Chinese Factory 63A to 125A 2p Wsb1-125 Series Miniature Circuit Breaker

The WSB1-125 2P is a two-pole version of Westhomes' high-current MCB series, rated from 63 A to 125 A. It bridges the gap between small household breakers and the larger 3P/4P three-phase devices: it is used on single-phase high-current circuits where both line and neutral must be switched and protected — for example a 100 A single-phase main switch, a large residential air-conditioner feed, or a single-phase sub-main to an apartment or shop.

The series covers 63 A, 80 A, 100 A and 125 A rated currents within the same 125 A frame. Choose In by the load: 63 A for a single-phase sub-main feeding a modest apartment or small office, 80–100 A for a medium-sized house or retail shop with several high-power appliances, and 125 A for a large single-phase service entrance or a heavy-duty commercial branch. In every case, In must not exceed the cable's ampacity Iz, and the breaker must be able to withstand the actual incoming fault current.

On a 2P breaker, both L and N are switched and both poles carry the overcurrent trip mechanism, so the circuit is fully isolated when the breaker is off. This is a safety requirement for a main switch: it prevents the neutral from remaining live while the line is open, which is a common shock hazard during maintenance. A 1P breaker leaves the neutral connected at all times and is not accepted as a main protective device in most wiring regulations.

Connect the incoming phase (L) to the top L terminal and the incoming neutral (N) to the top N terminal, then route the load-side L and N out from the bottom terminals to the outgoing sub-circuits. Observe the polarity markings on the body and tighten each screw to the specified torque. Because the conductors are large (16–35 mm²), use properly sized lugs or ferrules and keep the bends within the cable manufacturer's minimum bend radius.

It is rated for 230 V AC (single-phase) at 50 Hz or 60 Hz, with an insulation voltage that allows use on standard low-voltage networks worldwide. The 230 V figure is the phase-to-neutral voltage of a 400 V three-phase system, so the 2P WSB1-125 can be tapped off any single phase of a three-phase supply. It is not rated for 400 V single-phase (which would require a 2P connected across two phases — verify the datasheet before doing so).

The WSB1-125 2P is typically rated at 6 kA short-circuit breaking capacity at 230 V AC, matching the rest of the series. That is adequate for most domestic and small-commercial main boards, because the impedance of the supply cable usually limits the fault current to well below 6 kA. If the board is fed directly from a nearby large transformer, have a short-circuit calculation performed and select a 10 kA version if required.

A 2P WSB1-125 MCB is smaller, cheaper, DIN-rail mountable and perfectly adequate for 63–125 A where the fault current is below 6 kA. An MCCB is larger, more expensive, offers field-adjustable trips and higher breaking capacities (10 kA–25 kA+), and is used when the fault current exceeds 6 kA or when adjustable long/short-time settings are needed. For a typical 63–125 A single-phase main switch the MCB is the standard, cost-effective choice; move to an MCCB only when the engineering analysis says so.

Yes. A 7 kW single-phase EV charger draws about 32 A, and a 11 kW charger can draw up to about 48 A; a WSB1-125 2P at 63 A provides ample upstream protection with headroom for future upgrade to an 11 kW or 22 kW unit. Pair the MCB with a Type A or B RCD upstream (or use an RCBO) for earth-leakage protection, and size the charging cable accordingly. The C-curve WSB1-125 handles the charger's electronics inrush without nuisance tripping.

Instantaneous tripping on switch-on almost always means a hard short-circuit downstream (a pinched cable, reversed L/N at a socket, or a failed appliance), an incorrectly sized cable where the breaker has been fed upside-down, or a defective breaker from the box. Disconnect all outgoing circuits and re-energise one at a time to localise the fault. If the breaker still trips with all outgoing loads disconnected, the breaker itself is faulty and should be replaced under warranty.

Yes, the WSB1-125 series is type-tested to IEC 60898-1 and carries CE marking, which is the standard requirement for export to Europe and most global markets. As a sealed modular device it requires no scheduled maintenance; once a year operate the handle manually to confirm the mechanism moves freely and inspect the terminals for overheating. Re-torque the screw terminals after the first year in service, and after any major short-circuit trip have the breaker inspected by a qualified electrician.