5/16 inch heat shrink tubing fits 8–10 AWG wire — the gauge used for high-current automotive battery feeds, alternator output cables, winch solenoid leads, LiFePO4 battery connection terminals, and solar charge controller output wiring. ABYC E-11 Table XI rates 10 AWG at 30A and 8 AWG at 40A in a standard bundled marine installation; at these current levels, connection integrity at each terminal crimp is critical to both system performance and thermal safety. At 8mm expanded diameter, this tube slides freely over 8 and 10 AWG conductors and recovers to approximately 2.7mm after full heat application. The 3:1 adhesive liner mechanically locks the sleeve to the lug or connector body while simultaneously providing the waterproof seal — a dual benefit that 2:1 non-adhesive tubing cannot replicate. For indoor electrical panel wiring in a dry environment where the connection is not subject to moisture or vibration, the 2:1 standard is a lower-cost option in this size. The 5/16" size is the standard for LiFePO4 battery bank connection terminals, battery tender leads, and solar charge controller output wiring on boats and RVs.
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SKU: B0D63SF37M · 5/16" (8mm) · 60 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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5/16 inch (8mm) is sized for bare 8–10 AWG — winch feeds, solar charge-controller output, LiFePO4 interconnects and high-current accessory runs. ABYC E-11 Table XI rates 10 AWG at 30A and 8 AWG at 40A bundled. Its more common job, though, is covering the ring terminals and small lug barrels used on 10 AWG, which measure 7–8mm across. That is the number that decides the size.
A ring terminal has one opening that matters: the throat where the conductor enters the barrel. Everything else on the terminal is solid metal. Water reaching that throat runs straight onto bare copper under the crimp, and from there it wicks back into the cable under the jacket where it cannot be seen or dried.
At 30 to 40 amps the consequence is thermal rather than electrical. A corroded crimp does not open — it develops resistance, and resistance at 40 amps produces heat measured in watts at a single point. The terminal discolours, the crimp anneals slightly, contact pressure drops, and the cycle repeats. Installers usually find it as a hot lug on a thermal check rather than as a dead circuit.
The adhesive liner is aimed exactly at that throat. It flows at 120°C, fills the annular gap between the barrel mouth and the cable jacket, and bonds to both. Slide the tube on so it overlaps the barrel by at least 10mm and covers the same length of jacket behind it, then heat from the terminal end toward the cable so trapped air escapes ahead of the shrink front.
| Property | Figure | Why it matters |
|---|---|---|
| Expanded diameter | 8mm (5/16") | Clears the 7–8mm ring terminal barrels used on 10 AWG |
| Recovered diameter | ≈2.7mm | Grips bare 8–10 AWG and the jacket behind a terminal |
| Bare wire range | 8–10 AWG | 30A for 10 AWG, 40A for 8 AWG bundled (ABYC E-11 Table XI) |
| Clearance to allow | ≈20% on the widest point | A tube that drags cold traps air and recovers with a void |
| Wall type | 3:1 dual wall, hot-melt lined | Fills the barrel throat, which is the only way in |
| Roll length | 60 ft | Multiple systems — this size is used a few terminations at a time |
On a terminal, measure across the barrel at its widest, including any inspection window. The wire gauge is not the sizing input here.
Step up to 3/8 inch rather than forcing it. Forcing stretches the tube before heat is applied, and a pre-stretched tube recovers unevenly and leaves a void at the shoulder.
Lug palms on 8 AWG and up are far wider than the barrel. Measure the palm; that usually puts you at 1/2 inch or 5/8 inch, not 5/16 inch.
With no moisture to exclude, the 5/16" 2:1 covers and insulates at lower cost. Spend the adhesive where weather actually reaches.
Our 600V rating is in volts rms, not DC. On a 1000 Vdc PV system the conductor carries the rating (UL 4703, RHW-2/USE-2) and this tubing seals the termination.
Keep reading →Heat Shrink for Solar PV Wiring · Heat Shrink for Battery Terminals · 5/16" 3:1 Dual Wall — 10ft short pack
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 5/16" tube at full expanded diameter (8mm) and after heat recovery. Use this as your fit reference before cutting.
Seals bilge pump leads, navigation light splices, and sonar cable entries against continuous moisture and saltwater exposure.
Protects harness connectors, oxygen sensor leads, and battery tender connections in high-temperature, high-humidity engine compartments.
Seals outdoor junction connections, landscape lighting harness splices, and irrigation system wiring from water ingress.
Seals battery tender leads, solar charge controller wiring, and inverter connections against corrosion and moisture.
Used on fresh water pump wiring, slide-out harnesses, and underbody electrical runs on recreational vehicles.
Seals cable entries and harness connections in outdoor and washdown-rated control enclosures where IP protection is required.
Recovered diameter is approx. 1/3 of the expanded size shown · All sizes ship to USA & Canada
