An “arc flash hazard” is defined by the CSA Z462-21 Workplace Electrical Safety as a “dangerous condition associated with the release of energy caused by an electric arc”. An arc flash is a dangerous condition which involves an explosion, and can result in serious injuries, burns, and damage to the lungs, eardrums, and eyes. Arc flashes may also cause death.
These conditions can lead to arc flash:
- accidental contact between two conductors
- wiring errors
- insulation deterioration or failure
- corrosion of equipment
- contamination of the equipment (e.g., dust, moisture)
- animals, tools, or fallen parts that short-circuit the equipment
- poor/lack of maintenance
- workers using improper or non-rated tools
- equipment failures, overload, improper use, human error.
An electrical hazard is considered to be removed when protective measures/controls are put in place at the source (e.g., remove the hazard or de-energize), or along the path (e.g., place electrical insulation or a barrier between the worker and the electrical hazard). Where PPE only is needed for worker protection, an electrical hazard is considered to remain and it is necessary to address safety requirements for other workers in the area.
Electrical work performed on or near electrical transmission or distribution systems must be performed according to the “Electrical Utility Safety Rules” published by the Infrastructure Health and Safety Association. [O. Reg. 213/91, s. 181] Workplaces are required to take every reasonable precaution to prevent hazards from energized electrical equipment, installations and conductors. [O. Reg. 213/91, s. 183]
The above electrical work is performed under the authority of the electrical utility and the electrical work is performed by authorized workers (workers are given formal permission from the owner and employer and they are competent to perform work on and in proximity to electrical transmission and distribution systems). Examples are powerline technicians that are performing approved work methods to install and maintain electrical transmission and distribution systems.
Electrical work outside of the above scope must be performed according to the following requirements.
Electrical tools and equipment must meet industry standards. Examples may include, but not limited to, voltage rated tools, correct categories of diagnostic equipment, multi-meters, proximity testers, amp meters and other diagnostic equipment as required, non-conductive ladders, non-conductive scaffolding, voltage rated gloves, and appropriate arc flash protective equipment and clothing. Workers must be trained in and familiar with the tools, equipment and protective devices including personal protective equipment as defined from regulations and/or standards. Workers must follow documented safe work procedures and practices to make sure that they are protected from electrical hazards associated with the work.
Only the authorized person (authorized by the supervisor in charge of the project) may enter a room or other enclosure that contains exposed energized electrical parts. The entrance to this room or enclosure must be marked with warning signs stating that unauthorized people may not enter. [O. Reg. 213/91, s. 184]
Electrical hazards must be identified, workers shall be protected from the electrical hazards to what they are exposed.
All tools, devices and equipment, including personal protective equipment, that are used for working on or near energized exposed parts of electrical equipment, installations or conductors must be designed, tested, maintained, and used in ways that provide protection to workers. [O. Reg. 213/91, s. 192]
When working on or near exposed energized machinery and other apparatus,
- arc flash, flame resistant clothing and other personal protective equipment (PPE) must provide an adequate level of protection to protect the worker
- the outer layer of clothing must be made of arc flash, flame resistant material
- other clothing worn with arc flash, flame resistant PPE must not contribute to increased worker injury
- PPE used must be manufactured, tested and maintained to current recognized industry standards
- workers shall wear approved eye protection in all circumstances where there is a possibility of an electrical flash or arc.
From the Electrical Utility Safety Rules, s. 113.
Electrical arc flash hazards must be identified. Workers that are exposed to arc flash hazards must be adequately protected from the arc flash hazards. This protection is most commonly achieved through an arc flash hazard risk assessment or the application of task tables from the electrical standards. The risk assessment would include the assessment of the equipment or devices to determine the potential incident energy that may be produced in the case of an electrical incident. Arc flash risk assessments also help establish safe work procedures for the electrical workers when performing electrical tasks. The risk assessments allow the worker to determine the safe approach boundaries for contact and arc flash hazards.
Workers who may be exposed to electrical shocks or burns from flash hazards must be trained to use and wear voltage rated rubber gloves and leather protectors as necessary. Rubber gloves must be worn with adequate leather protectors and cannot be worn inside out. Leather protectors must be visually inspected for damage and adequacy immediately before each use. Inadequate or damaged gloves or protectors should not be used. Workers must be trained in the proper use, care, and storage of rubber gloves and leather protectors. [O. Reg. 213/91, s. 193] Voltage rated rubber gloves shall be used and maintained according to the manufactures recommendations and industry standards as prescribed.
Rubber gloves with leather protectors, arc flash protective clothing and equipment, voltage rated tools and defined shock hazard boundaries are the most common protective equipment and measures used for shock protection. All protective rubber gloves must: [O. Reg. 213/91, s. 193]
- protect the worker against electrical shock and burn, and
- be air tested and visually inspected for damage and adequacy immediately before each use.
Rubber gloves rated for voltages above 5,000 volts AC must be tested and certified that they can withstand the voltages for which they are rated: [O. Reg. 213/91, s. 193]
- at least once every three months, if they are in service, and
- at least once every six months, if they are not in service.
NOTE: Voltage rated gloves must meet approved industry standards. They shall be maintained on intervals as prescribed by the manufacturer or industry standards, in addition to the requirements from provincial regulations. Specific care and maintenance standards can be found within CSA Z462-21 Workplace Electrical Safety or CAN/UL S 801 Electric Utility Workplace Electrical Safety for Generation, Transmission, and Distribution.