Hazard Identification and Power Line Safety Flashcards

A crane operator is working near a 345 kV transmission line. The employer has not obtained voltage information from the utility owner. Under OSHA 1926.1408, what minimum clearance must the operator maintain?

Answer: 50 feet

Under OSHA 1926.1408 Table A, when voltage is unknown or not determined, the default minimum clearance is 50 feet. This conservative default protects workers when voltage information has not been obtained from the utility owner/operator prior to work.

During a lift near an energized 69 kV line, the load line momentarily enters the minimum approach distance. The qualified electrical worker on site says it is acceptable because the contact was brief. Which statement is correct?

Answer: The worker is incorrect — any encroachment into the minimum approach distance requires immediate work stoppage and incident review regardless of duration

OSHA 1926.1408 does not provide any exemption for brief or transient encroachments into the minimum approach distance. Any encroachment is a violation that requires immediate work stoppage, de-energization or re-route assessment, and incident documentation. Duration is irrelevant to the regulatory requirement.

A crane is being used on a jobsite where an insulating link (proximity alarm + insulating link combination) has been installed. Which of the following statements about insulating links under OSHA 1926.1408 is accurate?

Answer: An insulating link is a supplemental protective measure and does NOT allow encroachment past the Table A distances unless voltage has been confirmed and additional employer/utility controls are in place

An insulating link is a supplemental protective device, not a blanket authorization to work within minimum approach distances. OSHA 1926.1408 specifies that reduced clearances only apply when the utility has de-energized and visibly grounded the line, or when both employer and utility have established alternative protective measures per an engineered plan. An insulating link alone does not satisfy those requirements.

A steel erection crew asks a crane operator to work under an energized 25 kV distribution line using the 'encroachment prevention' option (no utility de-energization). The employer provides a spotter, proximity alarm, and a dedicated signal person. Under OSHA 1926.1408(b)(4), what additional requirement must be met to work in the zone between 20 feet and the Table A minimum approach distance?

Answer: Establishment of a dedicated spotter who has no other duties and can communicate directly with the operator at all times

Under OSHA 1926.1408(b)(4), using encroachment prevention methods requires that a dedicated spotter be stationed with an unobstructed view of the lines and the equipment, able to communicate directly and continuously with the operator. The spotter must have no other assigned duties during this operation. This is a specific, mandatory requirement distinct from a general signal person.

A mobile crane with a 150-foot boom is traveling on a public road when the operator notices a distribution line crossing the road ahead. The boom is lowered but the total height clearance to the line is 14 feet and the line voltage is marked as 7.2 kV phase-to-ground. What is the CORRECT action?

Answer: Stop and verify actual clearance with a measuring instrument; proceed only if the NESC minimum vertical clearance plus the required OSHA approach distance is satisfied

During transit, OSHA 1926.1411 requires that minimum clearances from 1926.1408 Table A still be maintained. A 7.2 kV phase-to-ground line is approximately 12.5 kV phase-to-phase, requiring 10 feet of clearance under Table A. However, the operator must confirm actual clearance with a measurement — visual estimation from the cab is unreliable and the NESC road-crossing requirements may impose additional vertical clearance minimums. Proceeding without verification violates both OSHA and safe operating practice.

An operator receives a signal to begin a pick, but notices the load path will pass within 30 feet of a 230 kV transmission line. The site's pre-work utility survey shows the line is owned by a utility that has not responded to the employer's coordination request. What is the operator's correct course of action under OSHA 1926.1407–1408?

Answer: Refuse to make the lift until the utility responds, the line is de-energized, or a qualified engineer confirms clearances and protective controls are in place

For a 230 kV line, Table A requires a minimum approach distance of 20 feet; however, the employer is also required under 1926.1407 to determine the voltage by contacting the utility. If the utility has not responded, the unknown-voltage default of 50 feet applies — meaning 30 feet of clearance is actually insufficient. The operator must refuse the lift. A signal person's visual observation and mere notification to the utility do not satisfy OSHA's requirements when voltage has not been confirmed.