Service To Garage

I was wondering if someone can help me with a few questions. I want to run power, preferably 100 amp, to my garage, 100 feet from the house. My house has a 125 amp service box which is full. The garage is a top a 3 tier terraced yard. There is currently 2 12/2 wires run overhead to the garage on 2 20 amp breakers. I know this isn't right, but thats why I'm here. I have been told all different ways to adress this. My question is: how is the cheapest yet correct way to do this? Example, wire size, direct burial, pvc conduit, any help is greatly appreciated. Also I live in Kansas so I don't know if there are code differences from state to state. thanks again.

 

A 60-amp panel in your garage will be considerably cheaper and less effort than the 100-amp panel. Be sure you really need 100 amps. And if you do, then your 125-amp service is going to need upgrading too. Unless you have a large welder or a kiln, the 60 amps is probably enough.

A 60-amp subpanel is easily done with 6/3 UF-B cable (direct buried without conduit, but protected by conduit when above ground). If you need 100 amps, you're going to need #2 copper wire. Some cities allow #3 or even #4 or sometimes #2 aluminum instead, so check locally to see what they require. You'll also need to remove the two overhead lines, and you'll need at least one grounding rod at your garage. The 6/3 UF-B will need to be buried at least 24 inches deep. If digging that deep is nearly impossible in your area, you can reduce it to 18" by using conduit.

This is just the tip of the iceberg, but I don't want to overwhelm you as you come up to speed on this.

 

I appreciate the information, and by all means, feel free to "overwhelm me " on this. I have been doing a lot of asking and I get so many different answers.
My reasoning for 100 amp is I enjoy comfort in the garage. Heat/ac, wire welder, stereo , air compressor, etc. Is this all possible on 60 amp service? Also is that heavy enough wire to run 100 feet?
Thanks again!