i need to run an eletrical wire from one building to another. both have breaker boxes the first is a 200 amp which will feed a 100amp
If you are underground, the wire needs to be at least 36 deep and covered with a warning tape, and fine sand or topsoil, unless you are in rigid steel conduit. If the wire is going to be in conduit, it still needs to be inspected by the AHJ before you pull the wire and after the whole job is finished. Also you need to buy the proper permits and or you jeopardize the resale value of the property if it is not properly inspected. To pull the wire through the conduit will take at least 2 people, you also need to have the correct type of circuit breaker. It is so much easier, faster and in the long run cheaper to have a qualified professional electrician do the work.
You need an electrician to be honest most work on electrical systems need to be covered with the relevent certification under part p of the building regs otherwise you may have problems with insurance /local authoritys etc
Use Wayne's answer as the basis for a bid as recommended by Barney.
Your problem is not a National Code issue, it is local. (I won't go into the whole union/Democrat construction control thing for Chicagoland) Running on the ceiling is an option of you have room for the conduit radius between the structural ceiling and a lower framed ceiling. I believe EMT is acceptable vs. RMC. You're likely going to have to cut 3' pieces and use a lot of couplings, there are some trade methods that could eliminate a few couplings, but if you are not familiar with these ways it will take more time to learn that to just cut it. Not really any simple way, you can leave some studs out during framing, drill holes for straight pipe in studs adjacent to where the pipe needs to be, then slide the pipe into the studs after install. But I am an electrician, and I would be cutting a bunch of pieces trying to use the joist space and dropping vertical whenever I could. One unfortunate effect of this law is spaces get wired to the minimum requirement, and this encourages the overuse of extension cords.
If running underground, you can spend a lot of money on #4-3w/g direct burial cable or you can install 1'' 1/4 pvc conduit and pull 3 #4 cables and a #6 ground. Install a two pole 100 amp breaker in your 200A panel and back feed the 100A panel off of this breaker. You didn't mention how far the two panels are from each other, but if its under 100 feet #4 wire ought to be fine. If you have any more questions feel free to email me. Oh yeah, I forgot to mention that you can also run it over head if the span is not to large. You can use triplex cable. This is the same cable the utility company uses on service drops to your meter. It is relatively cheap(definetley cheaper than copper) I don't have my code book handy but if I remember right you should be able to use #1 aluminum triplex cable.
