<< Back to Construction Outreach Program

Construction Safety and Health
Outreach Program
U.S. Department of Labor
OSHA Office of Training and Education
May 1996



Power SystemThe occupational safety and health standard contained in this Subpart V applies to the construction of electric transmission and distribution lines and equipment. The term "construction" as used here includes the erection of new electric transmission and distribution lines and equipment, and the alteration, conversion, and improvement of existing electric transmission and distribution lines and equipment.

Existing electric transmission and distribution lines and electrical equipment need not be modified to conform to the requirements of applicable standards in this subpart, until "construction" work as described above is to be performed on such lines or equipment.

The standards set forth in this Subpart V provide minimum requirements for safety and health. Employers may require adherence to additional standards which are not in conflict with these standards. OSHA has promulgated a general industry standard to protect employees from the hazards arising out of the operation or maintenance of electric power generation, transmission and distribution installations (29 CFR 1910.269). Although this standard does not apply to construction work, the reader is encouraged to refer to it for general information, since it is provides comprehensive safe work practices.

Initial Inspections, Tests, or Determinations

Existing conditions shall be determined before starting work, by an inspection or a test. Such conditions shall include, but not be limited to, energized lines and equipment, conditions of poles, and the location of circuits and equipment, including power and communication lines, CATV and fire alarm circuits.

Electric equipment and lines shall be considered energized until determined to be deenergized by tests or other appropriate methods or means.

Operating voltage of equipment and lines shall be determined before working on or near energized parts.


No employee shall be permitted to approach or take any conductive object without an approved insulating handle closer to exposed energized parts than shown in Table V-1, unless:

  • The employee is insulated or guarded from the energized part (gloves or gloves with sleeves rated for the voltage involved shall be considered insulation of the employee from the energized part), or
  • The energized part is insulated or guarded from him/her and any other conductive object at a different potential, or
  • The employee is isolated, insulated, or guarded from any other conductive object(s), as during live-line bare-hand work.

The minimum working distance and minimum clear hot stick distances stated in Table V-1 shall not be violated. The minimum clear hot stick distance is that for the use of live-line tools held by linemen when performing live-line work.

Conductor support tools, such as link sticks, strain carriers, and insulator cradles, may be used: Provided, that the clear insulation is at least as long as the insulator string or the minimum distance specified in Table V-1 for the operating voltage.


Alternating Current - Minimum Distances
Voltage Range (phase to phase)

Minimum Working and

Clear Hot Stick Distance
2.1 to 15 2 ft. 0 in.
15.1 to 35 2 ft. 4 in.
35.1 to 46 2 ft. 6 in.
46.1 to 72.5 3 ft. 0 in.
72.6 to 121 3 ft. 4 in.
138 to 145 3 ft. 6 in.
161 to 169 3 ft. 8 in.
230 to 242 5 ft. 0 in.
345 to 362 7 ft. 0 in.*
500 to 552 11 ft. 0 in.*
700 to 765 15 ft. 0 in.*

* NOTE: From 345-362 kv., 500-552 kv., and 700-765 kv., the minimum working distance and the minimum clear hot stick distance may be reduced provided that such distances are not less than the shortest distance between the energized part and a grounded surface.

Deenergizing Lines and Equipment

When deenergizing lines and equipment operated in excess of 600 volts, and the means of disconnecting from electric energy is not visibly open or visibly locked out, the following provisions shall be complied with:

  • The particular section of line or equipment to be deenergized shall be clearly identified, and it shall be isolated from all sources of voltage.
  • Notification and assurance from the designated employee shall be obtained that:
      - All switches and disconnectors through which electric energy may be supplied to the particular section of line or equipment to be worked have been deenergized;
      - All switches and disconnectors are plainly tagged indicating that employees are at work;
      - And that where design of such switches and disconnectors permits, they have been rendered inoperable.
  • After all designated switches and disconnectors have been opened, rendered inoperable, and tagged, visual inspection or tests shall be conducted to insure that equipment or lines have been deenergized.
  • Protective grounds shall be applied on the disconnected lines or equipment to be worked on.
  • Guards or barriers shall be erected as necessary to adjacent energized lines.
  • When more than one independent crew requires the same line or equipment to be deenergized, a prominent tag for each such independent crew shall be placed on the line or equipment by the designated employee in charge.
  • Upon completion of work on deenergized lines or equipment, each designated employee in charge shall determine that all employees in his/her crew are clear, that protective grounds installed by his/her crew have been removed, and he/she shall report to the designated authority that all tags protecting his/her crew may be removed.

