OSHA general industry electrical safety study guide
OSHA's electrical rules for general industry are in 29 CFR Part 1910, Subpart S (Electrical). This guide sets out what the rule text states on design safety basics in 1910.303 to 1910.305 (approval and marking, working space, guarding of live parts, grounding, GFCI protection, flexible cords and temporary wiring) and on the safety-related work practices in 1910.331 to 1910.335 (qualified and unqualified persons, training, deenergizing and lockout, overhead lines, portable equipment and protective equipment). Consensus standards are not summarized here. Every point links to the regulation and quotes its exact words.
Approval, examination and marking
Conductors and equipment required or permitted by Subpart S are acceptable only if they are approved, as "approved" is defined in 1910.399. Electric equipment must also be free from recognized hazards that are likely to cause death or serious physical harm to employees, and the rule then lists the considerations used to determine the safety of equipment.
“The conductors and equipment required or permitted by this subpart shall be acceptable only if approved, as defined in § 1910.399. (b) Examination, installation, and use of equipment — (1) Examination. Electric equipment shall be free from recognized hazards that are likely to cause death or serious physical harm to employees. Safety of equipment shall be determined using the following considerations:”
Electric equipment may not be used unless it is marked with the manufacturer's name, trademark or other descriptive marking that identifies the organization responsible for the product, and with other markings giving voltage, current, wattage or other ratings as necessary.
“Electric equipment may not be used unless the following markings have been placed on the equipment: (i) The manufacturer's name, trademark, or other descriptive marking by which the organization responsible for the product may be identified; and (ii) Other markings giving voltage, current, wattage, or other ratings as necessary.”
Each disconnecting means required by Subpart S for motors and appliances must be legibly marked to show its purpose, unless it is located and arranged so the purpose is evident. The same applies to each service, feeder and branch circuit at its disconnecting means or overcurrent device.
“Each disconnecting means required by this subpart for motors and appliances shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident. (2) Services, feeders, and branch circuits. Each service, feeder, and branch circuit, at its disconnecting means or overcurrent device, shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident.”
The rule that disconnecting means required by Subpart S be capable of being locked in the open position (1910.303(f)(4), "Capable of accepting a lock") is on the list in 1910.302 of requirements that apply only to electrical installations and utilization equipment installed after August 13, 2007.
“The following requirements apply only to electrical installations and utilization equipment installed after August 13, 2007: § 1910.303(f)(4)—Disconnecting means and circuits—Capable of accepting a lock”
Working space and guarding
Paragraph 1910.303(g) applies to electric equipment operating at 600 volts, nominal, or less to ground. Sufficient access and working space must be provided and maintained about all such electric equipment to permit ready and safe operation and maintenance.
“This paragraph applies to electric equipment operating at 600 volts, nominal, or less to ground. (1) Space about electric equipment. Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment.”
For equipment operating at 600 volts or less that is likely to need examination, adjustment, servicing or maintenance while energized, the depth of the working space in the direction of access to live parts may not be less than Table S-1 shows, except as required or permitted elsewhere in Subpart S. Distances are measured from the live parts if they are exposed, or from the enclosure front or opening if they are enclosed. Table S-1 lists 3.0 ft (0.9 m) for 0-150 volts to ground under Conditions A, B and C, and for 151-600 volts 3.0 ft (0.9 m) under Condition A, 3.5 ft (1.0 m) under Condition B and 4.0 ft (1.2 m) under Condition C.
“Working space for equipment likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the following dimensions, except as required or permitted elsewhere in this subpart: (A) The depth of the working space in the direction of access to live parts may not be less than indicated in Table S-1. Distances shall be measured from the live parts if they are exposed or from the enclosure front or opening if they are enclosed;”
Note 1 to Table S-1 allows minimum clear distances of 0.7 m (2.5 ft) for installations built before April 16, 1981. In the table the note is marked only on Conditions A and B at 0-150 volts and on Condition A at 151-600 volts.
“1. Minimum clear distances may be 0.7 m (2.5 ft) for installations built before April 16, 1981.”
Note 3 to Table S-1: working space is not required in back of assemblies such as dead-front switchboards or motor control centers where there are no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible from locations other than the back. Where rear access is required to work on deenergized parts on the back of enclosed equipment, a minimum working space of 762 mm (30 in.) horizontally must be provided.
