Device overview

The Schneider Electric Acti9 iEM3255 (A9MEM3255) is a DIN-rail energy meter for installer-led submetering, multi-tariff monitoring and building-management systems. Unlike a direct-connected meter, it measures through external current transformers, so the CT ratio and wiring must match the monitored circuit.

Core characteristics

  • External 1 A or 5 A CT inputs, with the primary measurement range programmable up to 32,767 A
  • 1P+N, 3P and 3P+N networks
  • 100-277 V line-to-neutral or 173-480 V line-to-line, 50/60 Hz
  • Active-energy Class 0.5S and Class C accuracy, with MID certification
  • Signed four-quadrant active, reactive and apparent energy
  • Current, voltage, active power and reactive power measurements
  • Four tariffs, one digital input and one digital output

Installation and sensor setup

The meter occupies five 18 mm DIN modules (90 mm total) and is intended for an indoor electrical panel. It does not include a clamp set: the installer must select compatible 1 A or 5 A secondary CTs, configure the correct primary ratio, observe CT polarity and complete voltage wiring. The stored 32,767 A value is the programmable primary CT range, not current that passes through the meter terminals.

Compatibility and data access

RS-485 Modbus RTU provides local register access without a Schneider cloud service. It can feed a BMS, data logger, industrial gateway or another Modbus host. Home Assistant can read it through the official generic Modbus integration when suitable RS-485 hardware and manual register mappings are configured; there is no native one-click iEM3255 integration.

Solar import and export measurement

Signed four-quadrant metering separates energy direction, so the device can record imported and exported energy when the CT orientation and register mapping are correct. This helps with solar generation, grid exchange and submetering analysis, but the meter does not itself control an inverter or enforce an export limit.

Suitable use cases

The iEM3255 is most useful where direct-fed meters are unsuitable because circuit current is high, where Class 0.5S accuracy matters, or where an existing Modbus/BMS workflow is already available. It is a stronger fit for professional panels and commercial or advanced residential monitoring than for buyers seeking a bundled app and clip-on DIY installation.

Advantages and limitations

Its main strengths are broad CT scaling, four-quadrant data, local Modbus, MID certification and strong measurement accuracy. The tradeoffs are installer-only wiring, separate CT procurement, manual commissioning and no built-in consumer cloud dashboard. CT class, ratio, placement and wiring can affect installed-system accuracy even though the meter itself carries Class 0.5S specifications.

Purchase and official sources

Schneider Electric's UK product page listed A9MEM3255 at GBP 456.10 during the 2026-09-10 CST review. Confirm local stock, the required CTs, certification, tax and delivery before ordering. Technical values were checked against Schneider Electric's exact product datasheet and iEM3000 Modbus manual.