Allied Encyclopedia: Insulation Shrinkback

Insulation shrinkback can increase the risk of wire shorts and destroy the protective seal that the insulation and jacketing are designed to provide. We know these are important problems to avoid, but what is insulation shrinkback and how can we prevent it? Here are answers to some common questions about shrinkback.

What is shrinkback?
Shrinkback occurs when a cable’s insulation pulls away from a termination connector or cable splice. When it pulls back, it increases the insulation clearance or the distance between the end of the insulation and the termination device. Increased insulation clearance leaves part of the conductor exposed. As a result, there is a higher risk for shorting as well as a compromised seal which can now let dirt and water into the cable. These are damaging factors that can cost you a lot of time and money in cable replacements.

What causes insulation shrinkback?
Shrinkback is a result of mechanical stress involved with the manufacturing process. If materials are extruded at even slightly different speeds, it can cause the insulation material to stretch. Once the cable is then cut to size, the insulation will automatically return to its true size if friction isn’t enough to hold it in place around the conductor. High temperatures and exposure to a wide temperature range can cause shrinkback to occur more rapidly.

How do we prevent shrinkback?
Although it may seem like shrinkback is unavoidable, there are several things you can do to minimize its effects. First, you can choose materials that are less likely to experience shrinkback. You can also check out shrinkback testing and standards developed by the American National Standards Institute (ANSI) and the Insulated Cable Engineers Association (ICEA) and then include shrinkback requirements when placing your cable order. Finally, you can use insulation support crimps when splicing or terminating your wire.

Use this knowledge to defend yourself against shrinkback problems in your future wire and cable jobs. Preventing problems like these are the key to finding cable that will last for a long time in your application.

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