What is a common feature of grounded structures in electrical installations?

Grounded structures in electrical installations are designed to ensure safety for human contact. Grounding provides a low-resistance path for electrical currents to travel to the ground in case of faults or short circuits. By safely directing any unintended electrical energy away from the structure and the people around it, grounded systems help reduce the risk of electric shock or electrocution.

In contrast, insulated structures are designed to prevent the flow of electricity, which is not the same as being grounded. While it's true that some grounded installations might conduct electricity in certain conditions (for instance, during a fault), the primary purpose of grounding is safety, not efficiency. Additionally, grounded structures are not typically temporary installations; they are often part of permanent safety measures in electrical systems. Therefore, the feature that stands out is their inherent safety for human contact when properly grounded.