4 Pole MCBs for Three Phase & Neutral Protection
4 pole MCBs are used where a circuit requires overcurrent protection across three phases plus neutral. They are commonly specified on three-phase distribution systems, sub-mains, plant equipment, and other installations where a standard 3 pole device may not provide the required switching arrangement.
These devices are typically chosen for commercial and industrial applications where full phase and neutral disconnection is part of the protection or isolation strategy.
Quick answer: A 4 pole MCB protects a three-phase circuit with neutral, switching all three live conductors and the neutral together. They are commonly used where a circuit design calls for phase and neutral disconnection in one device.
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Compared with a standard 3 pole MCB, a 4 pole device adds neutral switching, which can be important on certain distribution circuits, plant setups, and mixed-load systems. This makes them a practical choice where the installation design requires a combined phase-and-neutral protective device rather than live pole switching alone.
- Three phase + neutral switching – for circuits requiring 4 pole protection
- B and C curve options – to suit different load and inrush characteristics
- Suitable for distribution boards and sub-mains – in commercial and industrial environments
- Used on plant and equipment circuits – where a 4 pole arrangement is preferred
- DIN-rail format – for integration into multi-module boards and panels
Need related three-phase protection products? Browse our 3 pole MCBs, three phase range, and three phase boards & accessories. For delivery and returns, see our delivery information and returns policy.
20A 4 Pole 10kA MCB C Curve – WKC420C
£15.05
The WKC420C is a 20A 4 pole 10kA Miniature Circuit Breaker (MCB) designed for three-phase + neutral systems. With its C Curve trip characteristic, it is suited to inductive load circuits such as motors, HVAC, pumps, and EV charging sub-circuits in commercial boards, EV distribution...
20A 4 Pole 10kA MCB B Curve – WKC420B
£14.16
The WKC420B is a 20A 4 pole 10kA Miniature Circuit Breaker (MCB) designed for three-phase + neutral protection. With its B Curve trip characteristic, it is best suited for resistive loads such as small power circuits, lighting systems, and distribution boards in three-phase networks, EV...
16A 4 Pole 10kA MCB C Curve – WKC416C
£15.05
The WKC416C is a 16A 4 pole 10kA Miniature Circuit Breaker (MCB) designed for three-phase + neutral protection. With its C Curve trip characteristic, it is suitable for inductive load circuits including motors, HVAC, and EV charger distribution boards in commercial three-phase systems, EV installations,...
16A 4 Pole 10kA MCB B Curve – WKC416B
£15.05
The WKC416B is a 16A 4 pole 10kA Miniature Circuit Breaker (MCB) designed to protect three-phase + neutral circuits. With its B Curve trip profile, this breaker is suited for resistive load circuits such as general lighting, small appliance, and socket outlets in commercial boards,...
What Is a 4 Pole MCB?
A 4 pole MCB is a miniature circuit breaker designed for three-phase circuits with a neutral conductor. It switches L1, L2, L3 and neutral together, making it suitable for installations where a 4 pole protective device is required as part of the circuit design.
When 4 Pole MCBs Are Used
- Three-phase distribution circuits with neutral present
- Sub-mains feeding secondary boards in commercial and industrial settings
- Plant and machinery circuits where the switching arrangement includes neutral
- Control panels and mixed-load systems where a 4 pole device is preferred
- Installations requiring a combined phase and neutral protective format
4 Pole vs 3 Pole MCBs
The key difference is that a 3 pole MCB switches the three live conductors only, while a 4 pole MCB adds neutral switching as well. Whether a 3 pole or 4 pole device is the right choice depends on the installation design, the system arrangement, and the requirements of the circuit being protected.
B Curve vs C Curve 4 Pole MCBs
B curve 4 pole MCBs are generally used where the circuit has lower inrush current and a more predictable load profile. C curve 4 pole MCBs are more suited to applications where equipment may draw a higher start-up current, such as motors, compressors, or other inductive loads.
- B curve – for lower inrush and more standard load conditions
- C curve – for circuits with higher start-up current or inductive equipment
Typical Applications
- Commercial distribution boards – where three phase and neutral protection is needed
- Industrial equipment – including plant circuits and mixed-load machinery supplies
- HVAC and pump systems – depending on the switching and load characteristics
- Workshop and facility power systems – where sub-main and board protection is being specified
Used Alongside Three Phase Boards & Protection
4 pole MCBs are commonly specified alongside three phase boards and protection, three phase boards & accessories, 125A TPN boards with SPD, and wider MCB ranges depending on the installation layout.
FAQs on 4 Pole MCBs
What is a 4 pole MCB used for?
A 4 pole MCB is used on three-phase circuits with neutral where the protection and switching arrangement requires all three phases and the neutral to be handled within one device.
What’s the difference between a 3 pole and 4 pole MCB?
A 3 pole MCB switches the three live conductors only. A 4 pole MCB also includes neutral switching.
When should I choose B curve or C curve?
B curve is generally used for lower inrush circuits, while C curve is chosen where the load has a higher start-up current. The correct choice depends on the circuit design and connected equipment.
Are 4 pole MCBs only for industrial installs?
They are most commonly used in commercial and industrial environments, but the right choice always depends on the design of the specific three-phase circuit.
Why Buy 4 Pole MCBs from Power & Data UK?
Power & Data UK supplies trade-focused circuit protection products with dependable UK stock, practical product choice, and fast dispatch. Orders over £30 qualify for free UK mainland next-day delivery, and products are backed by a 2-year manufacturer warranty. For unwanted items, see our returns policy.