WH5-125 Series Single Pole Isolator Switch

A single pole isolator is a one-module DIN-rail switch that opens one conductor — normally the phase (live) — when the handle is turned OFF. It provides a visible break on the live side of the circuit while the neutral remains connected to the panel neutral bar. It is the most compact and economical way to add a local on/off isolation point.

Yes. A 1P isolator breaks only the phase. The neutral conductor continues straight through to the load on the neutral bar. This is acceptable for branch-circuit isolation where the installation's main switch already isolates neutral, but it is not sufficient as the sole means of isolation for circuits that must be fully dead.

Yes, as a switch-disconnector it can make and break its rated operational current (typically 125 A at AC-22A). It is intended for routine switching of normal load, not for interrupting short circuits. Upstream overcurrent protection must clear any fault.

125 A is the maximum continuous current the single pole can carry through its closed contacts. At 230 V this corresponds to roughly 28.75 kW of single-phase load. Because only one pole is switched, the downstream neutral must be sized for the same current and isolated elsewhere if full isolation is required.

A 1P MCB automatically trips on overload or short circuit; a 1P isolator does not. The isolator is a simple manual switch with no bimetal or solenoid. It is selected for isolation and load switching; the MCB is selected for protection. They are often installed in series, with the MCB upstream or downstream as required by the circuit.

Connect the incoming phase to the top terminal marked 1 (LINE), and the outgoing phase to the bottom terminal marked 2 (LOAD). The neutral bypasses the isolator and lands on the neutral bar. Use a copper conductor sized to 125 A (typically 25–35 mm²), strip to the marked depth, and tighten the screw terminal to the specified torque.

Yes, the handle has a padlock hole in the OFF position, allowing padlocks to be applied for LOTO. Because only the phase is isolated, also verify that any other sources of voltage (back-feed, parallel neutral paths, or remote supplies) are isolated before touching the load side.

It is type-tested to IEC 60947-3, which covers switches, disconnectors, and switch-disconnectors up to 1000 V AC. This includes making and breaking capacity, isolation distance, temperature rise, and mechanical endurance. The CE mark confirms compliance with EU Low Voltage Directive requirements.

A 1P isolator is generally not used as the main switch of a single-phase installation, because it does not isolate the neutral. It is better suited to local branch-circuit isolation — e.g., switching off a specific heater, pump, or piece of equipment before servicing. For a main isolator, choose a 2P (or 4P on three-phase) device.

Common uses are local isolators for water heaters, pumps, fans, air conditioners, lighting sub-circuits, HVAC and machinery on/off switches, solar PV combiner-box phase isolation, and any DIN-rail panel where a compact single-pole disconnect point is needed downstream of the main switch.