Magnelab's SCT-1250 Series split-core current sensors "sense" AC current up to 200 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-1250 models:
Magnelab Split-Core AC Current Sensor SCT-1250 (0.333V output)