WSB1-63 Series 4P Miniature Circuit Breaker 6kA/10kA 6–63A

A 4P MCB switches and protects all four conductors of a three-phase supply plus neutral (L1, L2, L3, N) in a single device. It is used in three-phase distribution boards, commercial buildings, small factories, and any installation where the neutral must be isolated together with the phases for safety or maintenance. Because all poles move together, it guarantees a complete break on a three-phase circuit.

It uses a thermal-magnetic operating mechanism. The thermal part is a bimetallic strip that heats up and bends under sustained overcurrent, tripping after a delay (inverse-time) to protect cables from overload. The magnetic part is a solenoid that fires instantaneously when fault current reaches the trip band of the curve (B, C or D), clearing a short circuit within milliseconds.

Breaking capacity (Icn under IEC 60898-1) is the maximum prospective short-circuit current the MCB can safely interrupt. A 6kA version can clear up to 6,000 A, while the 10kA version clears up to 10,000 A without being damaged. Choose 6kA for typical residential and light-commercial boards where the upstream transformer limits fault level, and 10kA for panels close to a transformer or in high-fault industrial installations.

The series is offered in B, C and D characteristics. Curve B trips magnetically at 3–5× In and suits purely resistive loads such as lighting. Curve C trips at 5–10× In and is the general-purpose choice for sockets, small motors and fluorescent lighting. Curve D trips at 10–20× In and is reserved for high-inrush loads such as large motors, transformers and welding equipment.

Standard ratings include 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A and 63A. Pick the rating so that In is at least the circuit design current (Ib) but no greater than the current-carrying capacity of the cable (Iz) after derating for ambient temperature and grouping. A common rule of thumb is to keep continuous loads below 80% of In, and for motor circuits size In at least 125% of the full-load current.

Yes. The WSB1-63 4P is rated for AC 50/60 Hz at 230V/400V between phases and neutral, which matches standard three-phase commercial and industrial distribution. It is not suitable for DC circuits or voltages above its rated working voltage; confirm the marking on the front of the device before installation.

It snaps onto a standard 35 mm DIN rail inside a distribution board. Connect the supply (incoming L1, L2, L3 and N) to the top terminals and the load to the bottom terminals, tightening each terminal to the torque stated in the datasheet. Route conductors neatly, leave the correct bare-wire length, and verify phasing and neutral continuity before energising.

If it trips after running for several minutes, suspect an overload (too many appliances on the circuit) or high ambient temperature inside the board. If it trips instantly when a motor or large load starts, the magnetic trip band is being hit — a C or D curve may be needed instead of B. If it trips immediately even with loads disconnected, there is likely a short circuit or earth fault in the wiring; stop resetting and have an electrician test the circuit.

The series is designed and type-tested to IEC 60898-1, the international standard for miniature circuit breakers for household and similar low-voltage installations, and carries CE marking showing conformity with applicable EU directives. Always confirm the specific certificate number shown on the product label or datasheet for the exact model and rating being purchased.

It is commonly used as the main or sub-main protective device in three-phase distribution boards for offices, retail units, small factories, hotels and residential complexes with three-phase supply. It protects three-phase sockets, pumps, air-conditioning units, machine tools and branch feeders, while also isolating all live conductors including neutral during maintenance.