FREE NCCCO Power Line Hazard Identification and Safety Procedures Questions and Answers

Question 1

According to OSHA 1926.1408, what is the minimum required clearance for a crane operating near a power line with a voltage of up to 50kV?

Accepted Answer

10 feet

Answer

OSHA's Table A in standard 1926.1408 specifies minimum clearance distances based on voltage. For power lines with a voltage up to 50,000 volts (50kV), the standard minimum clearance is 10 feet to prevent arcing and ensure a safe buffer zone.

Question 2

If a crane's boom or load line makes contact with an energized power line, what is the safest immediate action for the operator?

Accepted Answer

Remain in the cab and try to break contact.

Answer

The safest place for the operator is inside the cab, as the crane and the ground around it will be energized. Exiting the cab can cause electrocution due to step potential or touch potential. The operator should stay put, warn others to stay away, and attempt to break contact by moving the crane away from the line if possible.

Question 3

Who is responsible for determining a power line's voltage to establish the correct minimum approach distance?

Accepted Answer

The utility owner/operator.

Answer

The crane operator or employer cannot guess the voltage of a power line. They must assume it is energized and contact the utility owner/operator to verify the exact voltage, which is then used to determine the required clearance from OSHA's Table A.

Question 4

What is 'step potential' in the context of a crane contacting a power line?

Accepted Answer

The voltage difference between a person's two feet on energized ground.

Answer

When a crane contacts a power line, the electricity flows through the crane into the ground, creating a voltage gradient. 'Step potential' is the dangerous voltage difference between a person's two feet as they walk in this energized zone, which can cause a fatal electric shock to pass through the body.

Question 5

If crane work must be performed closer than the minimum permitted distance in OSHA Table A, what is the primary requirement?

Accepted Answer

The power line must be de-energized and visibly grounded.

Answer

Working inside the minimum approach distance is extremely hazardous and is only permitted under strict controls. The most fundamental requirement is that the utility owner/operator must de-energize and visibly ground the power line to remove the electrical hazard entirely.

NCCCO (National Commission for the Certification of Crane Operators) Practice Test

NCCCO (National Commission for the Certification of Crane Operators) Practice Test

FREE NCCCO Power Line Hazard Identification and Safety Procedures Questions and Answers