Straight Wire Splice Connectors (Heat Shrink Butt Connectors) – Red/Blue/Yellow

These straight heat-shrink wire splices (“butt connectors”) provide a quick and effective way to join two conductors into one continuous line while maintaining electrical safety and environmental resistance. The body of each splice is made from highly conductive copper, tin-plated for corrosion protection. The outer sleeve is a special heat-shrink tube with an inner adhesive layer: when heated, the tube contracts and the adhesive melts and fills the space, bonding to the wires and connector. The result is a connection that is both electrically reliable and mechanically strong, with a fully sealed joint that prevents moisture or air ingress.

Heat shrink butt splices are especially valued in marine environments. On a boat, you often need to extend wires (e.g., adding a new pump or device) or repair broken cables (damage from chafing, corrosion, or accidental cuts). With these connectors, you can restore connectivity on the spot: all you need is a crimping tool and a source of heat (hot air gun or even a lighter in a pinch). There’s no need for soldering – which is difficult on a rocking, windy, or damp boat – instead, the splice provides a stable mechanical link and a solder-like effect via the adhesive layer.

Applications & Tips:

• Red splices (R) – For small gauge wires 0.5–1.5 mm². Used for splicing thinner wires, e.g., interior lighting leads, sensor cables, control circuits. In boats around 3–6 m, red connectors are suitable for repairing or extending wires for LED lights, small fans, USB chargers, etc., where currents are low. We recommend keeping spare red splices on board for emergency fixes of thin wiring (for instance, if a transducer or instrument line breaks).
• Blue splices (BL) – For wires 1.5–2.5 mm². This is the universal size for most standard electrical circuits in boats and vehicles. Blue splices can join a two-core cable for a bilge pump, extend the wiring to a navigation light, or mend a cut wire to a car’s cigarette lighter. They handle moderate currents (up to ~20–25A) and are the backbone of service kits for medium-sized boats (5–9 m). When installing additional equipment – for example, a new spotlight on the bow – blue connectors will allow you to safely insert the extension cable.
• Yellow splices (Y) – For thicker conductors 4–6 mm². Intended for high-load connections and larger vessels (10+ m). Yellow connectors are ideal when working with power cables: for example, extending the main +12V feed from a battery to new equipment, connecting sections of wiring for solar panels, or repairing a damaged windlass cable. They can handle 40+ A currents and, once shrunk, become extremely robust – the wire will likely break before the connection fails. Yellow splices are essential in the toolkit of yacht and RV electricians where heavy currents flow.
• Usage Instructions: Select the correct size for your wire gauge. Strip about 6-8 mm of insulation from each of the two wires to be joined. Insert the stripped ends into each side of the butt connector until they nearly meet in the middle. Use a crimp tool to compress the metal barrel – crimp one side first, then the other (some tools allow doing both at once). Check that the wires are firmly held – a slight tug should not pull them out. Then heat the shrink tubing evenly until it turns transparent enough to show the outline of the internal barrel and a bit of adhesive seeps out at the ends. Your connection is now sealed.
• Preventive Measures: The finished splice can be further protected mechanically by securing it with zip ties or clamps to a nearby solid support – this relieves any constant tension on the joint. This is especially important for wires that are run taut or subject to motion (such as those around an engine or steering system). By anchoring the cable, you reduce the strain on the splice itself, ensuring longevity of the repair.
• Once installed and cooled, a properly made butt splice is maintenance-free and should last as long as the original wiring. It’s a permanent-grade repair that meets or exceeds OEM standards for marine and automotive use, giving you confidence in the integrity of your electrical system. Keeping a range of these heat shrink splices in your onboard or garage toolkit means you can tackle any wiring emergency or upgrade with professional-quality results.