Westhomes Factory Price Wsb9sz-125 AC Electrical Miniature Circuit Breaker 6-100A MCB 1p

A 1-pole MCB protects one phase (live) conductor on a single-phase circuit. It is the most common protective device for residential lighting, socket outlets, and individual appliance branches in commercial distribution boards. It switches and protects the live conductor; the neutral remains connected unless an additional device isolates it.

Load current flows through a bimetal strip that bends under sustained overload and trips via a latch, giving time-delayed overload protection. Above the magnetic threshold (3–5, 5–10, or 10–20 × In depending on curve), a solenoid plunger fires instantly to clear short circuits. This dual action protects both cables from thermal overload and installation from destructive fault currents.

Apply Ib ≤ In ≤ Iz: first work out the design current Ib of the load, then choose the next higher standard rating In whose cable ampacity Iz comfortably exceeds it. Common guidelines are 6A for lighting spurs, 10–16A for general lighting, 16–20A for sockets, 32A for cookers and showers, and 63–100A for sub-mains.

Curve B trips magnetically at 3–5 × In (sensitive, for resistive loads), Curve C at 5–10 × In (general purpose, for sockets and mixed loads), and Curve D at 10–20 × In (for motors and transformers with high inrush). Always pick the lowest curve that does not nuisance-tip on normal start-up current.

Connect the incoming supply (line) to the top terminals marked "Line" and the downstream circuit to the bottom terminals marked "Load". The arc chute and magnetic blow-out are tuned for this direction; back-feeding can reduce breaking capacity and is generally not permitted unless the datasheet explicitly allows it.

It is rated to a declared short-circuit breaking capacity (typically 6 kA, sometimes 10 kA) shown on the nameplate. Before installation, confirm the prospective short-circuit current at the panel — if it is higher than the breaker rating, add upstream current limiting or specify a higher-breaking-capacity model.

Yes, the handle can be used as a functional switch to isolate the circuit for maintenance, but it is not a substitute for proper isolation with a lockout. The contacts are designed for a finite number of operations; routine switching should be infrequent, and any trip under fault should be investigated rather than simply reset.

Probably not. A compressor draws starting current, and a borderline breaker or a too-sensitive curve can nuisance-trip. Check the actual measured current, confirm the cable rating, and consider moving from a B curve to a C curve. If it still trips below In on a stable load, have the breaker bench-tested for a degraded bimetal.

It is used on single-phase final circuits: lighting, socket outlets, small kitchen appliances, HVAC auxiliary circuits, and individual equipment branches. It is the workhorse device in residential consumer units, office distribution boards, and machine control panels where one phase needs independent overcurrent protection.

Yes. As an AC miniature circuit breaker in the 6–100A range, it is manufactured and tested to IEC 60898-1 and affixed with the CE mark. The nameplate lists Ue (e.g. 230 V), In, the tripping curve letter, the rated short-circuit capacity, and the standard number for traceability during inspection.