“3. Working space is not required in back of assemblies such as dead-front switchboards or motor control centers where there are no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible from locations other than the back. Where rear access is required to work on deenergized parts on the back of enclosed equipment, a minimum working space of 762 mm (30 in.) horizontally shall be provided.”
For that same equipment (likely to need examination, adjustment, servicing or maintenance while energized), the width of the working space in front of it must be the width of the equipment or 762 mm (30 in.), whichever is greater, and the space must always permit at least a 90-degree opening of equipment doors or hinged panels.
“The width of working space in front of the electric equipment shall be the width of the equipment or 762 mm (30 in.), whichever is greater. In all cases, the working space shall permit at least a 90-degree opening of equipment doors or hinged panels”
Required working space may not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, working space in a passageway or general open space must be suitably guarded.
“Working space required by this standard may not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.”
Minimum headroom of working spaces about service equipment, switchboards, panelboards or motor control centers is 1.91 m (6.25 ft) for installations built before August 13, 2007, and 1.98 m (6.5 ft) for installations built on or after that date; for those newer installations, where the equipment is taller than 1.98 m (6.5 ft), the headroom may not be less than the height of the equipment.
“The minimum headroom of working spaces about service equipment, switchboards, panelboards, or motor control centers shall be as follows: (A) For installations built before August 13, 2007, 1.91 m (6.25 ft); and (B) For installations built on or after August 13, 2007, 1.98 m (6.5 ft), except that where the electrical equipment exceeds 1.98 m (6.5 ft) in height, the minimum headroom may not be less than the height of the equipment.”
Except as elsewhere required or permitted by the standard, live parts of electric equipment operating at 50 volts or more must be guarded against accidental contact by approved cabinets or other approved enclosures, or by one of the means the rule lists. The first listed means is location in a room, vault or similar enclosure that is accessible only to qualified persons.
“Except as elsewhere required or permitted by this standard, live parts of electric equipment operating at 50 volts or more shall be guarded against accidental contact by use of approved cabinets or other forms of approved enclosures or by any of the following means: (A) By location in a room, vault, or similar enclosure that is accessible only to qualified persons;”
Two other listed means of guarding those live parts are placement on a suitable balcony, gallery or platform elevated and located to prevent access by unqualified persons, and elevation of 2.44 m (8.0 ft) or more above the floor or other working surface.
“By placement on a suitable balcony, gallery, or platform so elevated and otherwise located as to prevent access by unqualified persons; or (D) By elevation of 2.44 m (8.0 ft) or more above the floor or other working surface.”
Entrances to rooms and other guarded locations containing exposed live parts must be marked with conspicuous warning signs forbidding unqualified persons to enter.
“Entrances to rooms and other guarded locations containing exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter.”
Entrances to all buildings, rooms or enclosures containing exposed live parts or exposed conductors operating at over 600 volts, nominal, must be kept locked unless a qualified person observes them at all times, and must have permanent and conspicuous warning signs reading substantially "DANGER—HIGH VOLTAGE—KEEP OUT."
“The following requirements apply to the entrances to all buildings, rooms, or enclosures containing exposed live parts or exposed conductors operating at over 600 volts, nominal: (A) The entrances shall be kept locked unless they are under the observation of a qualified person at all times; and (B) Permanent and conspicuous warning signs shall be provided, reading substantially as follows: “DANGER—HIGH VOLTAGE—KEEP OUT.””
Grounding and GFCI protection
Subpart S defines a ground-fault circuit-interrupter as a device for the protection of personnel that deenergizes a circuit, or part of one, within an established period of time when a current to ground exceeds a predetermined value that is less than what is needed to operate the overcurrent protective device of the supply circuit.
“A device intended for the protection of personnel that functions to deenergize a circuit or a portion of a circuit within an established period of time when a current to ground exceeds some predetermined value that is less than that required to operate the overcurrent protective device of the supply circuit.”
All 125-volt, single-phase, 15- and 20-ampere receptacles installed in bathrooms or on rooftops must have ground-fault circuit-interrupter protection for personnel.
“All 125-volt, single-phase, 15- and 20-ampere receptacles installed in bathrooms or on rooftops shall have ground-fault circuit-interrupter protection for personnel.”
That bathroom and rooftop GFCI requirement (1910.304(b)(3)(i)) is on the list in 1910.302 of requirements that apply only to electrical installations and utilization equipment installed after August 13, 2007.
