Cables that enter flameproof or explosionproof enclosures must be sealed must be sealed:
These seals are required to complete the explosionproof or flameproof enclosure system.. This applies to both Zone 1 and Zone 2Zone 1 and Zone 2:
Cables in Zone 0 areas are required to be sealed at the first point of termination after crossing the Zone 0 classification boundary. Zone 0 areas are most likely to have gases or vapors present, so the cables must be sealed at terminations to keep gas and vapor out of the cables. The point of termination may be at an enclosure for intrinsically safe equipment, but will not usually be at flameproof or explosionproof enclosures because these protection methods are not permitted or required in Zone 0 areas, so explosionproof or flameproof enclosures could only contain intrinsically safe circuits if they were used.. Typically, where cables are terminated at flameproof or explosionproof enclosures, termination fittings include sealing provisions like the one shown here.

An explosionproof sealing fitting for Type MC-HL cable. (Courtesy of Cooper Crouse-Hinds)

NOTE: This is an unformatted excerpt from our online fire protection training library.