When a crew working on a line or equipment can clearly see that the means of disconnecting from electric energy are visibly open or visibly locked-out, the following provisions shall apply:

  • Guards or barriers shall be erected as necessary to adjacent energized lines.
  • Upon completion of work on deenergized lines or equipment, each designated employee in charge shall determine that all employees in their crew are clear, that protective grounds installed by their crew have been removed, and he/she shall report to the designated authority that all tags protecting their crew may be removed.

Emergency Procedures and First Aid

The employer shall provide training or require that his/her employees are knowledgeable and proficient in:

  • Procedures involving emergency situations, and
  • First-aid fundamentals including resuscitation.

In lieu of the above requirements, the employer may comply with the provisions of §1926.50(c) regarding first-aid requirements.

Night Work

When working at night, spotlights or portable lights for emergency lighting shall be provided as needed to the perform the work safely.

Work Near and Over Water

When crews are engaged in work over or near water and when danger of drowning exists, suitable protection shall be provided as stated in §1926.104, or §1926.105, or §1926.106.

Sanitation Facilities

The requirements of §1926.51 of Subpart D of Part 1926, Occupational Health and Environmental Controls, shall be complied with for sanitation facilities.

Hydraulic Fluids

All hydraulic fluids used for the insulated sections of derrick trucks, aerial lifts, and hydraulic tools which are used on or around energized lines and equipment shall be of the insulating type. The requirements for fire resistant fluids of §1926.302(d)(1) do not apply to hydraulic tools covered by this paragraph.


Protective Equipment

Rubber protective equipment shall be in accordance with the provisions of the American National Standards Institute (ANSI), ANSI J6 series, as follows:

Rubber insulating gloves J6.6-1971
Rubber matting for use around electric apparatus J6.7-1935 (R1971)
Rubber insulating blankets J6.4-1971
Rubber insulating hoods J6.2-1950 (R1971)
Rubber insulating line hose J6.1-1950 (R1971)
Rubber insulating sleeves J6.5-1971

Rubber protective equipment shall be visually inspected prior to use. In addition, an "air" test shall be performed for rubber gloves prior to use.

Protective equipment of material other than rubber shall provide equal or better electrical and mechanical protection.

Protective hats shall be in accordance with the provisions of ANSI Z89.2 - 1971, Industrial Protective Helmets for Electrical Workers, Class B, and shall be worn at the jobsite by employees who are exposed to the hazards of falling objects, electric shock, or burns.

Personal Climbing Equipment

Body belts with straps or lanyards shall be worn to protect employees working at elevated locations on poles, towers, or other structures except where such use creates a greater hazard to the safety of the employees, in which case other safeguards shall be employed.

Body belts and safety straps shall meet the requirements of §1926.959. In addition to being used as an employee safeguarding item, body belts with approved tool loops may be used for the purpose of holding tools. Body belts shall be free from additional metal hooks and tool loops other than those permitted in §1926.959.

Body belts and straps shall be inspected before use and each day to determine that they are in safe working condition.

Life lines and lanyards shall comply with the provisions of §1926.104.

Safety lines are not intended to be subjected to shock loading and are used for emergency rescue such as lowering a person to the ground. Such safety lines shall be a minimum of =-inch diameter and three or four strand first-grade manila or its equivalent in strength (2,650 lb.) and durability.

Defective ropes shall be replaced.


Portable metal or conductive ladders shall not be used near energized lines or equipment except as may be necessary in specialized work such as in high voltage substations where nonconductive ladders might present a greater hazard than conductive ladders. Conductive or metal ladders shall be prominently marked as conductive and all necessary precautions shall be taken when used in specialized work.

Hook or other type ladders used in structures shall be positively secured to prevent the ladder from being accidently displaced.

