Black Heat Shrink Tubing 30mm–100mm | 2:1 Ratio Electrical Wire Sleeving

Measure the outer diameter of your cable or bundle before shrinking. Choose a heat shrink tube with a pre-shrink inner diameter that is typically 20–30% larger than your cable's diameter. For example, if your cable bundle measures 25mm, a 30mm tube generally provides a snug fit after shrinking at a 2:1 ratio. When in doubt, size up — a slightly larger tube is easier to slide on and still shrinks down firmly.

A 2:1 shrink ratio means the tubing will shrink to approximately half its original inner diameter when heat is applied. For example, a 50mm (≈1.97") tube will shrink down to roughly 25mm (≈0.98"), conforming tightly around the cable or connector. This ratio is standard for general-purpose electrical sleeving and suits most automotive and panel wiring applications.

This tubing generally begins to shrink at around 70–90°C (158–194°F) and fully recovers at approximately 120°C (248°F). A heat gun is the recommended tool — move it steadily along the tube to shrink evenly from one end to the other. Avoid using open flames such as lighters or torches, as these can cause uneven shrinking, scorching, or damage to the underlying cable insulation.

Yes. This tubing is typically suited for automotive wiring harness protection, marine cable management, and outdoor electrical installations. Polyolefin material generally provides resistance to moisture, UV exposure, and common automotive fluids such as oil and fuel splash. For prolonged submersion or exposure to aggressive chemicals, please contact us to confirm suitability before ordering.

The available diameters (30mm–100mm) are designed for covering large cable bundles, conduit ends, butt connectors, and multi-wire harnesses rather than individual small-gauge wires. In most cases, these sizes are used where multiple wires are grouped together or where a large terminal or connector needs to be sleeved. For individual wire insulation on smaller gauges, please contact us to confirm the best size match.

Measure the total length of cable or bundle you need to cover, then add 10–15% extra to account for trimming and overlap at termination points. We offer lengths from 1 metre (≈3.3 ft) up to 10 metres (≈32.8 ft) so you can order exactly what your project requires. For large installations, ordering a longer length in one piece is generally more efficient than joining multiple shorter sections.

This type of polyolefin heat shrink tubing is generally rated for low-voltage applications up to 600V. It is suitable for automotive 12V/24V systems, residential electrical panel wiring, and similar low-voltage environments. For high-voltage or industrial-grade requirements, please contact us to confirm the appropriate specification before purchasing.