NCCCO Mobile Crane Operator 5

Question 1

Under ASME B30.5, at what minimum distance from electrical power lines rated up to 50 kV must a crane boom maintain clearance?

Accepted Answer

10 feet

Answer

ASME B30.5 and OSHA 1926.1408 require a minimum 10-foot clearance for power lines rated up to 50 kV.

Question 2

When traveling a mobile crane with a load suspended, the operator must:

Accepted Answer

Follow the manufacturer's procedures and the lift director's direction, keeping the load as low as practical

Answer

Traveling with a suspended load requires manufacturer guidance, supervisor oversight, and the load kept low to reduce swing and instability.

Question 3

A wire rope's discard criteria include finding how many broken wires in one lay length for a running rope?

Accepted Answer

6 broken wires in one lay length or 3 in one strand

Answer

Per ASME B30.5, a running wire rope must be removed from service if 6 or more broken wires are found in one lay length, or 3 in a single strand.

Question 4

What is the primary purpose of an anti-two-block (ATB) device?

Accepted Answer

Automatically stops the hoist and boom functions before two-blocking can occur

Answer

An ATB device detects when the hook block is dangerously close to the boom tip and automatically disables hoist-up and boom-down functions.

Question 5

Which factor does NOT directly affect a mobile crane's rated lifting capacity at a specific radius?

Accepted Answer

The color of the load being lifted

Answer

Rated capacity depends on radius, boom length, reeving, and outrigger configuration—the physical properties of the load, not its color.

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