- Part Number:1926
- Part Number Title:Safety and Health Regulations for Construction
- Subpart:1926 Subpart V
- Subpart Title:Electric Power Transmission and Distribution
- Standard Number:
- Title:Working on or near exposed energized parts.
- GPO Source:
Note to paragraph (c)(1)(ii): See Appendix B to this subpart for information on how to calculate the maximum anticipated per-unit transient overvoltage, phase-to-ground, when the employer uses portable protective gaps to reduce maximum transient overvoltages.
Note 1 to paragraph (g)(2): Appendix E to this subpart provides guidance on estimating available heat energy. The Occupational Safety and Health Administration will deem employers following the guidance in Appendix E to this subpart to be in compliance with paragraph (g)(2) of this section. An employer may choose a method of calculating incident heat energy not included in Appendix E to this subpart if the chosen method reasonably predicts the incident energy to which the employee would be exposed.
Note 2 to paragraph (g)(2): This paragraph does not require the employer to estimate the incident heat energy exposure for every job task performed by each employee. The employer may make broad estimates that cover multiple system areas provided the employer uses reasonable assumptions about the energy-exposure distribution throughout the system and provided the estimates represent the maximum employee exposure for those areas. For example, the employer could estimate the heat energy just outside a substation feeding a radial distribution system and use that estimate for all jobs performed on that radial system.
Note to paragraph (g)(3): This paragraph prohibits clothing made from acetate, nylon, polyester, rayon and polypropylene, either alone or in blends, unless the employer demonstrates that the fabric has been treated to withstand the conditions that may be encountered by the employee or that the employee wears the clothing in such a manner as to eliminate the hazard involved.
Note to paragraph (g)(4)(iii): This paragraph does not apply to conductors that are capable of carrying, without failure, the maximum available fault current for the time the circuit protective devices take to interrupt the fault.
Note to paragraph (g): See Appendix E to this subpart for further information on the selection of appropriate protection.
The employer shall ensure that devices used by employees to close circuits under load conditions are designed to safely carry the current involved.
Table V-2 - AC Live-Line Work Minimum Approach Distance | |||||
The minimum approach distance (MAD; in meters) shall comform to the following equations. | |||||
For phase-to-phase system voltages of 50 V to 300 V: 1 | |||||
MAD = avoid contact | |||||
For phase-to-phase system voltages of 301 V to 5kV: 1 | |||||
MAD = M + D, where | |||||
D = 0.02 m | the electrical component of the minimum approach distance | ||||
M = 0.31 m for voltages up to 750V and 0.61 m otherwise | the inadvertent movement factor | ||||
For phase-to-phase system voltages of 5.1 kV to 72.5V: 1,4 | |||||
MAD = M + AD, where | |||||
M = 0.61 m | the inadvertent movement factor | ||||
A = the applicable value from Table V-4 | the altitude correction factor | ||||
D = the value from Table V-3 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 B to this subpart | the electrical component of the minimum approach distance | ||||
For phase-to-phase system voltages of more than 72.5 kV, nominal: 2, 4 | |||||
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 paragraph (c)(1)(ii) of this section; for phase-to-phase exposures, T equals 1.35TL-G+0.45 | ||||
A = | altitude correction factor from Table V-4 | ||||
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-Ground 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 1,485 kV | More than 1,485 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 V-5. If the worksite is at an elevation of more than 900 metes (3,000 feet), see footnote 1 to Table V-5
2 Employers may use the minimum approach distances in Table V-6, except that the employer may not use the minimum approach distances in Table V-6 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 (3,00 feet), see footnote 1 to Table V-6. Employers may use the minimum approach distance in Table 7 through Table 14 in Appendix B to this subpart, 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.
