We now offer the Staubli MC4 crimping tool which includes BOTH die sets, eliminating the need to purchase separate die sets and take the guess work out of knowing what to order.
Stäubli MC4 B-crimp (stamped and formed or butterfly) and O-crimp (barrel) connectors represent two different styles of electrical contact designs used to connect photovoltaic (PV) cables to MC4 connector housings.
The B-crimp is the modern standard used for Stäubli's official MC4 and MC4-Evo 2 product lines, designed for secure, open-barrel crimping, while O-crimp refers to a closed-barrel or circular crimp style, often found in different or older contact designs.
At a Glance: B-Crimp vs. O-Crimp
| Feature | B-Crimp (Open Barrel) | O-Crimp (Closed Barrel) |
|---|---|---|
| Shape | U-shaped wings that fold over (B-shape) | Circular/Tubular barrel |
| Stäubli Use | Standard for Original MC4/MC4-Evo 2 | Used in 8AWG & 6AWG terminals |
| Tooling | Requires dedicated B-crimp/open-crimp die | Requires specific O-crimp/round die |
| Best For | Modern, high-reliability field assembly | Some heavy-gauge (8AWG+) applications |
Stäubli MC4 B-Crimp (Open Barrel)
- Design: These contacts feature two sets of wings (flaps) that fold inward, catching the conductor strands and insulating layer securely. When crimped correctly, it creates a "B" or similar shape.
- Advantages: Stäubli’s official crimping pliers (e.g., PV-CZM series) are designed for these open B-crimp contacts, ensuring a reliable, certified connection (TÜV/UL) that is easy to inspect visually.
Stäubli O-Crimp (Closed/Barrel Crimp)
- Design: A closed, circular tube where the wire is inserted, and the die crushes the cylinder inward around the wire.
- Application: While less common in standard field assembly, closed crimps are often used for larger, 8 AWG and or 6AWG solar wires or in specific factory-crimped, high-current applications.
- Warning: Using standard B-crimp pliers on O-crimp contacts will likely lead to a poor, unsafe connection, as the dies are designed to fold, not crush.
Key Takeaways for Installers
- Tooling Mismatch: The most crucial difference is that they require different crimp dies. Stäubli warns that B-crimp tools should not be used on closed-barrel (O-crimp) contacts.
- Stäubli Quality: Stäubli insists on using their proprietary, or validated, tools to ensure the connection stands up to 20+ years of environmental stress, preventing solar system fires, which are often caused by faulty crimps.
- Visual Inspection: B-crimps allow for easy verification that all strands are caught, whereas O-crimps can hide voids inside the closed tube.