Definitions for electric power

Under 1926.968, an "attendant" is an employee assigned to remain immediately outside the entrance to an enclosed or other space to render assistance as needed to employees inside the space.

• This means the attendant’s role is to stay right outside the entry (for example, a manhole or vault) and be available to help entrants in an emergency or to provide immediate assistance.
• See the definition of “Attendant” in 1926.968 for the full text.

Under 1926.968, an "automatic circuit recloser" is a self-controlled device that automatically interrupts and then recloses an alternating-current circuit following a predetermined sequence of openings and reclosings, and that then either resets, holds closed, or locks out.

• These devices are used to automatically restore power after momentary faults but may lock out for persistent faults.
• See the definition of “Automatic circuit recloser” in 1926.968.

Under 1926.968, a "barricade" is a physical obstruction (like tape, cones, or A-frame structures) that warns about and limits access to a hazardous area, while a "barrier" is a physical obstruction that prevents contact with energized lines or equipment or prevents unauthorized access to a work area.

• Put simply, barricades provide warning and limit access; barriers physically prevent contact or access to energized parts.
• See the definitions of “Barricade” and “Barrier” in 1926.968.

Under 1926.968, a "bond" is the electrical interconnection of conductive parts designed to maintain a common electric potential.

• Bonding reduces voltage differences between conductive parts so they don't become a shock hazard if energized.
• See the definition of “Bond” in 1926.968.

Under 1926.968, a "bus" is a conductor or group of conductors that serve as a common connection for two or more circuits.

• Buses are often found in switchgear and distribution panels where multiple circuits connect to the same conductor assembly.
• See the definition of “Bus” in 1926.968.

Under 1926.968, a "bushing" is an insulating structure that includes a through conductor or provides a passageway for such a conductor, and when mounted on a barrier, insulates the conductor from the barrier so current can pass from one side to the other.

• In practice this is the insulated sleeve or insert where a conductor passes through a grounded transformer tank, switchgear, or enclosure.
• See the definition of “Bushing” in 1926.968.

Under 1926.968, a "cable" is a conductor with insulation (or a stranded conductor) with or without coverings (single-conductor cable), or a combination of conductors insulated from one another (multiple-conductor cable). A "cable sheath" is a conductive protective covering applied to cables.

• The note to "cable sheath" explains that a sheath may consist of multiple layers, one or more of which may be conductive — so the outer construction can include both conductive and nonconductive layers.
• See the definitions of “Cable” and “Cable sheath” in 1926.968.

Under 1926.968, a "circuit" is a conductor or system of conductors through which an electric current is intended to flow.

• That includes anything from a single wire to a complex set of interconnected conductors designed to deliver power.
• See the definition of “Circuit” in 1926.968.

Under 1926.968, "clearance (between objects)" means the clear surface-to-surface distance between two objects, while "clearance (for work)" refers to authorization to perform specified work or permission to enter a restricted area.

• "Clearance (between objects)" is a physical spacing measure used to assess shock and flash protection.
• "Clearance (for work)" is an administrative authorization (permission) that lets a worker enter or perform tasks in a restricted or potentially hazardous area.
• See the definitions of “Clearance (between objects)” and “Clearance (for work)” in 1926.968.

Under 1926.968, a "conductor" is a material, usually in the form of a wire, cable, or bus bar, used for carrying an electric current.

• The term covers both insulated and bare conductors used to carry electricity in transmission and distribution systems.
• See the definition of “Conductor” in 1926.968.

Under 1926.968, a "contract employer" is an employer, other than the host employer, that performs work covered by Subpart V under contract.

• This identifies responsibilities when multiple employers (host and contractors) work on the same electric power installation.
• See the definition of “Contract employer” in 1926.968.

Under 1926.968, a "covered conductor" is a conductor covered with a dielectric that has no rated insulating strength or has a rated insulating strength less than the circuit voltage in which it is used.

• In practice, covered conductors offer limited protection and cannot be treated as fully insulated for higher-voltage systems.
• See the definition of “Covered conductor” in 1926.968.

Under 1926.968, "deenergized" means free from any electrical connection to a source of potential difference and from electric charge; not having a potential that is different from earth. The note states that this term applies only to current-carrying parts that are sometimes energized (alive).

• That means parts that are not intended or expected to be energized are not described by this definition for Subpart V purposes.
• See the definition and note for “Deenergized” in 1926.968.

Under 1926.968, a "designated employee (designated person)" is an employee assigned by the employer to perform specific duties under Subpart V who has sufficient knowledge of the equipment, its construction and operation, and the hazards involved to perform those duties safely.

• The employer must ensure the person has the necessary knowledge and assignment in writing or by clear assignment of duties.
• See the definition of “Designated employee (designated person)” in 1926.968.

Under 1926.968, an "enclosed space" is a working space (such as a manhole, vault, tunnel, or shaft) that has limited means of egress or entry, is designed for periodic employee entry under normal operating conditions, and under normal conditions does not contain a hazardous atmosphere though it may under abnormal conditions. OSHA does not consider spaces that are enclosed but not designed for employee entry under normal conditions to be "enclosed spaces" for the purposes of this subpart.

• Spaces that are enclosed and expected to contain a hazardous atmosphere meet the definition of permit spaces under Subpart AA and must follow those entry requirements (see 1926.953 and 1926.1201).
• See the definition of “Enclosed space” in 1926.968 and the cross-references to 1926.953 and 1926.1201.

Under 1926.968, "energized (alive, live)" means electrically connected to a source of potential difference, or electrically charged so as to have a potential significantly different from that of earth in the vicinity.

• This is the practical definition used to determine when parts are considered hazardous due to voltage potential.
• See the definition of “Energized (alive, live)” in 1926.968.

