C.T. clamp / Current transformer clamp

Also known as Current transformer clamp, CT clamp

Clip-on current transformer sensor used by monitors, inverters and chargers to measure AC current for import/export monitoring and load control.

A CT clamp, or current transformer clamp, is a clip-on sensor fitted around a single AC conductor so an inverter, charger or monitor can estimate current without being wired in series with the circuit. In home energy systems the reading is often used to work out grid import or export, solar generation, EV charger load balancing or heat pump electricity use. The clamp must be on the right conductor and fitted the right way round because putting it around a whole multicore cable can cancel the measurement and reversing it can make import look like export. Consumer-unit work should be left to a competent installer, especially where the clamp sits near live mains conductors.