A wall for an electrical equipment enclosure includes an outer panel, an inner panel having a first side facing a chamber of the enclosure and a second side facing the outer panel, and at least one flange spaced apart from the outer panel and facing at least one peripheral portion of the inner panel and configured to prevent movement of the at least one peripheral portion of the inner panel towards the outer panel. The first panel is configured to press the at least one peripheral portion against the at least one flange responsive to pressure generated by an arc flash to form a seal between a periphery of the inner panel and the at least one flange that impedes passage of arc flash gases.