The first garage is 200 ft from an on ground transformer that is 45 ft from my house. I do have a meter on the first garage and therefore power bill is separate from main house.
The breaker box is same size as that on second floor of my house. It has lot of space left in it
I am hoping to run wire to new barn that is 800 feet away using this breaker box
if you have a service entrance at the main garage then you can certainly sub feed the new garage. the easiest way to do that is to:
have a MCB panel in main garage with a sub feed CB feeder to the new garage. (personally i would run 2 pole/ 220) buried per <@[email protected]
> comment and sized per addertooths comments, or any of us can do a voltage drop calculation for you.
voltage drop will be less at 220. so really would use less copper to set a new panel then pull 2 circuits.
i would set the new panel in the new garage with MCB as well.
you can use "direct burial" cable if you like. i would recommend you run a second 1" conduit min. and have pull boxes on both ends. easy to put it in now....
now - there are 1,000 ways the details play out... but here are a few pointers to get you started.
you want the new garage to be on its own ground system. the feeders do not carry ground. (isolated conductor - e.g. plastic pipe) you want (2) 10' ground rods bonded to the panel ground buss, and the ground buss bonded to the panel frame.
you can oversize wire all day long, and i would up it to carry 60amp over the distance. if you every wanted to throw a welder or compressor down there you would be covered...
if you want to be very lean... you could just set breakers in the main garage panel and pull circuits to the new garage. but, the work will be the same, the wire won't cost any less and in the end your painted into a corner.
dont get confused by "panel amps" that just the max amperage that panel is framed to go to - in other words - you can take a 225amp panel and put a 40 amp MCB in it... also, you don't have to get a MCB panel in the new garage, you can "back feed" the panel - what that means is a MLO panel, but the "first" breaker are the feeders going in to energize it. i did this in my garage simply because i couldn't get a MCB panel the weekend i was wiring it up. when your dealing with smaller loads and panel "back feed" is not uncommon at all. you can get a little 12 pos 60amp panel at home depot with breakers for like 40 bux....
you can bury the water and power in the same trench - you just need to have a dimension separation per you local codes. but if your taking water down there, will there be sanitary? or just an exterior hose bib?
feel free to hit me up if you have any questions on the wiring / grounding etc...