This device is not designed for inductive loads (solenoids, transformers, motors). The output waveform can be non-symmetrical causing the load core to saturate and the device impedance to drop. The result is it will draw more current and may overheat or blow the fuse inside the PD-3PCL.
The output when turned off with nothing plugged in is the full line voltage (120 volts AC) at a low current (0.5 mAmps). This device does not have an integral minimum load capacitance (MLC). It is also limited to 300 W for resistive loads. If you want to switch heavier loads consider connecting a high current solid state switch rated for 120 V ac input (for example https://www.amazon.com/Opto-22-Contr..._1492468880457). You will also need to parallel a small capacitance (0.15 uF 600 V film) across the solid state switch input to pull the off state PD-3PCL output to less than 10 VAC. The solid state switch will need to be enclosed to reduce the risk of electric shock and it will need a heat sink for higher current loads. You will also want to change the PD-3PCL to on/off only (you cannot dim loads using the solid state switches).