“The following requirements apply only to electrical installations and utilization equipment installed after August 13, 2007: § 1910.303(f)(4)—Disconnecting means and circuits—Capable of accepting a lock § 1910.303(f)(5)—Disconnecting means and circuits—Marking for series combination ratings § 1910.303(g)(1)(iv) and (g)(1)(vii)—600 Volts, nominal, or less—Space about electric equipment § 1910.303(h)(5)(vi)—Over 600 volts, nominal—Working space and guarding § 1910.304(b)(1)—Branch circuits—Identification of multiwire branch circuits § 1910.304(b)(3)(i)—Branch circuits—Ground-fault circuit interrupter protection for personnel”
For temporary wiring installations used during "construction-like activities, including certain maintenance, remodeling, or repair activities, involving buildings, structures or equipment," all 125-volt, single-phase, 15-, 20- and 30-ampere receptacle outlets that are not part of the permanent wiring of the building or structure and that are in use by personnel must have GFCI protection for personnel.
“The following requirements apply to temporary wiring installations that are used during construction-like activities, including certain maintenance, remodeling, or repair activities, involving buildings, structures or equipment. (A) All 125-volt, single-phase,15-, 20-, and 30-ampere receptacle outlets that are not part of the permanent wiring of the building or structure and that are in use by personnel shall have ground-fault circuit-interrupter protection for personnel.”
Other temporary receptacles (not 125-volt, single-phase, 15-, 20- or 30-ampere) that are not part of the permanent wiring and are in use by personnel must also have GFCI protection. Where that GFCI protection is not available for them, the employer must establish and implement an assured equipment grounding conductor program.
“Receptacles other than 125 volt, single-phase, 15-, 20-, and 30-ampere receptacles that are not part of the permanent wiring of the building or structure and that are in use by personnel shall have ground-fault circuit-interrupter protection for personnel. (C) Where the ground-fault circuit-interrupter protection required by paragraph (b)(3)(ii)(B) of this section is not available for receptacles other than 125-volt, single-phase, 15-, 20-, and 30-ampere, the employer shall establish and implement an assured equipment grounding conductor program”
Under that program, each cord set, attachment cap, plug and receptacle of cord sets, and any equipment connected by cord and plug must be visually inspected before each day's use for external defects and for indications of possible internal damage, except cord sets and receptacles that are fixed and not exposed to damage. Equipment found damaged or defective may not be used until repaired.
“Each cord set, attachment cap, plug, and receptacle of cord sets, and any equipment connected by cord and plug, except cord sets and receptacles which are fixed and not exposed to damage, shall be visually inspected before each day's use for external defects, such as deformed or missing pins or insulation damage, and for indications of possible internal damage. Equipment found damaged or defective shall not be used until repaired;”
The program's required tests must be performed before first use, before equipment is returned to service after any repairs, before equipment is used after any incident that can reasonably be suspected to have caused damage (for example, a cord set being run over), and at intervals not to exceed 3 months. Cord sets and receptacles that are fixed and not exposed to damage are tested at intervals not exceeding 6 months.
“All required tests shall be performed before first use; before equipment is returned to service following any repairs; before equipment is used after any incident which can be reasonably suspected to have caused damage (for example, when a cord set is run over); and at intervals not to exceed 3 months, except that cord sets and receptacles which are fixed and not exposed to damage shall be tested at intervals not exceeding 6 months;”
The path to ground from circuits, equipment and enclosures must be permanent, continuous and effective.
“The path to ground from circuits, equipment, and enclosures shall be permanent, continuous, and effective.”
Not covered here
System grounding design (which systems must be grounded, grounding electrodes, high-voltage grounding) and overcurrent protection design in 1910.304. They are installation design details beyond this guide's focus. We only write what an official source states, so study these parts with your certifying program's materials.
Flexible cords and temporary wiring
Flexible cords and cables must be approved for the conditions of use and location.
“Flexible cords and cables shall be approved for conditions of use and location.”
29 CFR 1910.305, Wiring methods, components, and equipment for general use
Flexible cords and cables may be used only for the uses the rule lists: pendants; wiring of fixtures; connection of portable lamps or appliances; portable and mobile signs; elevator cables; wiring of cranes and hoists; connection of stationary equipment to facilitate their frequent interchange; prevention of the transmission of noise or vibration; appliances whose fastening means and mechanical connections are designed to permit removal for maintenance and repair; data processing cables approved as part of the data processing system; connection of moving parts; and temporary wiring as permitted in 1910.305(a)(2).
