Cables with a gas/vapor-tight continuous sheath are exempt from sealing requirements unless what condition is true?

Cables that have a gas/vapor-tight continuous sheath are designed to prevent the ingress of hazardous gases or vapors, which is crucial in ensuring safety in explosive atmospheres. However, under certain circumstances, sealing requirements must still be implemented to maintain safety standards. When these cables are connected to process equipment that creates significant pressure, it indicates that the cable could potentially create a pathway for those hazardous substances to escape or enter the cable assembly, thereby compromising its integrity. This situation necessitates additional protective measures, which include sealing, to ensure that the hazardous materials do not enter the cable and present a risk of explosion or fire.

The other conditions listed do not meet the necessary criteria to override the exemption from sealing requirements. For example, whether the cables are insulated or uninsulated does not directly relate to the potential for hazardous gas or vapor escape in the same way as pressure does. Similarly, exposure to high temperatures or the length of the cables does not inherently create a risk that requires sealing unless it specifically pertains to the operation of connected equipment under pressure. Thus, it is the connection to process equipment with significant pressure that necessitates a reassessment of the sealing requirements, making it the correct condition for this exemption.