1 inch heat shrink tubing fits 300 to 400 MCM cable — used for utility service entrance wiring, large cable bundle sealing, conduit end protection, industrial panel entry, and marine cable transits through bulkheads. At this MCM size, conductors carry 260A to 335A per NFPA 70 Table 310.15 — typically the main service entrance conductors, large inverter feeds, or primary distribution feeders in commercial and industrial work. At 25.4mm expanded diameter, this tube slides freely over large-diameter cable assemblies and recovers to approximately 8.5mm after full heat application. The tube is commonly applied over multi-conductor bundles rather than a single cable at this diameter — the adhesive liner conforms to irregular bundle shapes and provides a sealed entry that a rigid fitting cannot match. For indoor dry-area conduit work where waterproofing is not required, the 2:1 standard is a lower-cost option in this size. The 1" size is the standard for sealing cable entry points at weatherproof enclosures, outdoor junction boxes, and marine bulkhead penetrations where a bundle of smaller conductors passes through a single opening.
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SKU: B0D64B2BMS · 1" (25.4mm) · 30 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 inch (25.4mm) covers 300–400 MCM conductors, large multi-wire bundles and the lug barrels used on 4/0 AWG. It recovers to roughly 8.5mm, so one diameter spans a range that would need two or three sizes of 2:1. But the reason this size is specified with an adhesive liner is geometric rather than dimensional: a bundle has valleys between its conductors, and a tube that only covers them leaves a channel running straight through the middle of the seal.
Lay three or four conductors together and the outline is a rounded triangle or square with deep grooves between the strands. A shrinking tube follows the outer envelope of that shape. It touches the high points, spans the grooves, and stops. From outside the finish is convincing; inside there are continuous air passages from one end of the tube to the other.
Those passages are the leak path. Water entering at one end of a bundle penetration travels the full length inside the tube and emerges wherever the conductors separate — commonly inside the enclosure the penetration existed to protect. A tube that covers a bundle without filling it can move water rather than stop it.
The hot-melt liner is what closes the grooves. It flows at 120°C, and the recovering wall presses it into the valleys until the cross-section is solid. This is why the dual-wall product is the correct specification for cable entries at panel knockouts, conduit terminations and outdoor enclosure penetrations, and why the single-wall version of the same diameter is correctly sold for bundling and identification instead.
| Property | Figure | Why it matters |
|---|---|---|
| Expanded diameter | 25.4mm (1") | Passes over 300–400 MCM and 4/0 lug barrels |
| Recovered diameter | ≈8.5mm | A single size spans what two or three 2:1 sizes would cover |
| Typical bundle OD | Up to ≈20mm | Measure at the fattest point, including tape or lacing |
| Wall type | 3:1 dual wall, hot-melt lined | Fills the valleys between conductors instead of bridging them |
| Ratings | UL 224 Recognized, -55°C to +125°C | Suitable for wet-location cable penetrations |
| Roll length | 30 ft | A few 6–8 in pieces per job, so this is genuine facility stock |
On a bundle, let the tube overlap solid jacket at both ends. Adhesive needs somewhere continuous to bond to, or the seal ends where the bundle opens out.
Clearance disappears quickly at this scale. Move to 1-1/4 inch, which clears roughly 25mm and still recovers to about 10.3mm.
For abrasion protection and identification in a climate-controlled room, the 1" 2:1 on a 90ft roll is the right product; there is nothing there for adhesive to exclude.
Heavy-wall cable splice tubing is a separate product class with its own qualification. Do not substitute UL 224 tubing into a splice kit specification.
Rated 600V rms. On a 1000 Vdc battery or solar run the conductor insulation carries the rating, and this tubing is a seal over it, not the insulation itself.
Keep reading →1-1/4" 3:1 Dual Wall — for larger bundles · Adhesive Lined Heat Shrink Tubing · Heat Shrink Size Calculator
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" tube at full expanded diameter (25.4mm) 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
