When signaling a crane lifting a personnel platform, which device must be attached to the crane?

When signaling a crane lifting a personnel platform, it is essential for the crane to be equipped with an anti two-block device. This device is crucial as it prevents the two-block condition, which occurs when the hoisting block and the boom tip accidentally come into contact with each other during operations. This situation can cause significant damage to the crane and pose serious safety risks to personnel working on the platform.

The anti two-block device serves as a safety mechanism designed to halt the lift if the block approaches the boom, thereby preventing potential accidents that could result from improper clearances. This safety feature is particularly important when lifting personnel, as it helps to ensure that workers on the platform are not exposed to hazards that could arise from equipment malfunction.

In contrast, while other options may be relevant in different contexts, they do not specifically address the critical safety aspect associated with lifting personnel platforms. A load limiter monitors and restricts the load capacity, an emergency stop switch allows for manual disconnection of power in emergencies, and a safety harness protects individual workers but does not manage the crane's operational safety regarding two-block conditions.