Live-Line Tools

Only live-line tool poles having a manufacturer's certification to withstand the following minimum tests shall be used:

  • 100,000 volts per foot of length for 5 minutes when the tool is made of fiberglass; or
  • 75,000 volts per foot of length for 3 minutes when the tool is made of wood; or
  • Other tests equivalent to these tests as appropriate.

All live-line tools shall be visually inspected before use each day. Tools to be used shall be wiped clean and if any hazardous defects are indicated, removed from service.

Measuring Tapes or Measuring Ropes

Measuring tapes or measuring ropes which are metal or contain conductive strands shall not be used when working on or near energized parts.

Hand Tools

Switches for all powered hand tools shall comply with §1926.300(d).

All portable electric hand tools shall:

  • Be equipped with three-wire cord having the ground wire permanently connected to the tool frame and means for grounding the other end; or
  • Be of the double insulated type and permanently labeled as "Double Insulated"; or
  • Be connected to the power supply by means of an isolating transformer, or other isolated power supply.

All hydraulic tools which are used on or around energized lines or equipment shall use nonconducting hoses having adequate strength for the normal operating pressures. It should be noted that the provisions of §1926.302(d)(2) shall also apply.

All pneumatic tools which are used on or around energized lines or equipment shall:

  • Have nonconducting hoses having adequate strength for the normal operating pressures, and
  • Have an accumulator on the compressor to collect moisture.



Visual inspections of the equipment shall be made to determine that it is in good condition each day the equipment is to be used.

Tests shall be made at the beginning of each shift during which the equipment is to be used to determine that the brakes and operating systems are in proper working condition.

No employer shall use any motor vehicle equipment having an obstructed view to the rear unless:

  • The vehicle had a reverse signal alarm audible above the surrounding noise level, or
  • The vehicle is backed up only when an observer signals that it is safe to do so.

Aerial Lifts

The provisions of §1926.556 shall apply to the utilization of aerial lifts.

When working near energized lines or equipment, aerial lift trucks shall be grounded or barricaded and considered as energized equipment, or the aerial lift truck shall be insulated for the work being performed.

Equipment or material shall not be passed between a pole or structure and an aerial lift while an employee working from the basket is within reaching distance of energized conductors or equipment that are not covered with insulating protective equipment.

Derrick Trucks, Cranes and Other Lifting Equipment

All derrick trucks, cranes and other lifting equipment shall comply with Subparts N and O of Part 1926 except:

  • As stated in §1926.550(a)(15)(i) and (ii) relating to clearance (for clearances in this subpart see Table V-1), and
  • Derrick truck (electric line trucks) shall not be required to comply with §1926.550(a)(7)(vi), (a)(17), (b)(2), and (e).

With the exception of equipment certified for work on the proper voltage, mechanical equipment shall not be operated closer to any energized line or equipment than the clearances set forth in §1926.950(c) unless:

  • An insulated barrier is installed between the energized part and the mechanical equipment, or
  • The mechanical equipment is grounded, or
  • The mechanical equipment is insulated, or
  • The mechanical equipment is considered as energized.



Prior to unloading steel, poles, cross arms and similar material, the load shall be thoroughly examined to ascertain if the load has shifted, binders or stakes have broken or the load is otherwise hazardous to employees.

Pole Hauling

During pole hauling operations, all loads shall be secured to prevent displacement and a red flag shall be displayed at the trailing end of the longest pole.

Precautions shall be exercised to prevent blocking of roadways or endangering other traffic.

When hauling poles during the hours of darkness, illuminated warning devices shall be attached to the trailing end of the longest pole.


No materials or equipment shall be stored under energized bus, energized lines, or near energized equipment, if it is practical to store them elsewhere.

When materials or equipment are stored under energized lines or near energized equipment, applicable clearances shall be maintained as stated in Table V-1; and extraordinary caution shall be exercised when moving materials near such energized equipment.

Tag Line

Where hazards to employees exist, tag lines or other suitable devices shall be used to control loads being handled by hoisting equipment.

Oil Filled Equipment

During construction or repair of oil filled equipment, the oil may be stored in temporary containers other than those required in §1926.152, such as pillow tanks.


