The AC current sensing switch is a clever device. When you pass one line of the sensed AC through the hole in the switch, it generates enough power internally to control a solid state switch and hence close K1 to K2, but it can't handle much of a load, so you might have to use it to drive a relay capable of higher loads. This would also give better isolation from mains voltage. Solid state switches are susceptible to damage by spikes. I wouldn't use this, but if I did, I would put it in a fused earthed metal box and use the device to drive a double pole mains relay. The box would have a master socket and a slave socket. My Nilfisk Alto vacuum has a current sensed switched socket which is rated at 1800W Max.