1-1/4 inch heat shrink tubing is sized for large multi-wire bundles, grouped cable assemblies, and industrial cable entry sealing where a standard single-conductor size is not applicable. Typical applications include motor control center cable exits, large wire bundle entries at panel knockouts, and marine cable transits where multiple conductors are sealed as a group. At 31mm expanded diameter, this tube accommodates substantial conductor bundles and recovers to approximately 10.3mm after full heat application. The 3:1 adhesive-lined construction is essential for bundled applications — the irregular cross-section of mixed-size cables packed together leaves voids around a non-adhesive sleeve, but the adhesive liner flows into those voids and creates a complete environmental seal blocking moisture and dust at the penetration point. For indoor dry-area cable management where waterproofing is not required, the 2:1 standard is a lower-cost option in this size. The 1-1/4" size is widely used in industrial motor control wiring, large panel cable entry sealing, and marine cable transits where multiple conductors must be sealed as a single assembly.
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SKU: B0D646QZCP · 1-1/4" (31mm) · 20 ft
Complete dual-wall adhesive performance in a bulk roll format. Permanently waterproof, 600V rated, and rated for the harshest environments.
Sizing over a connector? The Wire Gauge row above is for bare conductor. Heat shrink must be sized to the widest point it passes over, so a crimped butt splice or lug barrel needs a larger tube than the wire alone — a 22–18 AWG splice barrel measures 5–6mm, a 16–14 AWG barrel 7–8mm, and a 12–10 AWG barrel 9–11mm. Measure the barrel, allow about 20% clearance, and confirm the recovered diameter is smaller than the narrowest thing the tube must grip. Use the size calculator.
High quality and amazing value for the price
I'll never buy individual bags of heat shrink tubing again. This is very high quality with a shrink ratio that is truly amazing (all of the tubing from this company is). I wonder if I'll be able to use this entire roll in 10 years!
Good quality and sealing heat shrink
Heat shrink works good. Bought this for work. Makes a nice sealed wire connection. Good quality, better than pre cut heat shrink, you can make whatever length you want.
I LIKE THIS!
I solder, and heat shrink, all of my automotive electrical connections. This is a great product, and I can cut it to any length. The price is great, and the shipping was fast!
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1-1/4 inch (31mm) takes large multi-wire bundles and industrial cable assemblies up to roughly 25mm across, recovering to about 10.3mm. Most of its work happens at penetrations — bulkheads, gland plates, conduit entries — where the job description changes. The tube is no longer insulating a conductor; it is forming the transition between a cable and a hole in a barrier meant to keep water on one side of it.
A working penetration seal bonds to the cable jacket on the wet side, to itself around the full circumference, and to whatever fitting or gland carries the load. Miss any one and the assembly leaks, usually slowly enough that the first sign is corrosion inside the enclosure rather than water on the floor.
The jacket surface is the one most often got wrong. Hot-melt adhesive bonds well to clean polyolefin and PVC and poorly to anything carrying silicone, oil or release agent. Wipe the jacket with isopropyl alcohol and let it flash off before the tube goes on. That costs a minute and is the difference between an adhesive bond and adhesive merely sitting in contact.
Length matters as much as diameter. Overlap at least 25mm of continuous jacket on the wet side so the bond has real area to develop, rather than trimming the tube neatly to the fitting. At 31mm the wall carries enough adhesive to fill a substantial gap, but only over the length it actually covers.
| Property | Figure | Why it matters |
|---|---|---|
| Expanded diameter | 31mm (1-1/4") | Clears bundles and assemblies up to about 25mm |
| Recovered diameter | ≈10.3mm | Follows the step from a gland down to a cable jacket |
| Overlap to allow | ≥25mm of clean jacket | Adhesive needs bond area, not just contact |
| Surface prep | Isopropyl alcohol, flashed off | Hot-melt bonds poorly through oil or release agent |
| Wall type | 3:1 dual wall, hot-melt lined | Seals bulkhead and conduit entries against ingress |
| Roll length | 20 ft | Four to six large terminations, or two to three penetrations |
Large diameters need longer, gentler heating. The outer wall reaches recovery temperature well before the liner flows through the full thickness.
Step to 1-1/2 inch, which clears roughly 30mm. Clearance is not optional at this scale — a tube that has to be worked on will not seat evenly.
The 1-1/4" 2:1 on a 60ft roll does mechanical protection and labelling in dry cable trays and MCC panels at a lower cost per foot.
A 20ft roll is a stocking decision. For a single penetration, the 10ft short pack of the same tubing is the sensible way to confirm the fit first.
A rated bulkhead penetration needs a listed transit or firestop system. Heat shrink seals against water; it is not a substitute for a rated barrier assembly.
Keep reading →1-1/2" 3:1 Dual Wall — the next size up · 1-1/4" 3:1 Dual Wall — 10ft short pack · Adhesive Lined Heat Shrink Tubing
Verify the expanded diameter is 20–30% larger than your wire or connector. The tubing must slide freely before heat is applied — if it drags, go one size up.
Cut to length and thread onto the wire or cable before making the splice or crimp. Overlap each terminal or connector end by at least 10mm for a proper seal.
The tubing starts shrinking at 100°C, but the adhesive liner only flows at 120°C — so keep the heat gun moving past the point where it looks shrunk. Start at the center and work outward to push air toward the ends. Adhesive will appear at the tube ends — that is your visual seal indicator.
The tubing should be tight and uniform with adhesive visible at both ends. No gaps, lifting, or cold spots. Pull-test the finished connection to confirm the adhesive bond.
Actual 1-1/4" tube at full expanded diameter (31mm) and after heat recovery. Use this as your fit reference before cutting.
Seals the entry point of cable bundles through bulkheads, firewalls, and conduit fittings against moisture, dust, and vapors.
Provides insulation and end sealing on large industrial conductors in switchgear, motor control centers, and distribution equipment.
Seals conduit ends and cable transition points in outdoor electrical installations against water ingress and UV degradation.
Band-marks and mechanically protects large pipe, hose, and cable assemblies in process plants, mining, and heavy industry.
Provides a degree of flame barrier at bulkhead and firewall penetrations for large cable bundles in industrial and marine applications.
Applied at panel entry and exit points to distribute bending stress and prevent jacket damage on large-diameter industrial cables.
Recovered diameter is approx. 1/3 of the expanded size shown · All sizes ship to USA & Canada
