My control panel does not have an on/off switch. When it is plugged in, it is "on". I do have an E-stop circuit which controls a contactor that shuts off power to the entire panel. Is there a downside to putting a simple on/off switch in the E-stop circuit that controls the main contactor? I have seen more elaborate on/off arrangements using a momentary switch but I don't understand why that is necessary. What am I missing?