The term equipotential plane refers to installations in all of the following except?

The term "equipotential plane" is primarily used in electrical safety to refer to a condition where all exposed conductive parts are at the same electrical potential, minimizing the risk of electrical shock. This concept is particularly important in environments where water is present, as water can conduct electricity, creating potential hazards.

In swimming pools, natural and artificial bodies of water, and agricultural buildings, establishing an equipotential plane is crucial because these settings often involve water or moisture, which can conduct electricity and lead to dangerous situations if proper precautions are not taken. In these scenarios, the goal is to ensure that all conductive materials are bonded together to maintain a uniform potential, thereby protecting individuals from electric shock.

While aircraft hangars do have significant safety considerations given the presence of flammable materials and the operation of large equipment, the specific focus on equipotential planes is less prominent compared to environments like swimming pools or bodies of water. Aircraft hangars typically have different grounding and bonding requirements based on the aviation industry standards rather than focusing solely on the equipotential aspect. Thus, they do not fit the typical context of where equipotential planes are specifically emphasized, justifying why this is the exception among the other listed installations.