4 Until March 31, 2015, employers may use the minimum approach distances in Table 6 in Appendix B to this subpart
TABLE V-3-ELECTRICAL COMPONENT OF THE MINIMUM APPROACH DISTANCE (D; IN METERS) AT 5.1 TO 72.5 KV | ||
Nominal voltage (kV) phase-to-phase | Phase-to-ground exposure | Phase-to-phase exposure |
D (m) | D (m) | |
5.1 to 15.0 ............................................................................................................................... | 0.04 | 0.07 |
15.1 to 36.0 ............................................................................................................................. | 0.16 | 0.28 |
36.1 to 46.0 ............................................................................................................................. | 0.23 | 0.37 |
46.1 to 72.5 ............................................................................................................................. | 0.39 | 0.59 |
TABLE V-4-ALTITUDE CORRECTION FACTOR | |
Altitude above sea level (m) | A |
0 to 900 ................................................................................................................................................................................ | 1.00 |
901 to 1,200 ......................................................................................................................................................................... | 1.02 |
1,201 to 1,500 ...................................................................................................................................................................... | 1.05 |
1,501 to 1,800 ...................................................................................................................................................................... | 1.08 |
1,801 to 2,100 ...................................................................................................................................................................... | 1.11 |
2,101 to 2,400 ...................................................................................................................................................................... | 1.14 |
2,401 to 2,700 ...................................................................................................................................................................... | 1.17 |
2,701 to 3,000 ...................................................................................................................................................................... | 1.20 |
3,001 to 3,600 ...................................................................................................................................................................... | 1.25 |
3,601 to 4,200 ...................................................................................................................................................................... | 1.30 |
4,201 to 4,800 ...................................................................................................................................................................... | 1.35 |
4,801 to 5,400 ...................................................................................................................................................................... | 1.39 |
5,401 to 6,000 ...................................................................................................................................................................... | 1.44 |
TABLE V-5-ALTERNATIVE MINIMUM APPROACH DISTANCES FOR VOLTAGES OF 72.5 KV AND LESS 1 | ||||
Nominal voltage (kV) phase-to-phase | Distance | |||
Phase-to-ground exposure | Phase-to-phase exposure | |||
m | ft | m | ft | |
0.050 to 0.300 2 ..................................................................................................... | Avoid contact | Avoid contact | ||
0.301 to 0.750 2 ............................................................................................... | 0.33 | 1.09 | 0.33 | 1.09 |
0.751 to 5.0 ..................................................................................................... | 0.63 | 2.07 | 0.63 | 2.07 |
5.1 to 15.0 ....................................................................................................... | 0.65 | 2.14 | 0.68 | 2.24 |
15.1 to 36.0 ..................................................................................................... | 0.77 | 2.53 | 0.89 | 2.92 |
36.1 to 46.0 ..................................................................................................... | 0.84 | 2.76 | 0.98 | 3.22 |
46.1 to 72.5 ..................................................................................................... | 1.00 | 3.29 | 1.20 | 3.94 |
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 V-4 corresponding to the altitude of the work.
2 For single-phase systems, use voltage-to-ground.
TABLE V-6-ALTERNATIVE MINIMUM APPROACH DISTANCES FOR VOLTAGES OF MORE THAN 72.5 KV 1, 2, 3 | ||||
Voltage range phase to phase (kV) | Phase-to-ground exposure | Phase-to-ground exposure | ||
m | ft | m | ft | |
72.6 to 121.0 ................................................................................................... | 1.13 | 3.71 | 1.42 | 4.66 |
121.1 to 145.0 ................................................................................................. | 1.30 | 4.27 | 1.64 | 5.38 |
145.1 to 169.0 ................................................................................................. | 1.46 | 4.79 | 1.94 | 6.36 |
169.1 to 242.0 ................................................................................................. | 2.01 | 6.59 | 3.08 | 10.10 |
242.1 to 362.0 ................................................................................................. | 3.41 | 11.19 | 5.52 | 18.11 |
362.1 to 420.0 ................................................................................................. | 4.25 | 13.94 | 6.81 | 22.34 |
420.1 to 550.0 ................................................................................................. | 5.07 | 16.63 | 8.24 | 27.03 |
550.1 to 800.0 ................................................................................................. | 6.88 | 22.57 | 11.38 | 37.34 |
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 V-4 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.
TABLE V-7-DC LIVE-LINE MINIMUM APPROACH DISTANCE (IN METERS) WITH OVERVOLTAGE FACTOR 1 | |||||
Maximum anticipated per-unit transient overvoltage | distance (m) maximum line-to-ground voltage (kV) | ||||
250 | 400 | 500 | 600 | 750 | |
1.5 or less ............................................................................ | 1.12 | 1.60 | 2.06 | 2.62 | 3.61 |
1.6 ........................................................................................ | 1.17 | 1.69 | 2.24 | 2.86 | 3.98 |
1.7 ........................................................................................ | 1.23 | 1.82 | 2.42 | 3.12 | 4.37 |
1.8 ........................................................................................ | 1.28 | 1.95 | 2.62 | 3.39 | 4.79 |
1 The distances specified in this table are for air, bare-hand, 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 V-4 corresponding to the altitude of the work.
TABLE V-8-ASSUMED MAXIMUM PER-UNIT TRANSIENT OVERVOLTAGE | ||
Voltage range (kV) | Type of current (ac or dc) | Assumed maximum per-unit transient overvoltage |
72.6 to 420.0 ............................................................................................................................ | ac | 3.5 |
420.1 to 550.0 .......................................................................................................................... | ac | 3.0 |
550.1 to 800.0 .......................................................................................................................... | ac | 2.5 |
250 to 750 ................................................................................................................................ | dc | 1.8 |
[79 FR 20702-20708, July 10, 2014; 79 FR 56962, September 24, 2014; 80 FR 60040, October 5, 2015]