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Subchapter 5. Electrical Safety Orders
Group 2. High-Voltage Electrical Safety Orders
Article 36. Work Procedures and Operating Procedures
Group 2. High-Voltage Electrical Safety Orders
Article 36. Work Procedures and Operating Procedures
§2940.2. Minimum Approach Distances.
(a) The employer shall establish minimum approach distances using one of the following methods:
(1) Distances no less than computed by Table 2940.2-1 for AC Systems or Table 2940.2-6 for DC Systems using maximum anticipated per-unit transient overvoltage determined by an engineering analysis.
(A) No later than October 1, 2018 for voltages over 72.5 kilovolts, the employer shall determine the maximum anticipated per-unit transient overvoltage, phase-to-ground, through an engineering analysis.
When the employer uses portable protective gaps to control the maximum transient overvoltage, the value of the maximum anticipated per-unit transient overvoltage, phase-to-ground, shall provide for five standard deviations between the statistical spark over voltage of the gap and the statistical withstand voltage corresponding to the electrical component of the minimum approach distance. The employer shall make any engineering analysis conducted to determine maximum anticipated per unit transient overvoltage available upon request to employees and to the Chief of the Division or designee for examination and copying.
(2) The minimum approach distances in Table 2940.2-3, Table 2940.2-4, and the last row of Table 2940.2-6.
NOTE to subsection (a)(2): Approach distances in Table 2940.2-3 and Table 2940.2-4 assume a maximum anticipated per-unit transient overvoltage in Table 2940.2-5.
(A) Minimum approach distances shall be adjusted to account for work locations above 3,000 feet using altitude correction factors (Table 2940.2-7).
(3) Until October 1, 2018, employers may utilize the minimum approach distances specified in Appendix A, Table 6 or Tables 10 to 13.
(b) No employee shall be permitted to approach or take any conductive object without an approved insulating handle closer to exposed energized parts than the employer established minimum approach distances unless one of the following is met:
(1) The employee is insulated or guarded from the energized part (rubber insulating gloves or gloves with sleeves rated for the voltage involved shall be considered insulation of the employee from the energized part) upon which the employee is working provided that the employee has control of the part in a manner sufficient to prevent exposure to uninsulated portions of the employee's body), or
(2) The energized part is insulated or guarded from the employee and any other conductive object at a different potential.
(c) Type of Insulation.
(1) When an employee uses rubber insulating gloves as insulation from energized parts (under subsection (b)(1) of this section), the employer shall ensure that the employee also uses rubber insulating sleeves. However, an employee need not use rubber insulating sleeves if:
(A) Exposed energized parts on which the employee is not working are insulated from the employee; and
(B) When installing insulation for purposes of subsection (c)(1)(A) of this section, the employee installs the insulation from a position that does not expose his or her upper arm to contact with other energized parts.
(2) When an employee uses rubber insulating gloves or rubber insulating gloves and sleeves as insulation from energized parts under subsection (b)(1) of this section, the employer shall ensure that the employee:
(A) Puts on the rubber insulating gloves and sleeves in a position where he or she cannot reach into the minimum approach distance, established by the employer under Section 2940.2 of these Orders and
(B) Does not remove the rubber insulating gloves and sleeves until he or she is in a position where he or she cannot reach into the minimum approach distance, established by the employer under subsection (a).
(d) Working Position.
(1) When performing work with live line tools, minimum approach distances in accordance with subsection (a) shall be maintained. Conductor support tools, such as link sticks, strain carriers, and insulator cradles, shall be permitted to be used provided that the clear insulation is at least as long as the insulator string or the minimum approach distance specified in subsection (a).
Table 2940.2-1 AC Live-Line Work Minimum Approach Distance
The minimum approach distance (MAD; in meters) shall conform to the following equations.
