Shelly Current Transformer 120A

The Shelly Current Transformer 120 A is a robust clamp-style energy monitoring accessory intended for use with compatible smart-home energy meters. Its split-core design allows it to clamp around a single conductor — such as a main feed or heavy-duty circuit — without interrupting wiring, offering a safe and non-intrusive solution for current measurement. Designed for both domestic and light-commercial contexts, this transformer enables accurate tracking of electrical load on high-current circuits.

With a maximum primary current rating of 120 A, the transformer is well suited for monitoring entire household supply lines, large appliances, heating circuits, or distribution board outputs. When paired with an appropriate energy-monitoring module, it delivers real-time data on current draw and energy consumption. This ability to observe circuit load makes the unit valuable for energy management, load balancing, safety monitoring and automation scenarios.

Key Features

• High-Capacity Current Measurement: Capable of measuring currents up to 120 A — suitable for whole-house feeds, heating circuits or heavy-duty equipment.
• Split-Core Clamp Design: Opens and closes around a conductor without disconnecting wiring, enabling easy retrofit installation even in live circuits.
• Non-intrusive and Safe Installation: No need to cut or rewire cables; the clamp simply encloses an existing conductor for measurement.
• Compact and Space-Saving Form Factor: Slim clamp body fits within consumer units, distribution boards or service panels without occupying excessive space.
• Compatibility with Energy-Monitoring Modules: Designed to interface with compatible energy meters to provide real-time current and energy data for monitoring, logging or automation tasks.

Technical Specifications

• Rated primary current: 120 A (AC)
• Core type: Split-core current transformer
• Conductor aperture: Suitable for single conductors up to typical mains cable diameters
• Application: Current measurement only — requires a compatible energy-monitoring module for data processing and display
• Installation method: Clamp around live conductor; no need to cut or disconnect wiring

Use Cases

• Monitoring total current draw of a household mains feed or distribution board to track consumption or detect overloads
• Measuring power usage of high-demand circuits such as heating systems, boilers, water pumps or heavy appliances without intrusive wiring changes
• Integrating with a smart-home energy-monitoring system to log daily, weekly or monthly energy usage for budgeting or efficiency analysis
• Using in renewable-energy or solar installations to track feed-in or draw-out currents for safety, monitoring and load management
• Implementing protective automation — such as alerts or load shedding — triggered when current exceeds defined thresholds to enhance safety and prevent overload damage