“Flexible cords and cables may be used only for: (A) Pendants; (B) Wiring of fixtures; (C) Connection of portable lamps or appliances; (D) Portable and mobile signs; (E) Elevator cables; (F) Wiring of cranes and hoists; (G) Connection of stationary equipment to facilitate their frequent interchange; (H) Prevention of the transmission of noise or vibration; (I) Appliances where the fastening means and mechanical connections are designed to permit removal for maintenance and repair; (J) Data processing cables approved as a part of the data processing system; (K) Connection of moving parts; and (L) Temporary wiring as permitted in paragraph (a)(2) of this section.”
29 CFR 1910.305, Wiring methods, components, and equipment for general use
Unless specifically permitted otherwise in the list of uses, flexible cords and cables may not be used as a substitute for the fixed wiring of a structure; where run through holes in walls, ceilings or floors; where run through doorways, windows or similar openings; where attached to building surfaces; where concealed behind building walls, ceilings or floors; or where installed in raceways, except as otherwise permitted in Subpart S.
“Unless specifically permitted otherwise in paragraph (g)(1)(ii) of this section, flexible cords and cables may not be used: (A) As a substitute for the fixed wiring of a structure; (B) Where run through holes in walls, ceilings, or floors; (C) Where run through doorways, windows, or similar openings; (D) Where attached to building surfaces; (E) Where concealed behind building walls, ceilings, or floors; or (F) Where installed in raceways, except as otherwise permitted in this subpart.”
29 CFR 1910.305, Wiring methods, components, and equipment for general use
Flexible cords may be used only in continuous lengths without splice or tap. Hard-service cord and junior hard-service cord No. 14 and larger may be repaired if spliced so that the splice keeps the insulation, outer sheath properties and usage characteristics of the cord. Flexible cords and cables must be connected to devices and fittings with strain relief, so that pull is not transmitted directly to joints or terminal screws.
“Flexible cords may be used only in continuous lengths without splice or tap. Hard-service cord and junior hard-service cord No. 14 and larger may be repaired if spliced so that the splice retains the insulation, outer sheath properties, and usage characteristics of the cord being spliced. (iii) Flexible cords and cables shall be connected to devices and fittings so that strain relief is provided that will prevent pull from being directly transmitted to joints or terminal screws.”
29 CFR 1910.305, Wiring methods, components, and equipment for general use
Temporary power and lighting installations of 600 volts, nominal, or less may be used only during and for remodeling, maintenance or repair of buildings, structures or equipment and similar activities; for a period not to exceed 90 days for Christmas decorative lighting, carnivals and similar purposes; or for experimental or development work and during emergencies.
“Temporary electrical power and lighting installations of 600 volts, nominal, or less may be used only as follows: (A) During and for remodeling, maintenance, or repair of buildings, structures, or equipment, and similar activities; (B) For a period not to exceed 90 days for Christmas decorative lighting, carnivals, and similar purposes; or (C) For experimental or development work, and during emergencies.”
29 CFR 1910.305, Wiring methods, components, and equipment for general use
Temporary wiring must be removed immediately when the project or purpose it was installed for is complete.
“Temporary wiring shall be removed immediately upon completion of the project or purpose for which the wiring was installed.”
29 CFR 1910.305, Wiring methods, components, and equipment for general use
Qualified persons and training
Sections 1910.331 through 1910.335 cover electrical safety-related work practices for both qualified persons (those who have training in avoiding the electrical hazards of working on or near exposed energized parts) and unqualified persons (those with little or no such training) working on, near or with the installations listed in 1910.331(a), such as premises wiring.
“The provisions of §§ 1910.331 through 1910.335 cover electrical safety-related work practices for both qualified persons (those who have training in avoiding the electrical hazards of working on or near exposed energized parts) and unqualified persons (those with little or no such training) working on, near, or with the following installations: (1) Premises wiring.”
Subpart S defines a qualified person as one who has received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved. A note says that whether an employee is considered a qualified person depends on various circumstances in the workplace.
“One who has received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved. Note 1 to the definition of “qualified person:” Whether an employee is considered to be a “qualified person” will depend upon various circumstances in the workplace.”
A note to the definition says an employee undergoing on-the-job training who, in the course of that training, has demonstrated an ability to perform duties safely at his or her level of training and who is under the direct supervision of a qualified person is considered a qualified person for the performance of those duties.