For phase-to-phase system voltages of 601V to 5 kV:1 | |
MAD = M + D, where | |
D = 0.02 m | D is the electrical component of the minimum approach distance |
M = 0.31 m for voltages up to 750V and 0.61 m otherwise | M is the inadvertent movement factor |
For phase-to-phase system voltages of 5.1 kV to 72.5 kV:1 | |
MAD = M + AD, where | |
M = 0.61 m | M is the inadvertent movement factor |
A = the applicable value from 2940.2-7 | A is the altitude correction factor |
D = the value from 2940.2-2 corresponding to the voltage | |
and exposure or the value of the electrical component of the | |
minimum approach distance calculated using the method | |
provided in Appendix A to this article | D is the electrical component of the minimum approach distance |
For phase-to-phase system voltages of more than 72.5 kV, nominal:2 | |
MAD = 0.3048(C+a)VL-GTA+M, where | |
C = | 0.01 for phase-to-ground exposures that the employer can demonstrate consist |
only of air across the approach distance (gap), | |
0.01 for phase-to-phase exposures if the employer can demonstrate that no | |
insulated tool spans the gap and the no large conductive object is in the gap, or | |
0.011 otherwise | |
VL-G = | phase-to-ground rms voltage, in kV |
T = | maximum anticipated per-unit transient overvoltage; for phase-to-ground exposures, |
T equals TL-G, the maximum per-unit transient overvoltage, phase-to-ground, | |
determined by the employer under subsection (a)(1)(A) of this section; | |
for phase-to-phase exposures, T equals 1.35TL-G+0.45 | |
A = | altitude correction factor from 2940.2-7 |
M = | 0.31 m, the inadvertent movement factor |
a = | saturation factor, as follows: |
Phase-to-Ground Exposure | |||||
VPeak = TL-GVL-G√2 | 635 kV or less | 635.1 to 915 kV | 915.1 to 1,050 kV | More than 1,050 kV | |
a | 0 | (VPeak-635) / 140,000 | (VPeak-645) / 135,000 | (VPeak-675) / 125,000 | |
Phase-to-Phase Exposure3 | |||||
VPeak=(1.35TL-G+0.45) | |||||
VL-g√2 | 630 kV or less | 630.1 to 848 kV | 848.1 to 1,131 kV | 1,131.1 to 1,485kV | More than1,485 kV |
a | 0 | (VPeak-630) / 155,000 | (VPeak-633.6) / 152,207 | (VPeak-628) / 153,846 | (VPeak-350.5 / 203,666 |
1 Employers may use the minimum approach distances in Table 2940.2-3. If the worksite is at an elevation of more than 900 meters (3,000 feet), see footnote 1 to Table 2940.2-3.
2 Employers may use the minimum approach distances in Table 2940.2-4 except that the employer may not use the minimum approach distances in Table 2940.2-4 for phase-to-phase exposures if an insulated tool spans the gap or if any large conductive object is in the gap. If the worksite is at an elevation of more than 900 meters (3,000 feet), see footnote 1 to Table 2940.2-4. Employers may use the minimum approach distance in Table 6 through Table 13 in Appendix A to this article, which calculated MAD for various values of T, provided the employer follows the notes to those tables.
3 Use the equations for phase-to-ground exposures (with VPeak for phase-to-phase exposures) unless the employer can demonstrate that no insulated tool spans the gap and that no large conductive objects is in the gap.
)
)
1 Employers may use the minimum approach distances in this table provided the worksite is at an elevation of 900 meters (3,000 feet) or less. If employees will be working at elevations greater than 900 meters (3,000 feet) above mean sea level, the employer shall determine minimum approach distances by multiplying the distances in this table by the correction factor in Table 2940.2-7 corresponding to the altitude of the work.
2 For single-phase systems, use voltage-to-ground.
)
1 Employers may use the minimum approach distances in this table provided the worksite is at an elevation of 900 meters (3,000 feet) or less. If employees will be working at elevations greater than 900 meters (3,000 feet) above mean sea level, the employer shall determine minimum approach distances by multiplying the distances in this table by the correction factor in Table 2940.2-7 corresponding to the altitude of the work.
2 Employers may use the phase-to-phase minimum approach distances in this table provided that no insulated tool spans the gap and no large conductive object is in the gap.
3 The clear live-line tool distance shall equal or exceed the values for the indicated voltage ranges.
)
1 The distances specified in this table are for air and live-line tool conditions. If employees will be working at elevations greater than 900 meters (3,000 feet) above mean sea level, the employer shall determine minimum approach distances by multiplying the distances in this table by the correction factor in Table 2940.2-7 corresponding to the altitude of the work.
)
Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.
HISTORY
1. Amendment filed 12-10-87; operative 1-9-88 (Register 88, No. 1).
2. Amendment of subsection (b) and Table filed 12-12-94; operative 1-11-95 (Register 94, No. 50).
3. Editorial correction of Table (Register 95, No. 32).
4. Amendment of subsection (a)(1), table and table note filed 11-25-97; operative 12-25-97 (Register 97, No. 48).
5. Amendment filed 7-26-2000; operative 8-25-2000 (Register 2000, No. 30).
6. Amendment filed 4-28-2014; operative 7-1-2014 (Register 2014, No. 18).
7. Amendment of section heading and section filed 2-27-2018; operative 4-1-2018 (Register 2018, No. 9).
8. Amendment of Table 2940.2-1 filed 12-5-2019; operative 4-1-2020 (Register 2019, No. 49).
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