4 Pole MCBs for Three-Phase + Neutral Circuit Protection
4 pole MCBs provide simultaneous overcurrent and short-circuit protection across all three live phases and the neutral conductor. They are used on distribution circuits, plant equipment, large machinery feeds and systems where neutral disconnection is required for safety and compliance.
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These devices ensure that L1, L2, L3 and N all disconnect together during a fault, preventing dangerous phase imbalance, neutral back-feed or incomplete isolation. This makes 4 pole MCBs essential for sub-mains, industrial distribution panels, changeover arrangements and any installation with critical neutral-related safety considerations.
- Simultaneous disconnection of all three phases + neutral
- B and C curve options for different load and inrush conditions
- Ideal for three-phase distribution boards with neutral isolation
- High breaking capacities for commercial and industrial fault levels
- DIN-rail mounting for simple integration into multi-module systems
4 pole MCBs are widely used in large commercial buildings, plant rooms, workshops, industrial machinery circuits, and anywhere neutral disconnection is required for safety, maintenance or equipment protection.
63A 4 Pole 10kA MCB B Curve – WKC463B
£14.16
The WKC463B is a 63A 4 pole 10kA Miniature Circuit Breaker (MCB) designed for three-phase + neutral protection. With its B Curve trip characteristic, it is best suited to resistive load applications such as large socket outlet groups, small power distribution panels, and lighting circuits...
50A 4 Pole 10kA MCB D Curve – WKC450D
£14.16
The WKC450D is a 50A 4 pole 10kA Miniature Circuit Breaker (MCB) engineered for three-phase + neutral protection. Its D Curve trip profile is designed for very high inrush loads such as welders, heavy-duty motors, compressors, transformers, and industrial machinery. Typical use includes industrial distribution...
50A 4 Pole 10kA MCB C Curve – WKC450C
£14.16
The WKC450C is a 50A 4 pole 10kA Miniature Circuit Breaker (MCB) designed for three-phase + neutral protection. With its C Curve trip profile, it is best for inductive loads such as motors, pumps, HVAC systems, and EV charging boards in commercial distribution panels, EV...
50A 4 Pole 10kA MCB B Curve – WKC450B
£14.16
The WKC450B is a 50A 4 pole 10kA Miniature Circuit Breaker (MCB) designed for three-phase + neutral systems. With a B Curve trip characteristic, it is intended for resistive load applications such as socket outlet groups, small power distribution boards, and general lighting circuits in...
40A 4 Pole 10kA MCB D Curve – WKC440D
£14.16
The WKC 4 Pole 10kA Miniature Circuit Breaker (MCB) range provides robust protection for three-phase + neutral circuits in commercial, industrial, EV, and solar installations. With ratings from 6A to 63A and B, C, or D curve options, these breakers are built to handle overloads...
What Is a 4 Pole MCB?
A 4 pole MCB is a miniature circuit breaker that simultaneously disconnects L1, L2, L3 and the neutral conductor when a fault occurs. This ensures full isolation of the entire supply, eliminating neutral-related risks and ensuring safe maintenance and operation.
Where 4 Pole MCBs Are Used
- Three-phase distribution circuits requiring neutral isolation
- Industrial machinery with balanced or unbalanced three-phase loads
- Pumps, compressors and HVAC systems with sensitive equipment
- Sub-mains to secondary boards in factories and commercial buildings
- Switchgear, control panels and plant equipment containing mixed-phase electronics
B Curve vs C Curve 4 Pole MCBs
B Curve: Trips at 3–5 × rated current. Suitable for steady loads with low inrush.
C Curve: Trips at 5–10 × rated current. Preferred for motors, drives and equipment with higher startup demand.
Why Use a 4 Pole Device?
Standard 3 pole breakers disconnect only the three live conductors. A 4 pole MCB adds neutral disconnection, which is vital when:
- Neutral integrity is critical (TT or mixed systems)
- The load contains electronics that can be damaged by partial isolation
- Preventing back-feed from downstream circuits is essential
- Safe maintenance requires full, guaranteed isolation
Compliance & Standards
All 4 Pole MCBs in this category comply with BS EN 60898 and meet the requirements of the 18th Edition Wiring Regulations for multi-phase protection and overcurrent coordination.
Installer Benefits
4 Pole MCBs offer safe, reliable and predictable protection for complex three-phase systems. Their combined phase-neutral isolation helps prevent equipment damage, supports safer maintenance procedures and ensures compliance on circuits where neutral switching is mandatory.