Under 1926.968, a "hazardous atmosphere" includes conditions that may expose employees to death, incapacitation, impairment of self-rescue, injury, or acute illness from causes such as flammable gas/vapor above 10% LFL, airborne combustible dust at or above its LFL, oxygen concentration below 19.5% or above 23.5%, or concentrations of substances that exceed dose or permissible exposure limits in Subpart D or Z. When OSHA has not published a dose or PEL for an air contaminant, employers can use other sources such as Safety Data Sheets that comply with the Hazard Communication Standard, 1910.1200, published guidance, and internal documents to establish acceptable atmospheric conditions.

• The standard also notes that concentrations not capable of causing serious health effects are not covered by this provision.
• See the definition of “Hazardous atmosphere” in 1926.968 and the cross-reference to 1910.1200 for SDS guidance.

Under 1926.968, "guarded" means covered, fenced, enclosed, or otherwise protected by suitable covers, casings, barrier rails, screens, mats, or platforms designed to minimize dangerous approach or inadvertent contact under normal conditions. The note clarifies that wires that are insulated but not otherwise protected are not considered "guarded."

• Thus, insulated conductors still need appropriate guarding measures where inadvertent contact or dangerous approach is possible.
• See the definition and note for “Guarded” in 1926.968.

Under 1926.968, a "qualified employee (qualified person)" is someone knowledgeable in the construction and operation of the electric power equipment involved and of the associated hazards. Note 1 says the employee must have the training required by 1926.950(b)(2) to be considered qualified. Note 2 explains that, except under 1926.954(b)(3)(iii), an employee undergoing on-the-job training who has demonstrated ability and is under direct supervision of a qualified person is considered qualified for the duties they perform.

• In short: formal training per 1926.950(b)(2) is required; on-the-job trainees may be treated as qualified for limited duties while directly supervised (with a specific exception noted in 1926.954(b)(3)(iii)).
• See the definition of “Qualified employee (qualified person)” in 1926.968, 1926.950(b)(2), and 1926.954(b)(3)(iii).

Under 1926.968, "minimum approach distance" is the closest distance an employee may approach an energized or a grounded object. Paragraph (c)(1)(i) of 1926.960 specifically requires employers to establish minimum approach distances.

• Employers must set and enforce these distances to protect workers from electrical shock or arc flash hazards.
• See the definition of “Minimum approach distance” in 1926.968 and the requirement at 1926.960(c)(1)(i).

Under 1926.968, a "manhole" is a subsurface enclosure that personnel may enter and that is used for installing, operating, and maintaining submersible equipment or cable. A "vault" is an enclosure, above or below ground, that personnel may enter and that is used for installing, operating, or maintaining equipment or cable.

• The practical difference is that manholes are typically subsurface and accessed from ground level, while vaults may be above or below ground; both are spaces designed for worker entry and equipment access.
• See the definitions of “Manhole” and “Vault” in 1926.968.

Under 1926.968, "insulated" means separated from other conducting surfaces by a dielectric (including air space) offering high resistance to current passage. The note adds that when an object is said to be insulated, it is understood to be insulated for the conditions to which it is normally subjected; otherwise, it is considered uninsulated for the purposes of this subpart.

• That means insulation is judged in the context of normal use conditions — if conditions change (e.g., damage, moisture), the object may no longer be treated as insulated.
• See the definition and note for “Insulated” in 1926.968.

Under 1926.968, "line-clearance tree trimming" distances are: for voltages to ground of 50 kilovolts or less — 3.05 meters (10 feet); for voltages to ground of more than 50 kilovolts — 3.05 meters (10 feet) plus 0.10 meters (4 inches) for every 10 kilovolts over 50 kilovolts.

• For example, at 69 kV to ground, the required distance would be 10 feet plus 4 inches (for the additional 19 kV over 50 kV scaled per 10 kV increments).
• See the definition of “Line-clearance tree trimming” in 1926.968.

Under 1926.968, a "host employer" is an employer that operates, or controls the operating procedures for, an electric power generation, transmission, or distribution installation on which a contract employer is performing work covered by Subpart V. The note clarifies how OSHA determines who is the host employer and that there will be no more than one host employer.

• If the electric utility or owner operates or controls procedures, OSHA treats them as the host employer; if not, OSHA treats the employer contracted to operate/control as the host employer.
• See the definition and note for “Host employer” in 1926.968.

Under 1926.968, "immediately dangerous to life or health (IDLH)" means any condition that poses an immediate or delayed threat to life, would cause irreversible adverse health effects, or would interfere with escape unaided from a permit space. The note explains that some materials can cause transient effects followed by delayed fatal collapse (e.g., hydrogen fluoride gas), and such materials in hazardous quantities are considered IDLH.

• This definition is critical for selecting respirators, rescue procedures, and determining entry controls in enclosed or permit spaces.
• See the definition of “Immediately dangerous to life or health (IDLH)” in 1926.968.

Under 1926.968, "voltage" is the effective (root mean square, or rms) potential difference between any two conductors or between a conductor and ground. The subpart expresses voltages in nominal values unless otherwise indicated; nominal voltage is the value assigned for convenient designation and the operating voltage may vary above or below that value.

• This means when the standard refers to voltage classes (e.g., 50 kV), it uses nominal voltages for classification, recognizing some operational variation.
• See the definition and note for “Voltage” in 1926.968.

Under 1926.968, the note to "guarded" explicitly states that wires that are insulated but not otherwise protected are not considered "guarded," which means employers cannot assume insulation alone meets the standard's guarding requirement where additional protection (covers, barriers, mats, etc.) is needed.

• Employers should provide appropriate guarding (barriers, covers, or other protective systems) in addition to insulation when the hazard of dangerous approach or inadvertent contact exists.
• See the note to the definition of “Guarded” in 1926.968.