Jackets aren't just for cold weather
Since we took a break from blogging last week to fill up on holiday meals, I thought our next Back to Basics blog should bring us back to the beginning of wire and cable 101. Similar to our human needs to stay warm, dry, and protected from harsh environmental elements, cables need jackets as well - proving to be another example that the cable industry isn’t total unrelated to us humans.
A cable jacket is defined as the outer covering that is typically placed around a group of insulated conductors, pairs, triads, or other cable core components to provide mechanical protection, as well as to aid in cable installations. Jacket materials can be identical to the insulation materials as they both protect the conductors, so in order to save some time we will only review the most widely used and practical jacket materials.
PVC: PVC jackets can usually be made to be UV resistant, oil resistant, and flame retardant, making PVC a good jacket for general use. In order for PVC to be a useful jacket, vinyl resin must be blended with other ingredients due to the fact that vinyl resin alone is extremely rigid and can be subjected to degradation at processing temperatures. Therefore, the ingredients added to the vinyl resin determine which properties the finished PVC product will have.
Polyethylene (PE): PE is a good jacket to use in wet locations such as direct burial applications. PE can be foamed, solid or cross-linked. Some solid forms include linear low- density PE, low density PE, medium density PE, and high density PE.
Thermoplastic Elastomer (TPE): TPE has a temperature range of -60 C to 125C. It is resistant to fuels, oils, solvents, water, and can be made highly flame resistant. TPE has low corrosive outgassing by products are is acid and alkali resistant.
Thermoplastic Polyurethane (TPU): TPU is also resistant is fuels, oils, solvents, and water. It has 2x the tensile strength of and 3x the tear abrasion resistance of PVC. TPU is well known for its mechanical properties such as abrasion resistance and weatherability.
Low Smoke Zero Halogen (LSZH): This jacket material produces little or no smoke when burned. The zero halogen part of the name describes the lack of elements from the halogen group on the periodic table (chlorine, fluorine, etc.). LSZH jackets are frequently required in military and mass transit applications or any application that is human-interfacing.