ABB B21 Single-Phase Energy Meter

The ABB B21 is a compact Class 1 single-phase electronic energy meter designed for residential and small commercial sub-metering applications, measuring active energy in both import and export directions with full bidirectional capability that makes it inherently suited to solar net-metering installations. The B21 mounts on a 4-module DIN rail section in standard distribution panels and can be connected either directly to the circuit up to 80 A or via a 5 A secondary current transformer for higher-current circuits, giving panel builders flexibility across the full range of single-phase sub-metering requirements from a single meter model. A tamper-evident sealing cover over the terminal block prevents unauthorised circuit modification without leaving visible evidence, satisfying the anti-tamper requirements of building operators and utility-grade sub-metering programs.

The optional RS-485 Modbus RTU communication module transforms the B21 from a standalone local indicator into a networked energy data point within a building energy management system (BEMS) or automated meter reading (AMR) infrastructure. With Modbus RTU, the B21 reports instantaneous voltage, current, power factor, and accumulated active energy to building controllers and energy management platforms at user-configurable intervals, enabling tenant billing, energy auditing, and sustainability reporting without manual meter reads. The RS-485 bus can carry up to 32 B21 meters on a single two-wire network at distances up to 1200 metres, covering the metering needs of an entire apartment tower, commercial building floor, or industrial warehouse from a single communication cable run to the building management system.

Saudi Arabia's building sector is rapidly adopting smart sub-metering as a combination of regulatory driver and commercial necessity. The Saudi Building Code requires individual energy metering for each commercial and residential tenancy unit in multi-tenant buildings, and the Vision 2030 energy efficiency targets require building operators to report consumption by floor, zone, or tenant as part of green building certification programs. Residential compound operators and commercial tower property managers in Riyadh, Jeddah, and the Eastern Province are deploying B21-based sub-metering systems to enable fair energy cost allocation to tenants and to identify high-consumption areas for energy conservation measures. The growing Saudi residential solar sector — where homeowners connect rooftop solar under ARAMCO and NWC compound distributed energy programs — uses the B21's bidirectional measurement to record both consumption and solar generation for net-metering reconciliation.

Razz Middle East stocks B21 meters in standard and Modbus-equipped versions for immediate delivery across Saudi Arabia. We supply to panel builders, BEMS integrators, and facilities management companies, and our engineers provide Modbus configuration, CT ratio programming, and BEMS integration support for complete sub-metering system installations.