Product review (5 stars): Using the current sensing switch properly
NOTE:  I don't have the product but chose this rating so those of you who would rate it poorly because of improper use of the switch would be more likely to read it.

Since some comments have indicated the current sensing switch did not include adequate instructions and did not work or worked erratically I felt I should point out a few things that might not be obvious:

Most American dryers are connected to 240 VAC which is two 120 VAC circuits of opposite phase but unlike most 240 VAC appliances they use one 120 VAC leg to run the motor and only use both (240 VAC) to go to the heating element which isn't on all the time.  For this to work properly the electrician needs to experiment to find which leg goes to the motor and use that one to go through the hole in the sensor or if the neutral wire is easily accessible it can be run through the hole in the sensor toroid or donut.  Otherwise the fan will turn off any time the heating element isn't energized.

Also only one wire should go through the hole in the sensor. It senses a magnetic field caused by the current flowing and if you run both wires through it the current flowing in opposite direction cancels the magnetic field and the switch will never detect it and never turn on.

I hope this will help eliminate some of the problems buyers have had using the current sensing switch.