Current sensing device

The invention provides contactless current sensing for a multi-wire electric cord based on measuring spatial variations in the magnetic field surrounding the cord. A current sensing device according to the invention includes a plurality of magnetometers, each adapted to measure the local magnetic flux density. Advantageously, such current sensing device is clamped around a portion of the electric cord. Embodiments suited for situations where there is a risk of inadvertent separation of the device from the cord include fastening means that cannot be disengaged by unarmed hands. The device may operate independently or form part of a current sensing system, wherein one or more devices - each associated with a particular electric appliance - communicate wirelessly with a central unit. The central unit may emit an alert message when unintended use of an appliance is detected.