Glossary

An absence-of-voltage test is the verification, made with a test instrument rated for the application, that no voltage is present on each conductor or circuit part at the point of work before the part is treated as de-energized; the instrument is proven on a known voltage source before and after the test.

Article 100 of NFPA 70E-2027 defines the arc flash boundary, where an arc flash hazard exists, as the approach limit at which the incident energy equals the threshold value the definition states, the same value clause 130.5(E) uses for the incident energy analysis method.

An arc flash PPE category is a class of arc-rated clothing and accessory protective equipment that the PPE category method assigns to a piece of equipment by its type, voltage class and protection, in place of an incident energy figure from analysis; each category carries a minimum arc rating for the clothing system.

An arc flash risk assessment is the documented process of identifying arc flash hazards, estimating the likelihood of an arc flash occurrence and the severity of the resulting injury, and deciding what additional protective measures, including personal protective equipment, are needed.

Arc rating is the value attributed to an arc-rated material or clothing system that states the incident energy it can be exposed to before the onset of a second-degree burn or breakopen under the fabric and garment test methods; protective clothing for arc flash work is selected so that its arc rating meets or exceeds the estimated incident energy.

Article 100 of NFPA 70E-2027 defines an electrically safe work condition as the state in which the conductor or circuit part has been disconnected from energized parts, locked or tagged under established standards, tested for absence of voltage, and temporarily grounded for personnel protection where necessary; an informational note points to clause 110.2(C) and to clause 120.2 through clause 120.6 for how the state is reached.

An energized electrical work permit is the written authorization an employer issues before work proceeds on or near exposed energized conductors or circuit parts that have not been placed in an electrically safe work condition; it records the justification, the risk assessment results, the protective measures and the approvals.

Incident energy is the thermal energy per unit area that an arc flash delivers to a surface at a stated distance from the arc source; arc flash hazard analysis estimates it at the working distance to set the arc flash boundary and choose the protective clothing, and it is usually expressed in calories per square centimeter or joules per square centimeter.

Article 100 of NFPA 70E-2027 defines the limited approach boundary as an approach limit at a distance from an exposed energized electrical conductor or circuit part inside which a shock hazard exists.

Lockout/tagout is the placement of a lock, a tag or both on an energy-isolating device under a documented procedure so that the circuit cannot be re-energized until each device is removed by the person who installed it; it is the control-of-energy step in establishing an electrically safe work condition.

The first exception to clause 110.2(B) of NFPA 70E-2027 allows normal operation of equipment without an electrically safe work condition only when the equipment is in a normal operating condition, which requires all seven of the following: properly installed, properly maintained, rated for the available fault current, used in accordance with its listing, labeling and manufacturer's instructions, doors closed and secured, all covers in place and secured, and no evidence of impending failure.

Article 100 of NFPA 70E-2027 defines a qualified person as one who has demonstrated skills and knowledge of the construction and operation of electrical equipment and installations and has received safety training to identify the hazards and reduce the associated risk; an unqualified person is anyone who does not meet that definition, and the definition names no credential.

Article 100 of NFPA 70E-2027 defines the restricted approach boundary as an approach limit at a distance from an exposed energized conductor or circuit part inside which the likelihood of electric shock is increased by electrical arc-over combined with inadvertent movement.

Temporary protective grounding is the bonding of de-energized conductors and circuit parts to ground with portable grounding equipment for the duration of the work, so that induced voltage, stored energy or an unintended re-energization is carried to ground and the protective devices operate before the worker is exposed.

Working distance is the distance between the arc source and the face or chest of the worker performing a task, the point at which the incident energy for that task is estimated.