“An employee who is undergoing on-the-job training and who, in the course of such training, has demonstrated an ability to perform duties safely at his or her level of training and who is under the direct supervision of a qualified person is considered to be a qualified person for the performance of those duties.”
The training rules apply to employees who face a risk of electric shock that is not reduced to a safe level by the electrical installation requirements of 1910.303 through 1910.308. A note says employees in the occupations listed in Table S-4 face such a risk and are required to be trained, and other employees who may reasonably be expected to face a comparable risk of injury due to electric shock or other electrical hazards must also be trained.
“apply to employees who face a risk of electric shock that is not reduced to a safe level by the electrical installation requirements of §§ 1910.303 through 1910.308. Note: Employees in occupations listed in Table S-4 face such a risk and are required to be trained. Other employees who also may reasonably be expected to face a comparable risk of injury due to electric shock or other electrical hazards must also be trained.”
Qualified persons (those permitted to work on or near exposed energized parts) must, at a minimum, be trained in and familiar with the skills and techniques to distinguish exposed live parts from other parts of electric equipment, the skills and techniques to determine the nominal voltage of exposed live parts, and the clearance distances in 1910.333(c) and the corresponding voltages to which they will be exposed.
“Qualified persons (i.e., those permitted to work on or near exposed energized parts) shall, at a minimum, be trained in and familiar with the following: (i) The skills and techniques necessary to distinguish exposed live parts from other parts of electric equipment, (ii) The skills and techniques necessary to determine the nominal voltage of exposed live parts, and (iii) The clearance distances specified in § 1910.333(c) and the corresponding voltages to which the qualified person will be exposed.”
The training must be of the classroom or on-the-job type, and the degree of training is determined by the risk to the employee.
“The training required by this section shall be of the classroom or on-the-job type. The degree of training provided shall be determined by the risk to the employee.”
Not covered here
The work excluded from 1910.331 through 1910.335 when done by qualified persons (for example generation, transmission and distribution installations covered by 1910.269, and communications work covered by 1910.268). Those sections have their own rules. We only write what an official source states, so study these parts with your certifying program's materials.
Deenergizing and lockout
Live parts an employee may be exposed to must be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations.
“Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations.”
Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.
“Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.”
Conductors and parts that have been deenergized but not locked out or tagged under 1910.333(b) must be treated as energized parts.
“Conductors and parts of electric equipment that have been deenergized but have not been locked out or tagged in accordance with paragraph (b) of this section shall be treated as energized parts”
While any employee is exposed to contact with parts of fixed electric equipment or circuits that have been deenergized, the circuits energizing the parts must be locked out or tagged or both under 1910.333(b)(2), and its requirements must be followed in the order presented.
“While any employee is exposed to contact with parts of fixed electric equipment or circuits which have been deenergized, the circuits energizing the parts shall be locked out or tagged or both in accordance with the requirements of this paragraph. The requirements shall be followed in the order in which they are presented”
A note says lockout and tagging procedures that comply with paragraphs (c) through (f) of 1910.147 are also deemed to comply with 1910.333(b)(2), provided the procedures address the electrical safety hazards covered by Subpart S and also incorporate the requirements of 1910.333(b)(2)(iii)(D) and (b)(2)(iv)(B).
“Lockout and tagging procedures that comply with paragraphs (c) through (f) of § 1910.147 will also be deemed to comply with paragraph (b)(2) of this section provided that: (1) The procedures address the electrical safety hazards covered by this Subpart; and (2) The procedures also incorporate the requirements of paragraphs (b)(2)(iii)(D) and (b)(2)(iv)(B) of this section.”
Control circuit devices such as push buttons, selector switches and interlocks may not be used as the sole means for deenergizing circuits or equipment, and interlocks for electric equipment may not be used as a substitute for lockout and tagging procedures.
“Control circuit devices, such as push buttons, selector switches, and interlocks, may not be used as the sole means for deenergizing circuits or equipment. Interlocks for electric equipment may not be used as a substitute for lockout and tagging procedures.”
A lock and a tag must be placed on each disconnecting means used to deenergize circuits and equipment on which work is to be performed, except where 1910.333(b)(2)(iii)(C) and (E) allow a tag without a lock or a lock without a tag. The lock must be attached so that persons cannot operate the disconnecting means unless they resort to undue force or the use of tools.
