OK. I did buy an E-Stop push button and a contactor rated to handle all of the power coming into to the control panel and is part of my build.
The main feed in my house panle is from a 50 Amp GFIC breaker, so that is protected.
My original question was limited strictly to cutting power to the individual elements, not as an E-stop. That is a separate deal as described above..
A little off my topic, but I am planning on having 2 boxes. One for High voltage and one for low voltage. There will be some mixing since my PID's need 120 V and I thought I would put the 12 V and 24V transformers in the low voltage box with the PID's, temp probe connectors, selector switches, flow and float switch connectors. The SSR's, contactor, relays, power to the elements and pumps in the high voltage box.
My reasoning for doing this is the limitations of the sizes of the boxes I have and trying to minimize EMF (or whatever that is)
Any thoughts ?