hey guys very cool ideas. I do have an electrical license and would be happy to lend info if needed.
My biggest hangup is relay size and electrical safety and code adherence.
Do you live in the US or Canada? There is zero use for me to actually get super excited about this project if I can't be 99.99% sure that it won't burn my house down.
I've been doing some reading, and I've found that the general consensus is that relays should only be pushed to 70% of their rated resistive load values. I also read that I should be very aware of handling split second huge current draws that might just pop the relay. Things like vacuums, electric kettles, etc. stuff that draws 5-10A resistive load, but when starting up the load can easily be 2-10x higher than that!
I had purchased some 15A @ 120VAC rated relays for $1.19 from Mouser Electronics, the contacts are quite small, and after reading up on it, I'm sure the only thing these ones can click on and off would be light bulbs.
So I need 30A @ 120V rated relays at minimum to make sure I have a high amount of room to work with. Only problem is that the price increases quite a bit.
I also found that there is a serious backing for the use of optoisolators for switching stuff like this. Separating the high voltage from the low voltage and stuff about not putting high and low voltage in the same box without some solid isolation.
If you can get back to me on wire gauging, relay size, and if you are in the US or Canada, a quick lesson on Elec code 101: How not to burn things, that would be great.