Manufacturer AC 50Hz/60Hz Wsb5-40 Low Voltage MCB Circuit Breaker

The WSB5-40 is Westhomes' compact low-voltage miniature circuit breaker (MCB) family built around a 40 A frame size, designed for residential and light-commercial final distribution. It is the smaller, household-oriented counterpart to higher-current WSB1-125 type breakers. The series covers the everyday protection tasks — lighting, sockets, fan and small appliance circuits — where a 40 A frame is more than enough.

In this context "low voltage" refers to the IEC definition of nominal voltages up to 1000 V AC, and in practice the WSB5-40 is rated for 230 V AC single-phase (up to about 400 V AC in three-phase variants). It is therefore intended for building final distribution, the domestic switchboard and similar low-voltage networks — not for upstream or medium-voltage work. It must never be used above its rated operational voltage Ue.

The rated frequency tells you the supply AC waveform the breaker is calibrated for. Because the thermal release responds to RMS current and the magnetic release responds to peak current, both 50 Hz and 60 Hz supplies fall well inside the design window of a low-voltage MCB, so the same WSB5-40 can ship to 50 Hz Europe/Asia and 60 Hz Americas without re-engineering. It is not intended for DC systems or for frequencies outside the 50/60 Hz band.

Unlike a fuse, which must be physically replaced after it blows, an MCB like the WSB5-40 trips mechanically and is simply reset with the toggle once the fault is cleared. Unlike a plain switch, it automatically disconnects on overload and short-circuit, and it combines both functions in one DIN-rail enclosure. It also provides a visibly open contact position for isolation during maintenance.

The WSB5-40 is typically rated for a 6 kA short-circuit breaking capacity at 230 V AC, which is the standard figure for household MCBs and is adequate for the vast majority of domestic consumer units. That means it can safely interrupt up to 6 000 A of prospective fault current without being destroyed. If the board is very close to a large transformer, an engineering calculation should confirm the actual prospective short-circuit current at the board.

As a 40 A frame MCB it is generally used as a branch or final-circuit breaker rather than as the incomer. For a small domestic installation whose total load stays below 40 A it can double as a protective main switch, but for larger homes and commercial boards the main switch should be a higher-rated device such as a WSB1-125 or an MCCB. Always size the incomer breaker above the sum of the downstream breakers' trip settings with discrimination in mind.

The WSB5-40 is tested and certified to IEC 60898-1 (over-current protective MCBs for household and similar installations) and bears CE marking, indicating conformity with the applicable European Low Voltage Directive and EMC requirements. Many export variants are also tested to equivalent national standards such as GB 10963.1 in China. When ordering for a specific country, confirm the required certification on the certificate of conformity.

Yes, provided you pick the correct trip curve. A B-curve WSB5-40 is the natural choice for LED drivers, electronic ballasts and IT loads, because its lower instantaneous trip threshold gives faster protection against small short-circuits without being upset by capacitive inrush. Avoid a D-curve on purely electronic loads, as its 10–20 × In magnetic threshold can delay fault disconnection.

No. The WSB5-40 is a pure MCB: it protects only against overload and short-circuit. It does not detect earth leakage (residual current) and will not trip on a person touching a live part. For shock protection and fire protection against earth faults, pair it with a separate RCCB upstream or select an RCBO variant that combines MCB and residual-current protection in one unit.

Store it in its original packaging in a dry, dust-free location within the manufacturer's stated temperature range (typically −25 °C to +60 °C). Install it on a 35 mm DIN rail inside an enclosure with the correct IP rating for the location, torque the terminals to the value on the nameplate, and never exceed the number of conductors or the wire size listed. Because it is a sealed, non-user-serviceable device, the only routine maintenance is an annual visual check and a manual trip/reset exercise to confirm the mechanism still moves freely.