Magnelab's SCT-3000 Series split-core current sensors "sense" AC current up to 3000 Amps passing through the center conductor. Split-core transformers are ideal for installation on existing electrical wiring by snapping around the conductor.
The SCT series have a self-locking mechanism.
SCT-3000 models:
Magnelab Split-Core AC Current Sensor SCT-3000 (0.333V output)