“A lock and a tag shall be placed on each disconnecting means used to deenergize circuits and equipment on which work is to be performed, except as provided in paragraphs (b)(2)(iii)(C) and (b)(2)(iii)(E) of this section. The lock shall be attached so as to prevent persons from operating the disconnecting means unless they resort to undue force or the use of tools.”
A lock may be placed without a tag only when just one circuit or piece of equipment is deenergized, the lockout period does not extend beyond the work shift, and employees exposed to reenergizing hazards are familiar with this procedure.
“A lock may be placed without a tag only under the following conditions: (1) Only one circuit or piece of equipment is deenergized, and (2) The lockout period does not extend beyond the work shift, and (3) Employees exposed to the hazards associated with reenergizing the circuit or equipment are familiar with this procedure.”
Before circuits or equipment can be considered and worked as deenergized, a qualified person must operate the equipment operating controls or otherwise verify that the equipment cannot be restarted, and a qualified person must use test equipment to test the circuit elements and electrical parts employees will be exposed to and verify that they are deenergized. The test must also determine whether any energized condition exists from inadvertently induced voltage or unrelated voltage backfeed. If the circuit is over 600 volts, nominal, the test equipment must be checked for proper operation immediately before and immediately after the test.
“Verification of deenergized condition. The requirements of this paragraph shall be met before any circuits or equipment can be considered and worked as deenergized. (A) A qualified person shall operate the equipment operating controls or otherwise verify that the equipment cannot be restarted. (B) A qualified person shall use test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall verify that the circuit elements and equipment parts are deenergized. The test shall also determine if any energized condition exists as a result of inadvertently induced voltage or unrelated voltage backfeed even though specific parts of the circuit have been deenergized and presumed to be safe. If the circuit to be tested is over 600 volts, nominal, the test equipment shall be checked for proper operation immediately before and immediately after this test.”
Not covered here
The full text of 1910.147 (the control of hazardous energy), which has its own study guide. We only write what an official source states, so study these parts with your certifying program's materials.
Work near energized parts and overhead lines
Only qualified persons may work on electric circuit parts or equipment that have not been deenergized under the procedures of 1910.333(b).
“Only qualified persons may work on electric circuit parts or equipment that have not been deenergized under the procedures of paragraph (b) of this section.”
If work is to be performed near overhead lines, the lines must be deenergized and grounded, or other protective measures must be provided, before work is started.
“If work is to be performed near overhead lines, the lines shall be deenergized and grounded, or other protective measures shall be provided before work is started.”
When an unqualified person is working in an elevated position near overhead lines, the location must be such that the person and the longest conductive object he or she may contact cannot come closer to any unguarded, energized overhead line than 10 ft. (305 cm) for voltages to ground 50kV or below, or 10 ft. (305 cm) plus 4 in. (10 cm) for every 10kV over 50kV for voltages to ground over 50kV.
“When an unqualified person is working in an elevated position near overhead lines, the location shall be such that the person and the longest conductive object he or she may contact cannot come closer to any unguarded, energized overhead line than the following distances: (1) For voltages to ground 50kV or below—10 ft. (305 cm); (2) For voltages to ground over 50kV—10 ft. (305 cm) plus 4 in. (10 cm) for every 10kV over 50kV.”
An unqualified person working on the ground in the vicinity of overhead lines may not bring any conductive object closer to unguarded, energized overhead lines than those same distances.
“When an unqualified person is working on the ground in the vicinity of overhead lines, the person may not bring any conductive object closer to unguarded, energized overhead lines than the distances given in paragraph (c)(3)(i)(A) of this section.”
Any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines must be operated so that a clearance of 10 ft. (305 cm) is maintained; if the voltage is higher than 50kV, the clearance is increased 4 in. (10 cm) for every 10kV over that voltage. The clearance may be reduced only under listed conditions; for example, a vehicle in transit with its structure lowered may have its clearance reduced to 4 ft. (122 cm), increased 4 in. (10 cm) for every 10kV over 50kV.
“Any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines shall be operated so that a clearance of 10 ft. (305 cm) is maintained. If the voltage is higher than 50kV, the clearance shall be increased 4 in. (10 cm) for every 10kV over that voltage. However, under any of the following conditions, the clearance may be reduced: (1) If the vehicle is in transit with its structure lowered, the clearance may be reduced to 4 ft. (122 cm). If the voltage is higher than 50kV, the clearance shall be increased 4 in. (10 cm) for every 10kV over that voltage.”
