What is an arc flash?
An arc flash is an electrical fault that can release fatal amounts of energy in the form of pressure, heat, sound, and molten metal.
What causes an arc flash?
An electrical arc flash can be caused by any combination of the following:
- Accidental contact of two or more phases
- Accidental contact on one or more phases and ground
- Current overload
- Mechanical failure
What needs to be analyzed?
The National Electrical Code (NEC) states the following:
“Electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers, that are in other than dwelling occupancies and are likely to require examination, adjustment, servicing, or maintenance while energized.”
The Occupational Safety and Health Administration (OSHA) is more general and states the following for employers operating generation, transmission, and/or distribution facilities:
“Paragraph (l)(8) of 1920.269 addresses protecting employees from flames and electric arcs. This paragraph requires employers to: (1) Assess the workplace for flame and electric-arc hazards; (2) estimate the available heat energy from electric arcs to which employees would be exposed…” “OSHA will consider an employee exposed to electric-arc hazards if there is a reasonable likelihood that an electric arc will occur in the employee’s work area, in other words, if the probability of such an event is higher than it is for the normal operation of enclosed equipment.”
Since the turn of the century, employers have become more aware of the major cause of electrical accidents – arc flash. According to the NFPA 70E more than 2,000 people are admitted to burn centers with severe arc flash burns each year. The majority of hospital admissions due to electrical accidents are from arc flash burns, not from shock. As a result, major organizations have refined their standards to better protect electrical workers from arc flash hazards. They also require an arc flash analysis be performed to determine potential exposure to an electric arc for employees who work on or near energized parts or equipment. Aside from the regulatory requirements, a thorough review and analysis is prudent for the wellbeing of all those working in and around energized electrical equipment.