Which of the following types of installations is NOT covered under NEC Article 680?

The type of installation that is not covered under NEC Article 680 is bathtubs. Article 680 of the NEC specifically focuses on the electrical installations associated with swimming pools, fountains, and hot tubs, which are all considered as types of 'pools' under the definitions provided in the code. These installations involve aspects that require specialized electrical safety measures due to the presence of water and the increased risk of electric shock or other hazards.

Bathtubs, while they may have water, do not fall under the same category as the aforementioned installations in terms of electrical requirements. The code addresses environments where large volumes of water or special features like jets and lighting installations create specific safety concerns that are not applicable in the same way to bathtubs. As a result, bathtubs are excluded from the requirements set forth in Article 680, focusing instead on those installations that present unique electrical safety challenges due to their use and accessibility.