Insulated Fork Terminals (“Spade” Lug Connectors) with Heat Shrink (Red/Blue/Yellow)

These heat shrink fork wire terminals are designed for secure wire attachments to stud terminals, combining the easy installation of an open-end “fork” with the durability of marine-grade insulation. The Ω-shaped (horseshoe) form of the lug allows you to attach it to a screw or stud without completely removing the securing nut – you only need to loosen it and slide the fork underneath. This is very convenient when working in cramped spaces or during frequent maintenance, as it saves time and reduces the risk of dropping nuts into the bilge.

Once the wire is firmly crimped into the fork’s barrel, the adhesive-lined heat shrink insulation is heated and shrinks tightly, sealing the connection area. You get a link that is resistant to water ingress – critical for exposed connections like negative bus bars, battery terminals, or distribution posts in the engine bay. This added protection means the electrical contact will not corrode or loosen even after long exposure to a saltwater environment.

Applications & Recommendations:

• Red fork terminals (R) – For wires 0.5–1.5 mm². The small fork size is suitable for tiny connections: for example, attaching wires to an equipment ground bus or fuse block on a small boat, where the studs are smaller (M4, M5). Similarly, in automotive setups, red forks can be used to secure wires to screw terminals of small relays or ground bolts on the chassis. They are ideal for making neat, organized connections in places like fuse boxes or instrument panels.
• Blue fork terminals (BL) – For wires 1.5–2.5 mm². This is the universal size for mid-sized terminal posts (typically M5, M6 bolts). In marine environments, blue forks are used for connecting wires to main ground bus bars (negative common) or to distribution panels on yachts around 6–10 m. For instance, the wires from the negative side of the battery to various devices can be terminated with blue forks for easy fastening onto a common grounding stud. In cars or RVs, blue forks are useful for connecting accessories (lights, inverters) to screw-in fuse holders or terminal strips. They handle moderate currents (about 15–30A) and provide a stable contact.
• Yellow fork terminals (Y) – For wires 4–6 mm². The larger forks are intended for high-power circuits and M6, M8 bolts on bigger boats and vehicles. Yellow connectors are most often used for attaching cables to battery terminals, master switches, heavy-duty breaker inputs or battery isolators. For example, the ends of cables powering a trolling motor or a windlass can be fitted with yellow forks to secure under the nuts of the corresponding disconnect or breaker. These forks withstand high currents (50+ A) and ensure a broad contact surface, minimizing heating.
• Installation Notes: Ensure you choose a fork lug with the appropriate slot width (fork opening) for the diameter of the stud you’re attaching to. Generally, red forks fit ~M4/M5, blue fit M5/M6, and yellow fit M6/M8 studs, but always check the product details. When crimping, use a tool that won’t deform the fork end – focus crimping on the cylindrical barrel. After heating and cooling, verify that the adhesive has properly sealed – you should see a thin bead of glue at the edges of the insulation.
• Best Practice: When connecting multiple wires to a common bus/stud (especially with different fork sizes), arrange them so that the smallest lugs are on top (nearest the nut) and the larger ones underneath. This ensures maximum clamping force on all connectors. Also use lock washers (split ring) if possible to prevent the nut from self-loosening – fork terminals allow quick removal, but they should also be securely tightened when in place.
• These heat shrink forks are certified for marine use and can replace standard non-insulated fork or ring lugs to improve reliability. By using them, you’ll have electrical connections that won’t be compromised even after prolonged service in harsh conditions – a perfect solution for professional captains and mechanics aiming for zero-failure electrical systems.