Review on Adjustable AC Current Sensing Switch: SZC23 No AL-CH Model, 0.2A-30A Range by Adam Townsend

Worked as advertised. Used it to sense current to fan on gas furnace to turn on my humidifier. After reading negative reviews of it not working, I tested it first on my workbench. Fed a single wire of a 120V line through the device to a simple 100W incandescent light bulb (measured draw of 0.82 amps) and turned sensitivity screw counter clockwise to L which apparent means needing lower current to activate till light went red and switch closed (checked with continuity checker). So L mean lower current to activate and H means higher current required to activate which is the opposite of the typical meaning of "sensitivity" lol. Then hooked into a switch box with fuse going to my furnace (see photo) Ran a black wire carrying the switched hot wire through the device. With just fan running turned sensitivity multi turn screw pot clockwise toward H to turn off switch (light goes green) and then backed up to L to light just turned red so just sensitive enough to pick up about 4 amps draw of my furnace fan. (When fan and furnace both on it draws about 6 amps) Switch is wired in series with my humidistat wire so both must be on to activate my humidifier relay which uses 24V AC and draws about 80 mA well within the 500 mA maximum current of the switch. Would give it 5 stars but should have a small inserted in the package single page of directions and help. Its counterintuitive from sensitivity screw clockwise to H requiring more current to activate switch (less sensitive) to red for relay on and green for relay off (but senses some current or neither light would be on) opposite of traffic lights lol! Also wish you didn't have to bring a power line carrying the load through the device, but that is because it also powers the device not needing a battery or other power source to run the relay. So be sure you have an accurate clamp on AC amp meter to work with this device as well as a basic digital or meter volt ohm meter.