I've got a detached barn/garage that has an existing 2 wire cable running to the lights on the outside. Its attached to a 3 way switch in the house and another 3-way switch in the barn. I'm finishing the barn into an office and we are working on re-wiring including adding another light and another 3-way (i guess 4-way now) switch to this circuit. Low and behold when we went to do the wiring we discovered it a 2 conductor cable running from the house. A few years ago i installed a Z-Wave switch in both the barn and house location so I am guess those are talking to each other over the air which allows this whole thing to work. When i installed those switches i'm sure i would have simply replaced the old wires in the new switch hot, neutral, and traveler terminals. I'm going to not hurt my brain to figure out how this ever worked - zwave or not. My question is - is there a way i can run multiple lights and 2 switches in my barn in a regular 3-wire 3-way setup. Then add the house switch that is connecting to the barn via a 2 conductor cable? I bet i could do it with a relay or something like that - but not sure if there is a clean way to make this happen without ripping up the old 2 wire from house to barn. Appreciate the help!

This may be a long post, but thanks for any help you guys can offer! I am installing a 240V garage heater that will be hardwired. I already have 220V wiring/circuit on the same wall that was for an old hot tub no longer here but need to extend the wiring up higher on the wall to be able to reach the heater. Here are my questions.. #1. The heater is 5000W with a max amp of 20.9 (21). Does that mean it should be on a 30amp breaker? #2. Wiring should be 10 gauge correct? #3. - How do I know if I need 10/2 or 10/3? I attached a wiring diagram from the instructions if that helps. [img]https://cimg9.ibsrv.net/gimg/www.doityourselft.com-vbulletin/959x839/screenshot_20210122_191653_onedrive_feab7044ecefa68a8727394226f67ced213b065f.jpg[/img] 4. Most confusing part for me (photo attached).. The current breakers in my box listed for the hot tub are spots #25 AND #27 ("Hot tub" is written across both spots on the panel door). One is a 20A and one is a 15A. Do I pull both breakers out and replace with a 2 pole 30 amp breaker filing in those same two spots? [img]https://cimg9.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x2000/20210122_181219_3cde5b9ee1bb24128540cdbaa33db20cd62810d2.jpg[/img] Thanks for any help!