An apprentice lineman was electrocuted in New Jersey when the 45-foot-long pole he was grasping adjacent to a substation contacted an overhead transmission line. This event was attributable to an unusual number of departures from normal, safe construction practice. This article reviews the rules that were not followed, and explains how failure to do so contributed to the accident.
A project was in progress for installing a 12 kV distribution feeder line from a substation. A line of utility poles was being installed, running outside and parallel to the substation’s fence. A digger-derrick had finished digging a hole into which a 45-foot pole was to be set. A commercial truck parked in the line-of-sight obstructed the derrick operator’s view of the hole, and its owner could not be located in order to ask him or her to move it. The utility pole was then suspended from the derrick’s load line. As it was being moved by the derrick and guided by hand at the butt end by the apprentice lineman toward the freshly-dug hole, the pole made contact with an overhead 69 kV transmission line, and he was electrocuted.
In connection with the planning for this project, no information for depicting work site hazards, such as nearby energized overhead lines, appeared on any job orders, drawings, or sketches. If such requirements had existed, the crew would have been better able to understand the nature of this hazard and to arrange mitigation methods. OSHA Subpart V, CFR 1926.950(b)(1) required that the work site be inspected before the work commenced and that the location of electrical lines and equipment be noted.
The utility’s safety rules required that the location of the new pole be clear of obstructions as viewed from the operator’s station of the pole-setting derrick, so that pole setting could be accomplished “without interference.”
However, the work proceeded with the derrick operator having an obstructed view of the work site. The optimum position of the derrick for conducting and supervising the pole-setting procedure was not achieved because of the presence of the parked truck. In particular, the derrick operator did not have a direct view of the butt of the pole during the setting procedure. There was no urgency to the pole-setting procedure that required the work to proceed under this handicap.
No member of the crew had been designated with the sole job of observing equipment clearance and giving warning, in violation of OSHA Subpart N, 29 CFR 1926.550(a)(15)(iv), particularly with the derrick operator’s visibility compromised. If such an observer had been present, especially assigned to warn crew members of electrical and other work site hazards, the accident is much less likely to have occurred, since the proximity of the suspended pole to the overhead 69 kV line would have been noted.
The pole that was to be set in the ground was being raised and moved by a steel load line and “choker,” which was wrapped around the pole. However the “choker” was set too low on the “pick-point” of the pole, and not in accordance with good construction practice. Accord-ingly, the pole’s center of gravity was too far above the “pick point” and the apprentice lineman did not have adequate control of the pole suspended from the derrick arm, thus contributing to the accident.
The lifting equipment was required to be bonded to an effective ground, particularly since it was being operated adjacent to an energized substation. No grounding conductor from the derrick truck nor any grounding rod was noted in the accident report or in after-accident photographs. Although the derrick’s outriggers were down, they were set on wood blocks, thus providing very poor grounding. If a grounding conductor and ground rod had been set, the conductive steel lifting cable would have been brought to a much lower potential than that of the overhead 69kV line that was contacted by the pole. This would have substantially increased the apprentice lineman’s survival prospects. Grounding is required by OSHA 29 CFR 1926.955(a)(6)(ii).
Use of a nonconductive tag line was required by OSHA 29 CFR 1926.953(d), because of the distinct possibility that the pole being hoisted and moved might contact an energized line. No significant shock would have been experienced if a tag line had been employed.
Because the new utility pole, although freshly treated and moist, formed part of the electrical shocking circuit and offered considerable electrical resistance, the apprentice lineman experienced a markedly reduced voltage across his body. The report of a “fuzz” type sound by eyewitnesses at the time of contact, rather than a sharp, short duration sound, is consistent with a high-resistance, low-current contact. Thus he suffered primarily electro-thermal burns, not high-voltage arcing burns. He initially experienced ventricular fibrillation, which is typical of lower-voltage shocks, rather than immediate cardiac arrest, which is more typical of higher-voltage shocks.
Utility practices and OSHA Rule Subpart V, 29 CFR 1926,952(c) called for a clearance of 3 feet (Table V-1) as a “minimum working and clear hot stick distance,” where a derrick operates proximate to 69 kV power lines, provided that those lines were being worked on. However, if they were not being worked on, and were instead merely hazardous obstructions to the work in progress, then Subpart N, OSHA 29 CFR 1926.550(a)(15)(ii), “Cranes and Derricks” applied instead. This Rule required a minimum working distance of 10.6 feet from the suspended pole to the 69kV line.
OSHA 29 CFR 1926.955(b)(5)(iii) required that pole setting be done with the overhead transmission line dead, if practical. Neither service requirements nor any emergency made de-energizing the line impractical. Possible requirements for de-energizing the transmission line were not included in the work plan, nor was the line’s presence noted. Downtime duration while installing two 45-foot poles would have been minimal. Alternately, the substation could have been supplied by switching over without any outage being required to another 69kV feeder that was located nearby with adequate clearance.
In summary, the major lack of electrical worker safety planning for this project included shortcomings such as:
* No written criteria for when to de-energize in working situations was provided.
* No tailgate or similar prework conferences among workmen to review job site hazards were held.
* Clearance data relative to the 69kV lines were not provided.
* Initial inspections of nearby energized lines during planning for distribution line planning were not conducted.
Thus a substantial number of electrical safety methods and devices were required, which should have corresponded to the 69 kV hazard, rather than to 12 kV, which was the voltage of the unenergized system during installation. Given the great number of breaches of safety rules that should have been observed as required by circumstances, and the lack of any sudden, unforeseeable factors that might affect work site safety (e.g., weather), there was a high probability that this accident was going to occur.
MAZER is a consulting electrical engineer who currently specializes in electrical safety issues. His telephone number is (202) 338-0669, and his e-mail address is email@example.com.