Portable ladders must have nonconductive siderails if they are used where the employee or the ladder could contact exposed energized parts.
“Portable ladders shall have nonconductive siderails if they are used where the employee or the ladder could contact exposed energized parts.”
Not covered here
The Table S-5 approach distances for qualified employees, which apply to trained qualified persons rather than to the general workforce this guide is written for. We only write what an official source states, so study these parts with your certifying program's materials.
Portable equipment and PPE
Portable equipment must be handled in a manner that will not cause damage. Flexible electric cords connected to equipment may not be used for raising or lowering the equipment, and flexible cords may not be fastened with staples or otherwise hung in a way that could damage the outer jacket or insulation.
“Portable equipment shall be handled in a manner which will not cause damage. Flexible electric cords connected to equipment may not be used for raising or lowering the equipment. Flexible cords may not be fastened with staples or otherwise hung in such a fashion as could damage the outer jacket or insulation.”
Portable cord- and plug-connected equipment and flexible cord sets (extension cords) must be visually inspected before use on any shift for external defects and for evidence of possible internal damage. Items that remain connected once they are put in place and are not exposed to damage need not be visually inspected until they are relocated.
“Portable cord- and plug-connected equipment and flexible cord sets (extension cords) shall be visually inspected before use on any shift for external defects (such as loose parts, deformed and missing pins, or damage to outer jacket or insulation) and for evidence of possible internal damage (such as pinched or crushed outer jacket). Cord- and plug-connected equipment and flexible cord sets (extension cords) which remain connected once they are put in place and are not exposed to damage need not be visually inspected until they are relocated.”
Adapters that interrupt the continuity of the equipment grounding connection may not be used.
“Adapters which interrupt the continuity of the equipment grounding connection may not be used.”
Employees' hands may not be wet when plugging and unplugging flexible cords and cord- and plug-connected equipment, if energized equipment is involved.
“Employees' hands may not be wet when plugging and unplugging flexible cords and cord- and plug-connected equipment, if energized equipment is involved.”
Employees working in areas with potential electrical hazards must be provided with, and must use, electrical protective equipment appropriate for the parts of the body to be protected and for the work to be performed. That equipment must be kept in a safe, reliable condition and periodically inspected or tested as required by 1910.137.
“Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body to be protected and for the work to be performed. Note: Personal protective equipment requirements are contained in subpart I of this part. (ii) Protective equipment shall be maintained in a safe, reliable condition and shall be periodically inspected or tested, as required by § 1910.137.”
Employees must wear nonconductive head protection wherever there is a danger of head injury from electric shock or burns due to contact with exposed energized parts, and protective equipment for the eyes or face wherever there is danger of injury to the eyes or face from electric arcs or flashes or from flying objects resulting from electrical explosion.
“Employees shall wear nonconductive head protection wherever there is a danger of head injury from electric shock or burns due to contact with exposed energized parts. (v) Employees shall wear protective equipment for the eyes or face wherever there is danger of injury to the eyes or face from electric arcs or flashes or from flying objects resulting from electrical explosion.”
Conductive jewelry and clothing (such as watch bands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread or metal headgear) may not be worn if they might contact exposed energized parts, unless they are rendered nonconductive by covering, wrapping or other insulating means.
“Conductive articles of jewelry and clothing (such as watch bands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread, or metal headgear) may not be worn if they might contact exposed energized parts. However, such articles may be worn if they are rendered nonconductive by covering, wrapping, or other insulating means.”
Sources
- eCFR: 29 CFR 1910.303, General (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.302, Electric utilization systems (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.399, Definitions applicable to this subpart (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.304, Wiring design and protection (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.305, Wiring methods, components, and equipment for general use (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.331, Scope (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.332, Training (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.333, Selection and use of work practices (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.334, Use of equipment (as of Nov 3, 2026)Checked November 5, 2026
- eCFR: 29 CFR 1910.335, Safeguards for personnel protection (as of Nov 3, 2026)Checked November 5, 2026
Other OSHA General Industry study guides: Walking-working surfaces, Exit routes and emergency planning, Fire protection, Personal protective equipment, Hazardous materials, Permit-required confined spaces, Lockout/tagout, Machine guarding, Welding, cutting and brazing, Electric power generation, transmission and distribution, Powered industrial trucks (forklifts), Materials handling and storage, Bloodborne pathogens, Occupational noise exposure