The tools.
Heat Gun (1500W)
Variable heat, around 1500W. Avoid open-flame lighters. Settings by tube size: heat gun settings calculator.
Calipers / Tape
Measure bundle OD. The right tubing is two sizes — one expanded (slides on), one recovered (seals tight).
Clean Cut Tool
Razor or sharp shears. Square cut on the end means even recovery. Frayed end means uneven shrink and a weak seal.
Heat-Safe Surface
Workbench mat or scrap board. Heat gun + plastic countertop = problem. Bench protection saves the install (and the bench).
Pick the
ratio.
The standard.
- →Single-wall polyolefin
- →Insulation & mechanical protection
- →Auto loom · indoor wiring · electronics
- →Available in 13 sizes · black
Heavy duty.
- →Dual-wall, adhesive lined
- →Waterproof seal · chemical resistant
- →Marine · solar · OEM splice
- →Available in 13 sizes
Pick the
size.
The rule: tubing's expanded ID must clear your bundle. Its recovered ID must be smaller than the bundle so it grips. Aim for 20–30% shrink for a clean seal — not 100%.
- 01.Measure bundle outer diameter (OD).
- 02.Choose tubing with expanded ID ≥ bundle OD + 20%.
- 03.Confirm recovered ID ≤ bundle OD − 10%.
- 04.Add 3× joint length for tubing length.
Rule: expanded ID ≥ bundle × 1.1 · recovered ID = expanded ÷ 3
Four
steps.
Cut & slide.
Cut tubing 3× the joint length. Slide it well past the splice — onto an insulated section. You'll move it back once the wires are joined.
Join & center.
Make the electrical joint — solder, crimp, twist-cap, whatever the spec calls for. Then slide the tubing back so the joint sits centered. 25% overhang on either side.
Heat & sweep.
1500W heat gun. 6 inches off. Start at the center and sweep outward in both directions. Shrinking starts at 100°C; on dual wall keep going until adhesive shows at both ends (the liner flows at 120°C). About 8 seconds at full power.
Cool & check.
Let the joint cool 30 seconds untouched. With 3:1, you'll see a tiny bead of adhesive at each end — that's the hermetic seal. With 2:1, recovery is smooth, no wrinkles, full grip.
Six
mistakes.
× Open flame.
A lighter or torch chars the outer before the inner recovers. Always use a heat gun.
× Wrong size up.
Too-big tubing leaves a gap. Too-small won't slide on. Measure twice, order once.
× 2:1 below the waterline.
Single-wall is water-resistant, not waterproof. Use 3:1 adhesive for any wet joint.
× Dwelling on one spot.
Burns the outer, leaves the inner cold. Sweep — don't dwell.
× Shrinking onto a hot splice.
Let the solder joint cool first. Adhesive seal degrades if the joint is > 150°C.
× Moving while cooling.
Shape sets as it cools. Bend during cooldown and the seal cracks. 30 seconds, untouched.