High Current MCBs (63A–125A) for Heavy-Load Circuits
High current MCBs from 63A to 125A are designed for circuits carrying significant load, such as sub-mains, large machinery, commercial distribution boards and high-demand equipment feeds. They deliver reliable overcurrent and short-circuit protection where standard ratings are not sufficient.
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These breakers are built to handle higher continuous currents and elevated fault levels, making them suitable for main outgoing ways, panel board circuits and heavy plant supplies. Available in single, double, three and four-pole versions, they allow installers to protect everything from large single-phase loads to full three-phase plus neutral sub-feeds.
- 63A–125A ratings for high-load circuits and sub-mains
- Multiple pole configurations for single and three-phase systems
- B and C curve options to match load and inrush characteristics
- High breaking capacities suitable for commercial and industrial fault levels
- DIN-rail compatible for use in panel boards and distribution boards
High current MCBs are commonly specified in commercial, industrial and larger domestic installations where main feeders, plant equipment and group circuits need robust, predictable protection.
1 Pole 10kA MCB 63A B Curve WKC163B
£5.00
The WCED WKC Series 10kA Miniature Circuit Breakers (MCBs) are high-performance devices designed for precise overcurrent detection and short-circuit protection. Built to handle demanding applications, they provide reliable protection for domestic, commercial, and industrial distribution systems – including solar PV with SPD and EV charging...
Where High Current MCBs Are Used
63A–125A MCBs are chosen for circuits that draw more current than standard final circuits, or where a distribution board way is feeding multiple downstream loads.
Typical Applications
- Sub-mains supplying secondary consumer units or distribution boards
- Large motors, pumps and compressors
- Commercial kitchens and high-demand catering equipment
- Industrial machinery and process equipment feeds
- Heating, HVAC and plant circuits with sustained high loads
B Curve vs C Curve in High Current Ratings
B Curve: Trips at 3–5 × rated current, suited to steady high-load circuits with low inrush.
C Curve: Trips at 5–10 × rated current, ideal for motor-driven or surge-heavy loads where startup currents are significantly higher than running currents.
Single, 2, 3 and 4 Pole Options
High current MCBs are available in different pole configurations to suit the supply and isolation requirements:
- Single-pole for heavy single-phase loads
- 2 pole where line and neutral disconnection is required
- 3 pole for three-phase loads without neutral switching
- 4 pole for three-phase + neutral circuits needing full isolation
When to Specify 63A–125A Protection
These ratings are used when calculated load current, cable capacity and design current exceed what a standard 32A or 40A device can safely handle. They are also common at the top end of distribution boards feeding banks of circuits or large items of plant.
Compliance & Standards
All High Current MCBs in this category are designed to comply with BS EN 60898 or equivalent performance standards, and support full compliance with 18th Edition Wiring Regulations when properly coordinated with fault levels and cable sizing.
Installer Benefits
High current MCBs provide robust, dependable protection for heavier circuits while maintaining the familiar DIN-rail format used across modern boards. They allow electricians to design and maintain large-load systems with confidence in both overload and short-circuit performance.