Black Heat Shrink Tubing 10mm–80mm | 2:1 Ratio Electrical Wire Sleeving

Generally, select a tubing diameter that is 20–30% larger than the outer diameter of the cable or connector you need to cover. For example, for an 8mm cable, a 10mm (3/8") tube is typically a good fit. After shrinking at a 2:1 ratio, the tubing will conform tightly around the substrate. When in doubt, size up — tubing that is slightly oversized before shrinking is easier to work with than tubing that is too tight to slide over the cable end.

A 2:1 shrink ratio means the tubing will shrink to approximately half its original inner diameter when heat is applied. For example, a 20mm (3/4") tube will shrink down to roughly 10mm (3/8"), creating a snug, protective sleeve around your wire or cable. The length of the tubing also shortens slightly during the process — typically by around 5–10% — so cut your pieces a little longer than the area you need to cover.

This tubing is generally suitable for outdoor use in dry to moderately humid environments. Polyolefin heat shrink provides resistance to moisture, UV exposure, and abrasion, making it a common choice for outdoor electrical cable sleeving and marine wiring runs. For fully submerged applications or extreme saltwater exposure, we recommend confirming suitability with our team before ordering.

Heat shrink tubing of this type typically begins to activate at around 70–90°C (158–194°F) and fully shrinks at approximately 120°C (248°F). A heat gun is the recommended tool — move it steadily along the tubing to ensure even shrinkage. Avoid using open flames such as lighters or torches, as they can scorch, bubble, or unevenly shrink the tubing, compromising the seal.

Yes. This black heat shrink sleeving is commonly used in automotive wiring harnesses, car audio cable management, and under-hood electrical repairs. The black finish blends with most factory wiring, and the tubing is generally resistant to engine-bay temperatures and minor fluid exposure. For high-heat zones directly adjacent to exhaust components, a higher-rated tubing may be more appropriate — contact us to confirm.

For small repair jobs or single-project use, a 25-metre (≈82 ft) roll is typically sufficient. For workshop stock or recurring electrical projects, the 50-metre (≈164 ft) or 100-metre (≈328 ft) rolls offer better value per metre. Note that larger diameter sizes (28mm–80mm) are available in 25-metre rolls, while smaller diameters (10mm–25mm) are available in all three lengths.

Wall thickness after shrinking varies by diameter. For standard 2:1 polyolefin heat shrink tubing, the recovered wall thickness is generally in the range of 0.6mm–1.5mm depending on the size selected. Contact us to confirm the exact wall thickness for your specific diameter before ordering if this is a critical specification for your application.