By what percentage should crane capacity be reduced?

• A. 10%
• B. 25%
• C. 50%
• D. 75%

Answer: (C)

Crane capacity isn’t fixed for every lift; it depends on setup conditions such as ground stability, outrigger deployment, radius, boom angle, and any wind or rigging effects. When conditions aren’t ideal, you derate the capacity to keep the machine stable and prevent tipping or dynamic overloads. In many safety manuals and practice tests, a 50% reduction is used as a conservative rule of thumb to cover these uncertainties. So, applying a half-capacity derate provides a safe margin for typical non-ideal setups. Always verify against the crane’s actual load chart for the specific radius, configuration, and site conditions.