Patent ID: 8492662

Claim:
An arc resistant enclosure for a dry type transformer, comprising: a base structure; a dry-type transformer seated on the base structure; at least three walls secured to the base structure, forming an enclosed space for housing the transformer, wherein one of the walls comprises a first and second corner piece and at least one face frame defining an access opening and wherein the at least one face frame is proximate the first and second corner pieces; an access panel covering the access opening, wherein the access panel contains at least one ventilation grating having an arc fault damper apparatus affixed adjacent thereto; a roof structure secured to the walls; at least one ventilation opening in either the roof or walls; wherein an arc fault damper apparatus is affixed adjacent at least one of the at least one ventilation gratings, with the proviso that an arc fault damper apparatus is affixed adjacent every ventilation grating that is located at or below a height of 79 inches from the floor level, and wherein each arc fault damper apparatus is configured to close upon an arc flash event, thereby substantially preventing the escape of arc flash gas through the at least one ventilation gratings.