WNB1-63 4P MCB 6kA Four Pole Circuit Breaker

A 4-pole MCB protects and switches all four conductors of a three-phase-and-neutral circuit — L1, L2, L3, and N — together on one handle. Use it where you want to protect and isolate a three-phase load that also needs the neutral switched, such as a three-phase distribution branch, a panel incomer, or equipment requiring all poles isolated on trip.

The 6 kA rating is the rated short-circuit breaking capacity: the maximum prospective fault current (6000 A) the breaker can safely interrupt and clear. Because three-phase panels near transformers can see high fault levels, the 6 kA rating makes this MCB suitable for modern commercial/industrial boards; it must still be ≥ the calculated available fault current at its location.

It uses the same thermal-magnetic principle as other MCBs: a bimetallic strip heats and bends to give a delayed trip on sustained overload, while a solenoid plunger releases instantly on a short circuit. The four poles are mechanically linked so that a fault on any pole opens all of them together, and the arc is quenched in internal arc chutes.

Like other MCBs, WNB1-63 units are typically offered in B, C, or D curves determining the instantaneous trip range. Type C is the most common for general three-phase and motor-circuit duty, B for low-inrush resistive loads, and D for high-inrush loads such as transformers or large motor starts — confirm the exact curves and ratings offered on the datasheet.

A 4P breaker switches and links the neutral with the three phases in one device, so all four poles open together. A 3P breaker protects only the phases, leaving the neutral on a separate terminal bar. Choose 4P when you require the neutral to be switched or isolated together with the phases, per local wiring rules.

Calculate the full-load current of the three-phase load, size the conductors to carry it, and select an MCB rating (In) above the design current but not exceeding the cable's ampacity. Account for the load type in choosing the B/C/D curve so motor or transformer inrush does not cause nuisance trips.

Clip the breaker onto a standard 35 mm DIN rail in the distribution board, then connect L1/L2/L3 and the neutral to the correspondingly marked line terminals and the load-side conductors to the load terminals. Observe the marked line/load orientation, tighten terminals to datasheet torque, and keep the supply isolated during wiring.

A 4-pole MCB of this type is normally rated for three-phase AC (commonly 400 V between phases, per IEC 60898-1). Confirm the exact rated voltage and the number of protected poles on the nameplate, because voltage and pole ratings must match the supply being protected.

Look first for an overload (load current above the rating on one or more phases), a phase-to-phase or phase-to-neutral short circuit, or a failed connected three-phase appliance. Balance the phases, isolate loads one at a time, and inspect wiring and terminals for damage — repeated resetting without finding the cause is unsafe.

The WNB1-63 4P MCB is a low-voltage miniature circuit breaker covered by IEC 60898-1 and commonly marked CE for the EEA market. Always check the datasheet for the exact rated current, breaking capacity, and curve markings that define its actual duty.