OSHA Electrical Hazards & Power Line Safety 1 — Questions and Answers
Question 1: What is the minimum safe approach distance required by OSHA for crane operations near power lines energized at 50 kV or less?
- 5 feet
- 10 feet (Correct answer)
- 15 feet
- 20 feet
Correct answer: 10 feet
OSHA 29 CFR 1926.1408 requires a minimum clearance of 10 feet for power lines energized up to 50 kV.
Question 2: Before beginning crane operations near overhead power lines, what must the crane operator or employer determine first?
- Whether the crane is insulated
- The voltage of the power lines (Correct answer)
- The weight of the suspended load
- Whether a signal person is available
Correct answer: The voltage of the power lines
The voltage must be determined first because minimum approach distances are calculated based on the power line's voltage level.
Question 3: If a crane boom accidentally contacts an energized overhead power line, what should the crane operator do immediately?
- Exit the cab as quickly as possible
- Stay in the cab and call for emergency help (Correct answer)
- Ask ground workers to push the boom away
- Lower the load to the ground and then exit
Correct answer: Stay in the cab and call for emergency help
The crane cab acts as a Faraday cage; exiting creates a path for current through the operator's body to ground, so staying inside is safer until power is deenergized.
Question 4: Which OSHA standard governs crane and derrick operations in construction, including power line safety requirements?
- 29 CFR 1926.502
- 29 CFR 1926.1400 (Subpart CC) (Correct answer)
- 29 CFR 1910.179
- 29 CFR 1926.550
Correct answer: 29 CFR 1926.1400 (Subpart CC)
29 CFR 1926.1400 (Subpart CC), effective 2010, is the comprehensive OSHA standard governing cranes and derricks in construction including electrical hazard requirements.
Question 5: What minimum clearance distance does OSHA require when crane operations are conducted near power lines energized between 350 kV and 1,000 kV?
- 10 feet
- 25 feet
- 35 feet (Correct answer)
- 50 feet
Correct answer: 35 feet
OSHA 1926.1408 requires a minimum approach distance of 35 feet for power lines energized between 350 kV and 1,000 kV.
Question 6: Which device can be installed on a crane to warn the operator when the equipment is approaching an energized power line?
- Anti-two-block device
- Load moment indicator
- Proximity alarm (warning device) (Correct answer)
- Rated capacity indicator
Correct answer: Proximity alarm (warning device)
A proximity alarm (also called a proximity warning device) alerts the operator with an audible or visual signal when the crane is nearing the power line danger zone.
Question 7: If the voltage of nearby overhead power lines cannot be determined, what minimum clearance distance must be maintained during crane operations?
- 10 feet
- 15 feet
- 20 feet (Correct answer)
- 25 feet
Correct answer: 20 feet
OSHA 1926.1408(b) requires a minimum clearance of 20 feet when the voltage cannot be determined, to account for uncertainty.
OSHA Electrical Hazards & Power Line Safety 1
What is the minimum safe approach distance required by OSHA for crane operations near power lines energized at 50 kV or less?