All lifting devices are load tested to what percentage of their rated capacity?

• A. 100%
• B. 110%
• C. 125%
• D. 150%

Answer: (C)

Proof testing of lifting devices is performed with a load greater than the rated capacity to verify strength and safety margins. The standard practice is to apply a test load of 125% of the rated capacity and hold it for a specified duration. This provides a built-in buffer to account for dynamic effects, shock loads, rigging variations, and measurement tolerances, ensuring the equipment can handle overload conditions without permanent deformation or failure. If the device withstands this 125% load and remains within allowable limits, it demonstrates that the equipment is safe to operate at its rated capacity under normal use. Choosing 100% wouldn’t test the extra margin needed for real-world conditions, 110% offers too little additional safety, and 150% is more than typically required by standards.