I have searched google and the forum, but I think there is too much information missing from my general understanding of electronics to know what to look for. To put it simply, I want to know how to put a relay in a 120 VAC circuit just before an array of switches (Product 482 at Adafruit) so that I might be able to power 'everything' from one bank of switches. I know I have 2 dedicated 30 amp services running to my hobby studio, and I will be using those in order to centralize all switching and control. When all is said and done, I am imagining approx 40 switches on one panel.

This schematic represents all my noodle can handle with regards to this project - please help me complete it

 

I know I have 2 dedicated 30 amp services running to my hobby studio, and I will be using those in order to centralize all switching and control.

120 VAC 30 Amp service requires as a minimum AWG 10 wire. So my read is you just want a single relay to switch a 120 VAC 30 Amp service? You do not switch the neutral and if you want I would use a latching relay circuit with 1 each N/O (Normally Open) and 1 each N/C (Normally Closed) push button. There is an endless number of relays you can use from any number of supply houses, here is one example from Grainger Supply. Here is a basic overview of a latching relay circuit where one set of relay contacts is used to "latch" the relay.



SW1 is a N/C push button and PB2 is a N/O push button. RY1 is a DPST or if you like a 3PST relay and in your case with a 12 VDC coil. Would something like this be what you are looking for? This would also be hard wired to your mains unless you have a 30 Amp NEMA rated plug and receptical..

Ron