Schneider A9R51240: a 2-pole, 40A, 30mA Type A RCCB

A9R51240 is a residual current circuit breaker (RCCB) from Schneider Electric’s Acti9 iID range: a two-pole device rated 40A with 30mA sensitivity and Type A detection. It trips the circuit when it senses earth leakage, protecting people from electric shock.

What the ratings mean

The numbers in the part’s description describe separate properties, and they’re worth keeping straight when you order:

• 40A rated current (In) is the load current the device is built to carry continuously. It has nothing to do with the 30mA figure.
• 30mA sensitivity (IΔn) is the earth-leakage current the device responds to. 30mA is the level used for shock protection on final circuits; the Acti9 iID range also comes in 10mA, 100mA, 300mA and 500mA versions for other jobs.
• 2P means it switches two poles — live and neutral — on a single-phase circuit. Four-pole versions exist for three-phase work.
• Type A describes the waveform of residual current the device responds to. The Electrical Installation Guide’s comparison of RCD types puts Type A over sinusoidal AC residual currents plus pulsating DC residual currents, where Type AC covers sinusoidal AC only and Types F and B extend further.

It’s worth knowing the Type letter is unrelated to an MCB’s trip curve — a “C curve” is a magnetic trip characteristic, as Schneider explains. Because current rating, sensitivity and Type letter are independent, checking the exact part number is the reliable way to get what you intend.

One more distinction: an RCCB carries no overcurrent protection of its own. An MCB or fuse ahead of it handles short circuits and overloads, so a board needs both devices working together — unlike an RCBO, which combines the two.

Physical detail

Schneider’s product page lists A9R51240 for protection against electric shock by direct contact, suitable for residential isolation under IEC 61008-1 and IEC 61008-2-1, with a red mechanical earth-fault indicator on the front face and compatibility with the Acti9 captive padlocking device.

The KVC catalogue record gives the planning figures: it’s 36mm wide (four 9mm modules) and 91mm high, clipping to a 35mm DIN rail, running at 220–240V AC 50/60Hz. Endurance is quoted at 15,000 electrical and 20,000 mechanical cycles. One naming quirk worth knowing: KVC’s page heading reads “A-TYPE” while its URL slug reads “AC-TYPE”. The part number and the manufacturer both identify A9R51240 as Type A, so trust the part number over the slug.

The green Schneider retail carton is the quickest way to confirm you have the right device. Its label prints A9R51240, Acti9 - iID, 230V/240V - Type A, 2P, 40A and 30mA-A — matching the manufacturer’s identity. Some seller listings add their own “original” stamps and shop badges over the photos; those are the seller’s marketing, not part of the package printing.

Where it is listed in Malaysia

Several Malaysian sellers list A9R51240 online:

Those are reference prices for the item, not delivered quotes, and they don’t confirm that a branch has stock on a given day — check with the seller for a current figure.

If you’re weighing pole count or current rating, the Acti9 iID comparison sets the four related models side by side.