Abstract: An enclosure for electrical equipment is arranged in sections, typically vertical and with an equipment mounting section at the front and an air passage section at the rear. Air is constantly circulated through the two sections, in a closed loop, to maintain an even temperature and avoid hotspots in the enclosure. At the top, one or more fans are positioned over each section, and an air inlet and an air outlet are provided. A pivotal baffle has two positions. In one it shuts off access to the inlet and outlet and permits the closed circulation of air. In the other position it shuts off circulation between sections at one end and opens access to the inlet and outlet, giving an air circulation from the inlet, through the sections and out of the outlet. An additional fan can be switched on for the latter form of circulation.