Flash Hazard Analysis

Last updated: September 3, 2020

What Does Flash Hazard Analysis Mean?

A flash hazard analysis, more precisely called an arc flash hazard analysis or an arc flash risk assessment, is a type of hazard assessment tool that is designed to measure the risk that personnel working in proximity to electrical equipment could be exposed to an arc flash. An arc flash is an electrical explosion that occurs when a short circuit or electrical fault causes current to flow through the air.

Flash hazard analyses are a technical process that must be undertaken by qualified engineers. As part of the analysis, the engineer must calculate the incident energy (heat) that would be caused by an arc flash, as well as evaluate the probability that an arc flash could occur. Finally, the assessor must provide their client/employer with recommendations for how to reduce the risk posed by their equipment.

Safeopedia Explains Flash Hazard Analysis

In most countries, any facility that has significant electrical equipment (e.g., equipment that generates, transmits, or distributes electricity), must perform a flash hazard analysis. In the US, the use of a flash hazard analysis is legally required by OSHA standard 1910.132 and further mandated by NFPA standard 70e (section 130.5); OSHA largely defers to the latter standard when determining how an employer should meet their electrical safety obligations.

An arc flash hazard assessment has three main goals: First, to determine the arc flash boundary. Second, to determine what protective equipment is necessary for work inside the boundary. Finally, to implement measures to reduce the risk of an arc flash as much as practicable. The arc flash protection boundary is the minimum distance at which the incident energy (heat) produced by an arc flash is equal to 1.2 calories per cm2 (cal/cm2)—the amount of energy necessary to cause second degree burns when in contact with human skin.

Arc flash risk reduction controls take a variety of forms, including replacing or altering machinery to make it safer, and adding equipment to block elements of an arc flash should it occur. Mandatory aspects of the risk reduction process include prescribing the correct PPE for employees, labelling equipment to identify its arc flash rating, and providing employees with safety training.

There is no single method for calculating arc flash energy. In the US, two calculation methods are legally recognized; one described by NFPA 70E, and one described by IEEE 1584. In Canada, CSA standard Z462 (based on NFPA 70E) is used for calculations. Europe lacks a standard for calculations; however, the convention is to use the IEEE 1584 method.


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