Westhomes Wsb9-80 Miniature Air Low Voltage Circuit Breaker 2p with AC230V400V 50Hz/60Hz

The WSB9-80 2P is a double-pole miniature circuit breaker rated up to 80A, used to protect single-phase circuits that require simultaneous switching of line and neutral. Typical uses include the main switch of a single-phase distribution board, protection for large single-phase appliances (electric showers, cookers, air conditioners, water heaters), sub-mains to outbuildings, and feeders to sub-panels. Because it opens both L and N, it provides full isolation for safe maintenance.

A 1P MCB switches only the line conductor and leaves neutral connected; a 2P switches both line and neutral together. Wiring regulations in many countries require double-pole isolation for main switches, and it is strongly recommended for circuits feeding equipment that may be touched or serviced. Even if neutral is not considered "live," a 2P breaker removes all voltage from the downstream circuit, preventing shock risk from crossed neutral or broken neutral faults.

"Air" means the breaker uses atmospheric air as the medium to extinguish the arc that forms when contacts open under fault current. Unlike oil or gas circuit breakers, an air MCB channels the arc through a stack of metal plates (arc chute) that split, cool, and de-ionize it until it can no longer sustain. This is the standard interruption method for low-voltage MCBs: simple, maintenance-free, and reliable over many operations.

The WSB9-80 frame is offered across a range of rated currents, commonly 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A, 63A, and 80A, in B, C, and D trip curves. The 80A version is the top rating of the frame and is typically used as a main switch or heavy feeder, while the lower ratings serve final circuits such as sockets, lighting, and appliances. Confirm the available ratings and curves when ordering for a specific project.

Like other Westhomes MCBs, it uses a thermal-magnetic trip: a bimetallic strip bends slowly under mild overload to trip after an inverse time delay, and an electromagnetic solenoid releases near-instantly when a large short-circuit current flows. On a 2P device, both poles are mechanically cross-linked, so whichever pole senses the fault opens both contacts. This ensures the load is fully isolated whether the fault is between L and N or within the load.

Although it is a 2-pole device, its 230V/400V rating means it is built to IEC 60898-1 voltage standards. In practice, a 2P MCB is almost always used on a 230V single-phase circuit (L–N). Its internal insulation and separation are rated such that it can also be used across two phases of a 400V three-phase system in special applications, but this is unusual; for standard three-phase loads, select the 3P version. Always verify the system voltage and wiring configuration on the rating plate.

It clips onto a standard 35mm DIN rail using the integrated rail catch. Open the front cover if accessible, hook the top edge onto the rail, and press the bottom until it clicks into place. Remove it by pulling the bottom release tab downward with a screwdriver. Connect the incoming L and N to the top terminals, and outgoing L and N to the bottom terminals, observing the correct polarity. Tighten to the specified torque and ensure the earth cable of the panel remains connected to the panel's earth bar.

Air conditioners and refrigeration compressors draw a locked-rotor starting current of 5–7 times running current for a fraction of a second. A B-curve MCB (instantaneous trip at 3–5 In) can see this as a short circuit and trip. The fix is usually to select a C-curve (5–10 In) or D-curve (10–20 In) breaker sized to the compressor FLA, rather than to the maximum cable rating. A properly sized C-curve WSB9-80 will ride through the starting inrush while still clearing a genuine short circuit.

Most WSB9-80 frames are designed to accept side- or front-mounting accessories such as auxiliary contacts (OF), fault-signal contacts (SD), shunt releases (SHT) for remote tripping, and undervoltage releases (UVR). These accessories snap onto the side or top of the breaker without changing its DIN-rail footprint. They are commonly used in commercial and industrial panels to provide remote status indication or emergency stop wiring. Confirm accessory compatibility when ordering.

Once or twice a year, a qualified electrician should inspect the breaker for physical damage, check terminal torque, exercise the operating handle a few times, and verify that it trips freely without sticking. Because this breaker often sits at the origin of an installation carrying 63–80A, any discoloration, burning smell, or warmth on the case is a sign of a loose connection or overload and requires immediate investigation. After any short-circuit operation, the breaker should be inspected or replaced, even if it still appears functional.