The increasing numbers of engineers and consultants have accepted the effectiveness of heat shrink technology to secure electrical installations; they are in favor of embracing heat shrink tubes at least in middle to large electrical installations. When the manufacturers of heat shrink sleeves are expanding their product line to facilitate the users, the first time users still have some clouds over their inclination towards using heat shrink tubes or sleeves. The success of getting the ultimate results as you expect by using the most advanced electrical insulation technology depends upon choosing the right shrink ratio, diameter, & length of heat shrink tubes or sleeves.

Shrink Ratio of Heat Shrink Tubes: Heat shrink tubes are manufactured to give 2:1 or 3:1 shrink ratios. It means the heat shrink tube expands two or three times on being heated. When the tubes are shrunk, it is considered in the recovered state. The 2:1 shrink ratio of heat shrink tubes is good for jacketing wire bundles or harnesses. The 3:1 ratio is good to seal irregular shapes. Both the heat shrink tubes of2:1 and 3:1 shrink ratios are available in single wall tubing and dual wall tubing structures.

Diameter of Heat Shrink Sleeves: The ideal recovered diameter of the underlying cables should be measured at the widest part. The ideal heat shrink tubes would be of 20% – 30% larger diameter. The internal and outer diameters are listed in the data sheets; you should focus more on the internal diameter of heat shrink tubes to get the best fit insulation solution.

Length of Heat Shrink Tubes: The length of heat shrink tubes is associated with longitudinal shrinkage. Heat shrinkable sleeves shrink in length also during the recovery process. Focus on the change in length after recovery stage. Longitudinal shrinkage in heat shrink sleeves varies from 5% to 10%; and, it depends upon the tube material.

Which heat shrink tubing should you choose- Single Wall vs. Dual Wall Tubing:  The heat shrink tubes are being used to address multiple diverse concerns like strain relief, insulation, cosmetic, sealing, and protection. Dual wall shrink tubes work for all of these concerns but using these cables everywhere while neglecting the suitability of single wall shrink tubes may be overkill because of cost factors.

Most single-wall heat shrink tubes are made of polyolefin; this cross-linked material has a shrink temperature of 100°C and can withstand temperatures up to 125°C-135°C. The most common shrink ratio for polyolefin single wall heat shrink tubes is 2:1 but these are made available in 3:1 and 4:1 ratios also if a customer demands. Dual wall heat shrink tubes are used to get protection against the continuous presence of moisture. Dual wall heat shrink sleeves provide extra sealing to prevent chemicals, fluids, and water to erode your connections. Dual wall tubes are made of two different layers- the outer layer is of cross-linked polyolefin and the inside layer is of an adhesive that melts on being heated.

Pro-tip: When you decide to use heat shrink tubes to insulate and secure your electrical installations in the best possible way, also use other heat shrink insulation accessories to insulate poles, switchgear, busbars, etc.