During framing operations, employees shall not work under a pole or a structure suspended by a crane, A-frame or similar equipment unless the pole or structure is adequately supported.

Attaching the Load

The hoist rope shall not be wrapped around the load. This provision shall not apply to electric construction crews when setting or removing poles.



All conductors and equipment shall be treated as energized until tested or otherwise determined to be deenergized or until grounded.

New Construction

New lines or equipment may be considered deenergized and worked as such where:

  • The lines or equipment are grounded, or
  • The hazard of induced voltages is not present, and adequate clearances or other means are implemented to prevent contact with energized lines or equipment and the new lines or equipment.

Communication Conductors

Bare wire communication conductors on power poles or structures shall be treated as energized lines unless protected by insulating materials.

Voltage Testing

Deenergized conductors and equipment which are to be grounded shall be tested for voltage. The results of this test shall determine the subsequent procedures as required in §1926.950(d).

Attaching Grounds

When attaching grounds, the ground end shall be attached first, and the other end shall be attached and removed by means of insulated tools or other suitable devices.

When removing grounds, the grounding device shall first be removed from the line or equipment using insulating tools or other suitable devices.

Grounds Placement

Grounds shall be placed between the work location and all sources of energy and as close as practicable to the work location, or grounds shall be placed at the work location. If work is to be performed at more than one location in a line section, the line section must be grounded and short circuited at one location in the line section and the conductor to worked on shall be grounded at each work location. The minimum distance shown in Table V-1 shall be maintained from ungrounded conductors at the work location. Where the making of a ground is impracticable, or the conditions resulting would be more hazardous than working on the lines or equipment without grounding, the grounds may be omitted and the line or equipment worked as energized.

Testing Without Grounds

Grounds may be temporarily removed only when necessary for test purposes and extreme caution shall be exercised during the test procedures.

Grounding Electrode

When grounding electrodes are utilized, such electrodes shall have a resistance to ground low enough to remove the danger of harm to personnel or permit prompt operation of protective devices.

Grounding to Tower

Grounding to tower shall be made with a tower clamp capable of conducting the anticipated fault current.

Ground Lead

A ground lead, to be attached to either a tower ground or driven ground, shall be capable of conducting the anticipated fault current and have a minimum conductance of No. 2 AWG copper.

OVERHEAD LINES - §1926.955

When working on or with overhead lines, the following provisions shall be complied with:

  • Prior to climbing poles, ladders, scaffolds, or other elevated structures, an inspection shall be made to determine that the structures are capable of sustaining the additional or unbalanced stresses to which they will be subjected.
  • Where poles or structures may be unsafe for climbing, they shall not be climbed until made safe by guying, bracing, or other adequate means.
  • Before installing or removing wire or cable, strains to which poles and structures will be subjected shall be considered and necessary action taken to prevent failure of supporting structures.
  • When setting, moving, or removing poles using cranes, derricks, gin poles, A-frames, or other mechanized equipment near energized lines or equipment, precautions shall be taken to avoid contact with energized lines or equipment, except in bare-hand live-line work, or where barriers or protective devices are used.
  • Equipment and machinery operating adjacent to energized lines or equipment shall comply with §1926.952(c)(2).
  • Unless using suitable protective equipment for the voltage involved, employees standing on the ground shall avoid contacting equipment or machinery working adjacent to energized lines or equipment.
  • Lifting equipment shall be bonded to an effective ground or it shall be considered energized and barricaded when utilized near energized equipment or lines.
  • Pole holes shall not be left unattended or unguarded in areas where employees are currently working.
  • Tag lines shall be of a nonconductive type when used near energized lines.

This section (§1926.955) also contains requirements for metal tower construction, stringing or removing deenergized conductors, stringing adjacent to energized lines, and live-line bare-hand work.


Guarding and Ventilating Street Opening Used for Access to Underground Lines or Equipment

Appropriate warning signs shall be promptly placed when covers of manholes, handholes, or vaults are removed. The nature and location of the hazards involved determine what is an appropriate warning sign.

