priorities in risk control. ^ 3. Risk Control Once the hazard has been assessed control options for eliminating or reducing the risk of exposure to the hazard must be considered. The controls include:
What is a warning? Preventing and Controlling Electrical Hazards 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. Electrical accidents appear to be caused by a combination of three possible factors - unsafe equipment and/or installation, workplaces made unsafe by the environment, and unsafe work practices. There are various ways of protecting people from the hazards caused by electricity. These include: insulation, guarding, grounding, electrical protective devices, and safe work practices. ^Insulation One way to safeguard individuals from electrically energized wires and parts is through insulation. An insulator is any material with high resistance to electric current. Insulators-such as glass, mica, rubber, and plastic-are put on conductors to prevent shock, fires, and short circuits. Before employees prepare to work with electric equipment, it is always a good idea for them to check the insulation before making a connection to a power source to be sure there are no leakages or exposed wires. The insulation of flexible cords, such as extension cords, is particularly vulnerable to damage. Insulation at the points of isolation should also be checked. The insulation should be suitable for the voltage and existing conditions, such as temperature, moisture, oil, gasoline, or corrosive fumes. All these factors must be evaluated before the proper choice of insulation can be made. ^Guarding Live parts of electric equipment operating at 50 volts or more must be guarded against accidental contact. Guarding of live parts may be accomplished by:
Entrances to rooms and other guarded locations containing exposed live parts must be marked with conspicuous warning signs forbidding unqualified persons to enter. Indoor electric wiring more than 415 volts and that is open to unqualified persons must be made with metal-enclosed equipment or enclosed in a vault or area controlled by a lock. In addition, equipment must be marked with appropriate caution signs. ^Grounding Grounding is another method of protecting employees from electric shock; however, it is normally a secondary protective measure. The "ground" refers to a conductive body, usually the earth, and means a conductive connection, whether intentional or accidental, by which an electric circuit or equipment is connected to earth or the ground plane. By "grounding" a tool or electrical system, a low-resistance path to the earth is intentionally created. When properly done, this path offers sufficiently low resistance and has sufficient current carrying capacity to prevent the build-up of voltages that may result in a personnel hazard. This does not guarantee that no one will receive a shock, be injured, or be killed. It will, however, substantially reduce the possibility of such accidents - especially when used in combination with other safety measures discussed in this booklet. There are two kinds of grounds: One of these is called the "service or system ground." In this instance, one wire-called "the neutral conductor" or "grounded conductor" - is grounded at the generator or transformer and again at the service entrance of the building. This type of ground is primarily designed to protect machines, tools, and insulation against damage. To offer enhanced protection to the workers themselves, an additional ground, called the "equipment ground," must be furnished by providing another path from the tool or machine through which the current can flow to the ground. This additional ground safeguards the electric equipment operator in the event that a malfunction causes the metal frame of the tool to become accidentally energized. The resulting heavy surge of current will then activate the circuit protection devices and open the circuit. For protection of workers on de-energized lines short-circuiting and earthing equipment are used. In this case all the conductors of the circuit are shorted and earthed. ^Circuit Protection Devices Circuit protection devices are designed to automatically limit or shut off the flow of electricity in the event of a ground-fault, overload, or short circuit in the wiring system. Fuses, circuit breakers, and ground-fault circuit interrupters are three well-known examples of such devices. Fuses and circuit-breakers are over-current devices that are placed in circuits to monitor the amount of current that the circuit will carry. They automatically open or break the circuit when the amount of current flow becomes excessive and therefore unsafe. Fuses are designed to melt when too much current flows through them. Circuit breakers, on the other hand, are designed to trip open the circuit by electro-mechanical means. Fuses and circuit breakers are intended primarily for the protection of conductors and equipment. They prevent over-heating of wires and components that might otherwise create hazards for operators. They also open the circuit under certain hazardous ground-fault conditions. The ground-fault circuit interrupter, or GFCI, is designed to shutoff electric power within as little as 1/40 of a second. It works by comparing the amount of current going to electric equipment against the amount of current returning from the equipment along the circuit conductors. If the current difference exceeds 6 milliamperes, the GFCI interrupts the current quickly enough to prevent electrocution. The GFCI is used in high-risk areas such as wet locations and construction sites. Umeme employees will be trained in specific hazards associated with their potential exposure. This training will include isolation of energy, hazard identification, connection to supply, distribution installations, clearance distances, and emergency procedures. ^De-energizing Electrical Equipment All electrical parts exceeding 50 volts will be de-energized before an employee works on or near equipment unless:
