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501 EM 385-1-1 Construction Safety Hazard Awareness for Contractors Sections 7 - 13
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501 EM 385-1-1 Construction Safety Hazard Awareness for Contractors Sections 7 - 13

11.I Power Transmission and Distribution.

11.I.01 The requirements in this subsection must apply to 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.

Workers on HV Line.
HV Transmission Line Construction

11.I.02 Before starting work, existing conditions must be evaluated and determined. Such conditions must include, but not be limited to, location and voltage of energized lines and equipment, conditions of poles, and location of circuits and equipment including power and communication lines and fire alarm circuits.

  1. Electric equipment and lines must be considered energized until determined to be de-energized by tests, or other means, and grounds applied.
  2. New lines or equipment may be considered de-energized and worked as such where the lines or equipment are grounded or where the hazard of induced voltages is not present and adequate clearances or other means are implemented to prevent contact with energized lines or equipment.
  3. The operating voltage of equipment and lines must be determined before working on or near energized parts.

11.I.03 Clearance requirements of either subparagraph a or b below must be observed.

  1. No QP must be permitted to approach or take any conductive object without an approved insulating handle closer to exposed energized parts than shown in Table 11-3 (phase to ground) unless:
    • (1) The QP is insulated or guarded from the energized part (gloves or gloves with sleeves rated for the voltage involved must be considered insulation of the QP from the energized part);
    • (2) The energized part is insulated or guarded from the QP and any other conductive object at a different potential; or
    • (3) The QP is isolated, insulated, or guarded from any other conductive object(s), as during live-line, bare-hand work.
Voltage in kV
(phase-to-
phase) 1,2		 Distance to Employee
Phase-to-ground Phase-to-phase
(m) (ft-in) (m) (ft-in)
0 to 0.050 Not specified Not specified
0.051 to 0.300 Avoid contact Avoid contact
0.301 to 0.750 0.31 1-0 0.31 1-0
0.751 to 15 0.65 2-2 0.67 2-3
15.1 to 36.0 0.77 2-7 0.86 2-10
36.1 to 46 0.84 2-9 0.96 3-2
46.1 to 72.5 1.003 3-33 1.20 3-11
72.6 to 121 0.953 3-23 1.29 4-3
138 to 145 1.09 3-7 1.50 4-11
161 to 169 1.22 4-0 1.71 5-8
230 to 242 1.59 5-3 2.27 7-6
345 to 362 2.59 8-6 3.80 12-6
500 to 550 3.42 11-3 5.50 18-1
765 to 800 4.53 14-11 7.91 26-0

1For single-phase systems use the highest voltage available.
2 For single-phase lines off three phase systems, use phase-to-phase voltage of the system.
3 The 46.1 to 72.5 kV phase-to-ground 3-3 (ft-in) distance contains a 1-3 (ft-in) electrical component and a 2-0 (ft-in) inadvertent movement component while the 72.6 to 121 kV phase-to-ground 3-2 (ft-in) distance contains a 2-0 (ft-in) electrical component and a 1-0 (ft-in) inadvertent movement component.

  1. The minimum phase to ground working distance and minimum clear hot stick distances in Table 11-3 must not be exceeded. The minimum clear hot stick distance refers to the distance from the hot end of live-line tools to the lineman when performing live-line work. Conductor support tools (such as link sticks, strain carriers, and insulator cradles) may be used provided the clear length of insulation is at least as long as the insulator string or as long as the minimum phase to ground distance in Table 11-3.

11.I.04 When de-energizing lines and equipment operated in excess of 600 volts, and the means of disconnecting from electric energy is not visibly open or visibly locked and tagged out, provisions a through g below are required. > In addition, requirements in Section 12 apply.

  1. The equipment or section of line to be de-energized must be clearly identified and must be isolated from all sources of voltage.
  2. Notification and assurance from the GDA must be obtained that:
    • (1) All switches and disconnects through which electric energy may be supplied to the particular section of line or equipment to be worked have been de-energized;
    • (2) All switches and disconnects are plainly tagged and/or locked indicating that persons are at work; and
    • (3) All switches and disconnects capable of being rendered inoperable are rendered inoperable.
  3. After all designated switches and disconnects have been opened, rendered inoperable, and tagged and/or locked, visual inspections must be conducted to ensure that equipment or lines are de-energized.
  4. Protective grounds must be applied on the disconnected equipment or lines to be worked on. > See Section 11.I.07.
  5. Guards or barriers must be erected as necessary to adjacent energized lines.
  6. When more than one crew requires the same line or equipment to be de-energized, a prominent tag and lock for each crew must be placed on the line or equipment by the Authorized Individual(s) holding the clearance(s) on said equipment or line.
  7. Upon completion of work on de-energized lines or equipment, each Authorized Individual holding a clearance must determine that all employees in the crew are clear and request a release of the clearance. The protective grounds installed will be removed. Authorized Individual will report to the GDA that all tags and locks protecting the crew may be removed.

11.I.05 When opening or closing a disconnect switch or circuit breaker on a power transmission/distribution line, exposure to potential explosion must be limited. Safe operating procedures must be established to minimize the risk of explosion.

11.I.06 When a crew working on a line or equipment can clearly see that the means of disconnecting from electrical energy are visibly open or visibly locked-out, the following provisions are required. > See Section 12.

  1. Guards or barriers must be erected as necessary to adjacent energized lines.
  2. Upon completion of work on de-energized lines or equipment, each designated person-in-charge must determine that all employees in the crew are clear that all protective grounds installed by the crew have been removed and must report to the GDA that all tags and locks protecting the crew may be removed.

11.I.07 Grounding.

  1. De-energized conductors and equipment that are to be grounded must be tested or visually checked by meters or indicators to be de-energized.
  2. Requirements as detailed in NEC and NESC for placing and removing protective grounds must be followed.
  3. Grounds must be placed between the work location and all sources of energy and as close as practicable to the work location, or grounds must be placed at the work location.
    • (1) 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 be worked on must be grounded at each work location.
    • (2) The minimum distance in Table 11-3 must be maintained from ungrounded conductors at the work location.
    • (3) Where the making of a ground is impractical, or the conditions resulting from it 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.
  4. Grounds may be temporarily removed only when necessary for test purposes and extreme caution must be exercised during the test procedures. The lines or equipment from which grounds have been removed must be considered energized.
  5. When grounding electrodes are used, such electrodes must have a resistance to ground of less than 25 ohms to remove the danger of harm to personnel or permit prompt operation of protective devices (NEC 250).
  6. Grounding to tower must be made with a tower clamp capable of conducting the anticipated fault current.
  7. All ground leads must be properly sized for the anticipated fault current, but must never be sized smaller than No. 2 AWG.

Knowledge Check Choose the best answer for the question.

11-8. How are de-energized conductors and equipment that are to be grounded checked to make sure they are deenergized?

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