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Glossary Arc Flash Safety Training (NFPA 70E)

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Acceptable means that an installation or equipment is acceptable to the Assistant Secretary of Labor and approved within the meaning of 29 CFR 1910 Subpart S: (1) If it is accepted, or certified, or listed, or labeled, or otherwise determined to be safe by a nationally recognized testing laboratory recognized pursuant to § 1910.7; or (2) With respect to an installation or equipment of a kind that no nationally recognized testing laboratory accepts, certifies, lists, labels, or determines to be safe, if it is inspected or tested by another Federal agency, or by a State, municipal, or other local authority responsible for enforcing occupational safety provisions of the National Electrical Code and found in compliance with the provisions of the National Electrical Code as applied in this subpart; or (3) With respect to custom-made equipment or related installations that are designed, fabricated for, and intended for use by a particular customer, if it is determined to be safe for its intended use by its manufacturer on the basis of test data which the employer keeps and makes available for inspection to the Assistant Secretary and his authorized representatives.

Accepted

An installation is "accepted" if it has been inspected and found by a nationally recognized testing laboratory to conform to specified plans or procedures of applicable codes.

Accessible (as applied to Wiring Methods)

Accessible (as applied to wiring methods) means capable of being removed or exposed without damaging the building structure or finish, or not permanently closed in by the structure or finish of the building. (See "concealed" and "exposed.")

Accessible (as applied to Equipment)

Accessible (as applied to equipment) means admitting close approach; not guarded by locked doors, elevation, or other effective means. (See "readily accessible."

Affected Employee

An employee whose job requires him/her to operate or use a machine or equipment on which servicing or maintenance is being performed under lockout or tagout, or whose job requires him/her to work in an area in which such servicing or maintenance is being performed.

Alternating Current

Alternating current is current that reverses direction at a steady rate. You have alternating current coming out of the outlets at your house. The rate at which alternating current reverses is called its frequency.

Ampacity

The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

Appliances

Utilization equipment, generally other than industrial, normally built in standardized sizes or types, that is installed or connected as a unit to perform one or more functions.

Approved

Acceptable to the authority enforcing this subpart. The authority enforcing this subpart is the Assistant Secretary of Labor for Occupational Safety and Health. The definition of "acceptable" indicates what is acceptable to the Assistant Secretary of Labor and therefore approved within the meaning of 29 CFR 1910 Subpart S.

Assistant Secretary

Assistant Secretary means the Assistant Secretary of Labor for Occupational Safety and Health, U.S. Department of Labor, or a designee.

Arc Flash Boundary

According to Article 100 of the NFPA 70E, when an arc flash hazard exists, an approach limit from an arc source at which the incident energy equals 1.2 cal/cm² (5 J/cm²).

Arc Flash PPE Category Method

Assistant Secretary means the Assistant Secretary of Labor for Occupational Safety and Health, U.S. Department of Labor, or a designee.

Arc Flash Boundary

There are four categories of arc flash PPE ranging from 1 through 4. Based on the arc flash risk assessment, a category is selected for personnel protection.

Arcing

The luminous electrical discharge (bright, electrical sparking) through the air that occurs when high voltages exist across a gap between conductors.

Arc Performance Thermal Value (APTV)

The incident energy on a material or a multi-layer system of materials that results in a 50 percent probability that heat transfer through the specimen is predicted to cause the onset of a second-degree skin burn injury based on the Stoll curve.

Armored Cable (Type AC)

A fabricated assembly of insulated conductors in a flexible metallic enclosure.

Askarel

A generic term for a group of non-flammable synthetic, chlorinated hydrocarbons used as electrical insulating media. Askarels of various compositional types are used. The gases produced under arcing conditions, while consisting predominantly of non-combustible hydrogen chloride, can include varying amounts of combustible gases depending upon the askarel type.

Attachment Plug (Plug Cap) (Cap)

A device that, by insertion in a receptacle, establishes a connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle.

Authorized Employee

A person who locks out or tags out machines or equipment in order to perform servicing or maintenance on that machine or equipment. An affected employee becomes an authorized employee when that employee's duties include performing servicing or maintenance covered under this 29 CFR 1910 Subpart S.