A9S4P040 | Acti 9 Isolator xSW 4P 40A 1.25kA 415V AC – Schneider Electric

Q: What is the significance of the 40 A rating on the A9S4P040?

A: The 40 A rating is the device’s maximum continuous current carrying capacity under specified conditions (typically 40°C ambient). For circuit design, use 80% of this value as the design current to allow for derating due to grouping, temperature, and future load growth.

Q: What does the 1.25 kA breaking capacity on the A9S4P040 mean in practice?

A: Breaking capacity (1.25 kA) is the maximum prospective short-circuit current the A9S4P040 can safely interrupt without damage. Before installing, verify that the prospective fault level at the installation point does not exceed 1.25 kA — this is checked using a fault level calculation or from the upstream transformer impedance data. Installing a breaker with insufficient breaking capacity is a serious safety violation.

Q: Can the A9S4P040 make and break load current, or is it for isolation only?

A: This is a switch-disconnector (not a pure isolator), meaning it is rated to make and break load currents up to its rated current under AC-22A or AC-23A utilisation categories. Pure isolators must only be operated on de-energised circuits. The Schneider Electric switch-disconnector can therefore be used for operational switching, not just maintenance isolation.

Q: How many padlocks can be applied to the A9S4P040 for LOTO safety?

A: The Schneider Electric switch disconnector supports up to 3 simultaneous padlocks on the OFF-position locking facility. This allows multiple contractors or maintenance teams to each apply their own padlock, ensuring the circuit cannot be re-energised until all teams have removed their lock — a critical requirement for multi-contractor LOTO procedures.

Q: After a short-circuit trip on the A9S4P040, can it be reset and reused immediately?

A: After a short-circuit trip, do not immediately reset the A9S4P040. First, identify and clear the fault. Then inspect the device — if there is visible arc damage, melted insulation, or the handle does not reset smoothly, the device must be replaced. The 1.25 kA rated breaking capacity is not unlimited — it is the maximum fault current the device can interrupt safely for a defined number of operations (typically 1–3 at full Icu rating). After any significant fault, factor replacement into your maintenance budget.