WSB5-40 1P+N Miniature Circuit Breaker MCB 1 Phase Nuetral

The WSB5-40 combines a thermal release and an electromagnetic release inside one molded housing. Under mild overload the current heats a bimetallic strip that bends and trips the mechanism after a time delay, while a large short-circuit current magnetically drives a solenoid that trips almost instantaneously. Both actions free a spring-loaded mechanism that opens the contacts and extinguishes the arc in a compact chamber, isolating the protected circuit.

A 1P+N device has two terminals (phase L and neutral N) but only the phase pole carries the full thermal-magnetic overcurrent protection; the neutral pole is mechanically linked and opens together with L for isolation. A true 2P breaker has full protection on both poles. On the WSB5-40 1P+N you get simultaneous disconnection of L and N in a compact 2-module width, which is ideal for single-phase final circuits where neutral isolation is wanted without paying for a second protected pole.

Connect the phase (line) conductor to the marked L terminal and the neutral conductor to the terminal marked N, following the "top-in / bottom-out" convention shown on the wiring diagram on the body. Always route the supply to the top terminals (line side) and the load to the bottom terminals, and tighten the torque to the manufacturer's specified value. The label polarity must be respected: swapping L and N can defeat the intended overcurrent sensing and leaves the protected circuit wrongly referenced when the breaker is off.

The "40" denotes the 40 A rated-frame (frame size) of the series, not necessarily a single fixed current. Within that frame the WSB5-40 family is offered in the usual 6 A, 10 A, 16 A, 20 A, 25 A, 32 A and 40 A current ratings, each with its own calibrated trip setting. When ordering you must specify the exact In (for example 16 A or 32 A); the 40 A frame simply tells you the maximum current that housing can carry and the terminal/cable capacity available.

Yes. The WSB5-40 is designed as a low-voltage AC MCB for 50 Hz or 60 Hz systems, with a rated insulation and operational voltage around 230 V AC between phase and neutral (up to 400 V AC in the series family). Because the magnetic and thermal trip characteristics are essentially independent of supply frequency in this range, the same breaker can be used on European 230 V/50 Hz, Asian 220 V/50 Hz or North American-style 240 V/60 Hz single-phase supplies without de-rating.

The WSB5-40 series is commonly offered in B, C and D curves, which differ only in the instantaneous magnetic trip threshold. B-curve trips at 3–5 × In and is suited to lighting and resistive loads; C-curve trips at 5–10 × In and covers general socket and mixed loads; D-curve trips at 10–20 × In and is used for high inrush loads such as small transformers or motors. For a typical residential branch circuit choose B for lighting and C for sockets, and avoid D unless the load really has high starting current.

It snaps onto a standard 35 mm DIN rail (EN 60715) just like other modular MCBs, so it fits the vast majority of consumer units, distribution boards and panel boxes used worldwide. The 1P+N WSB5-40 occupies two DIN modules of width (about 36 mm) on the rail, compared with a single 18 mm module for a 1P-only device. No special mounting hardware is needed; simply hook the top onto the rail and push the bottom until it clicks, then wire the line and load conductors.

Start from the design current of the load (Ib), then select a rating In such that Ib ≤ In ≤ Iz, where Iz is the current-carrying capacity of the cable (after grouping, insulation and ambient-temperature corrections). As a rule of thumb, a 1.5 mm² copper cable is protected by a 10 A or 16 A breaker, a 2.5 mm² cable by a 20 A or 25 A breaker, and a 4 mm² cable by a 25 A or 32 A breaker. Always cross-check the cable manufacturer's ampacity table and local wiring regulations rather than guessing.

"Nuisance" or unwanted tripping is usually caused by an ageing or faulty appliance (motors with worn brushes, heaters with element degradation), a mildly damaged cable with intermittent leakage, or a breaker that has been de-rated because the board is crowded and hot. It can also occur if the trip curve is too tight for the inrush of the load (e.g. a C-curve breaker on a motor-driven load). Isolate circuits one by one to find the faulty branch, and check whether the ambient temperature in the board is above the reference 30 °C.

The WSB5-40 is manufactured to IEC 60898-1 (the international standard for miniature circuit breakers for household and similar installations) and typically carries CE marking, which is the prerequisite for sale in the EU and many other markets. Being a sealed, maintenance-free device, it requires no servicing; a simple annual check of the trip/test handle and a visual inspection for overheating or discoloration is sufficient. If it ever trips on a genuine short-circuit fault that has cleared, it can simply be reset, but repeated fault operations should be inspected by a qualified electrician.