When can a worker aloft establish a grounding scheme without a connection to earth?

The correct choice is grounded in the understanding of grounding schemes in electrical work. Establishing a grounding scheme without a direct connection to earth can be permissible if the grounding equipment is correctly sized to handle any potential faults or surges that could occur while working aloft. Correct sizing of the grounding equipment ensures that it can adequately dissipate any electrical energy that may arise, thus maintaining safety standards.

For instance, if a worker is properly equipped with a grounding scheme that incorporates insulation and is designed for the specific voltage level they are working with, they can remain safe even without a traditional earthing connection.

This scenario aligns with safety practices in electrical work, focusing on the effectiveness of the grounding equipment rather than requiring a direct connection to ground to minimize electrical hazards. In contrast, the other options lack this crucial safety criterion and do not adequately address the requirements for grounding in that scenario.