What is the device now found on the plugs of such appliances as hair dryers?

The large box-like device found on the ends of some appliance cords could be an appliance leakage circuit interrupter (ALCI), an immersion detection circuit interrupter (IDCI) or a ground fault circuit interrupter (GFCI). Though they work in different ways, they all protect the user against accidental electric shock and electrocution by acting immediately to shut off power to the appliance upon the detection of a “leak” of electric current as may happen when a hair dryer falls into a sink full of water. Even with these de-vices, if that happens, unplug the device or shut off power to the circuit before reaching in to retrieve the appliance.