DEFORMING PRESSURE RING SEAL FOR AN ARC-RESISTANT SWITCHGEAR DUCT

An electrical enclosure assembly includes a duct chamber with two adjacent duct sections having respective first and second flanges fastened to form a flanged butt joint. The duct sections are in a path through which a pressure wave travels during an arc-fault event from an arc-fault device to an exhaust vent. A pressure ring is fastened internally to at least one of the first and second panels to cover the flanged butt joint. In response to a peak pressure of the pressure wave, the pressure ring deforms with the respective adjoining panels of the duct sections. Although the peak pressure creates gaps in the flanged butt joint, the deformation causes the pressure ring to fill-in those gaps and, thus, block ventilation through the flanged butt joint.