What Does Working Distance Mean?
Working distance refers to the minimum distance between a worker and a particular hazard.
Most commonly, this refers to an arc flash (electrical hazard), but it may also refer to other hazards such as a radiation-emitting hazard. The term is used by occupational health and safety experts to help workers understand how much risk they are exposed to at a given distance from a particular hazard.
Safeopedia Explains Working Distance
Standards bodies such as the National Fire Protection Association (NFPA) often subdivide different risks associated with a hazard into separate categories that are demarcated by a minimum and maximum working distance from the hazard. This allows the organization to prescribe risk-mitigation requirements, such as the use of specific personal protective equipment (PPE), in an easy-to-understand manner. Occupational health and safety regulatory agencies, such as OSHA, also have requirements for workers to maintain a minimum safe working distance from certain hazards.
The working distance concept is most consistently used with specific reference to the distance between a worker and an electrical hazard as a way of calculating the maximum arc-flash risk that a worker will be exposed to. The minimum working distance between a worker and a hazard is the position at which the worker faces the greatest amount of risk, as it is the position within the working area at which the potential incident energy from an arc flash would be the greatest.
OSHA requires that workers who trim trees from power and telecommunication lines must maintain specific acceptable minimum working distances from any energized conductors on the line system, and this minimum distance increases as the amount of voltage flowing through the lines increases. The NFPA also uses working distance in its standards for electrical hazards to determine how close individuals are allowed to an electrical hazard and what type of protection they must have at each distance.
The space between a worker and an unprotected ledge or other fall hazard is another distance that is commonly described in working-distance terms. Furthermore, in ergonomics, the distance between a worker’s face and a computer screen may also be defined in working-distance terms. Working distance is also an important concept for individuals working with radiation sources, as the amount of radiation energy a worker is exposed to decreases exponentially based on his or her distance from the source. The use of tools and equipment that limit worker contact with harmful chemicals—for instance, when a sponge roller is used to clean a surface instead of a handheld sponge—is also expressed in terms of working distance by some occupational health and safety agencies, such as the UK Health and Safety Executive (HSE).