When any employee is exposed to direct or indirect contact with parts of fixed electrical equipment or circuits which have been de-energized, the electrical energy source will be locked out. The line must be proven dead (de-energized) using appropriate methods. The accidental or unexpected sudden energizing of electrical equipment can cause severe injury or death. Before ANY inspections or repairs are made -- even on the so-called low-voltage circuits-the current must be turned off at the isolation point and the switch padlocked in the OFF position. At the same time, the switch or controls of the machine or other equipment being locked out of service must be securely tagged (labelled) to show which equipment or circuits are being worked on. In case of fuses or links they shall be removed and kept. ^Overhead Lines If work is to be performed near overhead power lines, the lines must be deenergized and grounded by the operator, or other protective measures must be provided before work is started. Protective measures (such as guarding or insulating the lines) must be designed to prevent employees from contacting the lines. ^Mechanical Equipment Near Overhead Power Lines Unqualified employees and mechanical equipment must stay at least 3 metres away from overhead power lines. When mechanical equipment is being operated near over-head lines, employees standing on the ground may not contact the equipment unless it is located so that the required clearance cannot be violated even at the maximum reach of the equipment. ^Personal Protective Equipment Employees whose occupations require them to work directly with electricity must use the personal protective equipment required for the jobs they perform. Examples of Personal Protective Equipment (PPE) which might be needed for protection against electric shock and body abrasion include but are not limited to:
Additionally, other ways of protecting employees from the hazards of electrical shock will be implemented, including insulation and guarding of live parts. The insulation must be appropriate for the voltage and the insulating material must be undamaged, clean, and dry. Guarding prevents the employee from coming too close to energized parts. It can be in the form of a physical barricade or it can be provided by installing the live parts out of reach from the working surface. ^Tools To maximize his or her own safety, an employee should always use tools that work properly. Tools must be inspected before use, and those found questionable, removed from service and properly tagged. Tools and other equipment should be regularly maintained. Inadequate maintenance can cause equipment to deteriorate, resulting in an unsafe condition. *Tools that are used by employees to handle energized conductors must be designed and constructed to withstand the voltages and stresses to which they are exposed.* ^Good Judgment Perhaps the single most successful defence against electrical accidents is the continuous exercising of good judgment or common sense. All employees should be thoroughly familiar with the safety procedures for their particular jobs. When work is performed on electrical equipment, for example, some basic procedures are:
^ Qualified Person Those persons who are permitted to work on or near exposed energized parts and are trained in the applicable electrical safe work practices. Qualified Persons shall, at a minimum, be trained in and familiar with:
Maintenance employees should be qualified electricians who have been well instructed in operational procedures. The maintenance worker should at all times be certain that he or she is not exposing other employees to danger. ^Table I: Approach Distance For Qualified Employees Alternating Current
Direct Current
Portable Equipment All portable electric equipment will be handled in such a manner that will not damage or reduce service life. Flexible cords connected to equipment may not be used for raising or lowering equipment and will not be used if damage to the outer insulation is present. Additionally, visual inspections are required and unauthorized alterations of the grounding protection are not allowed to ensure the safety of employees. Prior to each shift, a visual inspection will be performed for external defects and for possible internal damage. Attachment plugs and receptacles may not be connected or altered in a manner that would prevent proper continuity of the equipment-grounding conductor. In addition, these devices may not be altered to allow the grounding pole of a plug to be inserted into slots intended for connection to the current-carrying conductors. Portable electric equipment and flexible cords used in highly conductive work locations or in job locations where employees are likely to contact water or conductive liquids shall be approved by the manufacturer for those locations. The hazardous locations that employees should be aware of include, wet locations and locations where combustible or flammable atmospheres are present. For wet locations, employees' hands will not be wet when plugging and unplugging energized equipment. Energized plug and receptacle connections will be handled only with protective equipment if the condition could provide a conductive path to the employee's hand (if, for example, a cord connector is wet from being immersed in water). In addition, ground-fault circuit interrupter (GFCI) protection is required for some equipment/locations and is also recommended for use in all wet or highly conductive locations. For combustible/flammable atmospheres, all electric equipment and wiring systems in classified locations must meet installation requirements. ^Conductive Materials and Equipment Conductive materials and equipment (e.g., hand tools) will be handled to prevent contact with exposed energized conductors or circuit parts. Conductive articles of jewellery and clothing (such as watch bands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread, or metal headgear) will not be worn. ^Energized Parts If work must be performed while equipment is energized or if de-energizing is not feasible, additional safety measures will be taken to ensure the safety of the qualified employee and any other persons who may be exposed. Protection from energized parts will be suitable for the type of hazard involved. Exposed energized parts in areas accessible to the public shall be continuously protected by an authorized attendant. In areas not accessible to the public, employees shall be protected from exposed energized parts by the use of signs or tags. In addition to signs or tags, barricades shall be used where necessary to limit access to areas with exposed energized parts. ^Illumination Employees will be provided with adequate light to work on energized/de-energized equipment when the illumination is not adequate. ^Portable Ladders Portable ladders will have nonconductive surfaces if they are used where the employee or the ladder could be exposed to electrical shock hazards. ^Reclosing Circuits If circuits are tripped using a protective device power will not be restored until the reason for the interruption is determined and corrected. Fuses or breakers will not be replaced or reset until it is determined that the circuit is safe to operate. Fuses will not be replaced with higher rated fuses or with makeshift devices to bypass circuit protection as designed. Problems will be identified and promptly repaired by a qualified person. ^Permit-To-Work No person shall perform electrical work without first obtaining an electrical permit. An electrical permit is a legal document for the purpose of:
^ Exclusion from requiring an electrical permit is generally only the electrical work performed in replacing fuses, restoring power supplies, etc, where the replacement/restoration can be made without other modifications being required to the electrical installation. |