Before an employee enters a street opening, such as a manhole or an unvented vault, it shall be promptly protected with a barrier, temporary cover, or other suitable guard.

When work is to be performed in a manhole or unvented vault:

  • No entry shall be permitted unless forced ventilation is provided or the atmosphere is found to be safe by testing for oxygen deficiency and the presence of explosive gases or fumes;
  • Where unsafe conditions are detected, by testing or other means, the work area shall be ventilated and otherwise made safe before entry;
  • Provisions shall be made for an adequate continuous supply of air.

Work in Manholes

While work is being performed in manholes, an employee shall be available in the immediate vicinity to render emergency assistance as may be required. This shall not preclude the employee in the immediate vicinity from occasionally entering a manhole to provide assistance, other than an emergency. This requirement does not preclude a qualified employee, working alone, from entering for brief periods of time, a manhole where energized cables or equipment are in service, for the purpose of inspection, housekeeping, taking readings, or similar work if such work can be performed safely.

When open flames must be used or smoking is permitted in manholes, extra precautions shall be taken to provide adequate ventilation.

Before using open flames in a manhole or excavation in an area where combustible gases or liquids may be present, such as near a gasoline service station, the atmosphere of the manhole or excavation shall be tested and found safe or cleared of the combustible gases or liquids.

Trenching and Excavating

  • During excavation or trenching, in order to prevent the exposure of employees to the hazards created by damage to dangerous underground facilities, efforts shall be made to determine the location of such facilities and work conducted in a manner designed to avoid damage.
  • Trenching and excavation operations shall comply with §1926.651 and 1926.652.
  • When underground facilities are exposed (electric, gas, water, telephone, etc.) they shall be protected as necessary to avoid damage.
  • Where multiple cables exist in an excavation, cables other than the one being worked on shall be protected as necessary.
  • When multiple cables exist in an excavation, the cable to be worked on shall be identified by electrical means unless its identity is obvious by reason of distinctive appearance.
  • Before cutting into a cable or opening a splice, the cable shall be identified and verified to be the proper cable.
  • When working on buried cable or on cable in manholes, metallic sheath continuity shall be maintained by bonding across the opening or by equivalent means.


Work Near Energized Equipment Facilities

When construction work is performed in an energized substation, authorization shall be obtained from the designated, authorized person before work is started, and the following shall be determined:

  • What facilities are energized, and
  • What protective equipment and precautions are necessary for the safety of personnel.

Extraordinary caution shall be exercised in the handling of busbars, tower steel, materials, and equipment in the vicinity of energized facilities. The requirements set forth in §1926.950(c) shall be complied with.

Deenergized Equipment or Lines

When it is necessary to deenergize equipment or lines for protection of employees, the requirements of §1926.950(d) shall be complied with.

Barricades and Barriers

Barricades or barriers shall be installed to prevent accidental contact with energized lines or equipment.

Where appropriate, signs indicating the hazard shall be posted near the barricade or barrier. These signs shall comply with §1926.200.

Control Panels

Work on or adjacent to energized control panels shall be performed by designated employees.

Precaution shall be taken to prevent accidental operation of relays or other protective devices due to jarring, vibration, or improper wiring.

Mechanical Equipment

Use of vehicles, gin poles, cranes, and other equipment in restricted or hazardous areas shall at all times be controlled by designated employees.

All mobile cranes and derricks shall be effectively grounded when being moved or operated in close proximity to energized lines or equipment, or the equipment shall be considered energized.

Fenders shall not be required for lowboys used for transporting large electrical equipment, transformers, or breakers.


The storage requirements of §1926.953(c) shall be complied with.

Substation Fences

When a substation fence must be expanded or removed for construction purposes, a temporary fence affording similar protection when the site is unattended, shall be provided. Adequate interconnection with ground shall be maintained between temporary fence and permanent fence.

All gates to all unattended substations shall be locked, except when work is in progress.

Footing Excavation

Excavation for auger, pad and piling type footings for structures and towers shall require the same precautions as for metal tower construction [see §1926.955(b)(1)].

No employee shall be permitted to enter an unsupported auger-type excavation in unstable material for any purpose. Necessary clean-out in such cases shall be accomplished without entry.