OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 18 Personal Protective Equipment

Section 232 Flame resistant clothing

Flash fires and explosions are common hazards at a variety of Alberta workplaces. These hazards are present in work areas where flammable materials are present, handled, processed, or stored. In the petrochemical industry, for example, flash fires can occur at well head sites, collection points, compressor stations, refineries, and petrochemical and plastics plants. In such areas, the potential exists for developing an explosive atmosphere capable of injuring or killing workers and causing extensive property damage.

Industrial flash fires and explosions result from the accidental release and ignition of flammable fuels or chemicals. The size and duration of the flame that results from this ignition is determined by the amount of fuel available, the efficiency of combustion, and the environmental and physical characteristics of the site of the flash fire or explosion. The temperatures attained by flash fires have been estimated to range from 550 to 1050°C, although higher temperatures are believed to occur. Even the lowest estimated temperature exceeds the temperature at which most regular clothing fabrics burst into flames.

If a worker may be exposed to a flash fire or electrical equipment flashover, the employer must ensure that the worker wears flame resistant outerwear and uses other protective equipment appropriate to the hazard. The employer is not required to pay for and provide flame resistant outerwear. However, the employer is required to ensure that a worker wears this equipment if there is a danger of a flash fire or flashover.

Commentary about clothing and PPE for arc flash protection

Readers will note that while this section requires workers to wear and use appropriate flame resistant (FR) outerwear and other PPE for protection against arc flash events, the section does not specify compliance with a particular standard or standards. In particular, CSA Standard Z462-08, Workplace electrical safety, is not referenced.

CSA Standard Z462, which is based on a similar U.S. Standard NFPA 70E, Standard for Electrical Safety in the Workplace, was published at the end of December, 2008. As such, it was published after most of the requirements of the 2009 edition of the OHS Code were finalized. Furthermore, Workplace Health and Safety did not receive any requests from industry to reference the standard during the time that the standard and the OHS Code were being prepared.

Despite the fact that CSA Standard Z462 is not referenced in the OHS Code, this section does require that an employer ensure that workers who may be exposed to an arc flash wear FR outerwear and use other PPE appropriate to the hazard. In determining the rating of the outerwear and which PPE is appropriate, some employers are using Z462 as a source of guidance information. Readers need to recall that FR clothing and other arc flash PPE are only required if the equipment being worked on is energized. If the equipment is isolated and de-energized, this safety equipment is unnecessary.

It has come to the attention of Workplace Health and Safety that for some employers, Z462 is becoming the standard of choice, an industry best practice. As a consequence, other employers may feel that they have an obligation to follow the standard as an indication of their being duly diligent. If it is used, employers should review the scope of Z462 to ensure that the standard is applied correctly.

An employer can chose to use Z462 for guidance, or any other standard or information source that the employer considers appropriate; a listing of other standards relevant to arc flash protection are shown below. The OHS Code does not specify which standard or information source the employer must use.

For more information
ASTM Standard F1506-08, Standard Performance Specification for Textile Material for Wearing Apparel for Use by Electrical Workers Exposed to Momentary Electric Arc and Related Thermal Hazards
ASTM Standard F1891-06, Standard Specification for Arc and Flame Resistant Rainwear
CSA Standard Z462-08, Workplace Electrical Safety

ULC Standard CAN/ULC-61482-1-06, Live working – Flame resistant materials for clothing for thermal protection of workers – Thermal hazards of an electrical arc – Part 1: Test methods
IEC Standard 61482-1-1: 2009, Protective clothing against the thermal hazards of an electrical arc – Part 1 – 1: Test methods – Method 1: Determination of the arc rating (APV or EBT50) of flame resistant materials for clothing
IEC Standard 61482-2: 2009, Live working – Protective clothing against the thermal hazards of an electric arc – Part 2: Requirements

Subsection 232(2)

Workers who have survived flash fires and explosions and were not wearing flame resistant outerwear have suffered terribly painful and disfiguring burns. However, in general, they do not suffer the most serious burns on their uncovered head and hands. Instead, the areas that are covered by their regular clothing and not protected by flame resistant outerwear are the most severely burned. The burning clothing, in contact with the skin and burning long after the flame has retreated, causes the most severe burns. Clothing that melts without burning can also cause significant damage as it must often be peeled away from the damaged skin and tissues that remain beneath the melted clothing.

To reduce the possibility of clothing melting to the skin or burning, the clothing workers wear beneath their flame resistant outerwear must be made of flame resistant fabrics or natural fibres. Examples of appropriate natural fibres include wool, cotton, and silk. The worker is responsible for ensuring this is done. Readers should refer to the manufacturer’s specifications that accompany the flame resistant outerwear for more information.

For more information
Appropriate Workwear for Flash Fire and Explosion Hazards
Bulletin PPE005
CGSB Standard CAN/CGSB-155.20-2000 Workwear for Protection Against Hydrocarbon Flash Fire, Canadian General Standards Board (CGSB)
CGSB Standard CAN/CGSB-155.21-2000 Recommended Practices for the Provision and Use of Workwear for Protection Against Hydrocarbon Flash Fire, Canadian General Standards Board (CGSB)