What precautionary measures must be taken before putting a loading crane into operation?

You answered correctly by selecting both "Secure the vehicle against tilting with the aid of the side supports" and "There must not be any electrical lines in the swivelling range."

Before operating a loading crane, it's important to stabilize the vehicle with side supports to prevent tipping over due to the crane's weight and movement. It is also essential to check for electrical lines in the area where the crane will operate, as contact with live wires can cause serious accidents or electrocution. These two measures help ensure the safety of both the operator and others nearby.

Option 3 is not strictly required in every situation because you typically always need to secure the vehicle against tilting, not just check if it is necessary. Remember to always stabilize the crane and check for overhead obstacles, particularly electrical lines, every time before operation.