What is a limitation of crane-mounted safety devices like boom guards and proximity devices?

A limitation of crane-mounted safety devices such as boom guards and proximity devices is that they may not function effectively in high-voltage areas. This is due to the potential interference that high voltage can have on the electronic components of the safety devices. In environments with heightened electrical risks, the reliability of these devices can be compromised, which can jeopardize the safety they are designed to enhance.

Other options suggest misunderstandings about the role of these safety devices. For instance, they are meant to complement, not replace, safe operator practices—highlighting that operator training and adherence to safety protocols are still essential. Additionally, while these devices contribute to safety, they do not provide a guarantee of protection for ground personnel, as they are only one part of an overall safety strategy. Lastly, many crane-mounted safety devices require a power source to function properly, meaning their operation is contingent on having adequate power rather than being independent of it.