I want to build a garage around 100-150 ft away from my house that has a 200 amp service. What size wire will I need to have a 100 amp sub-panel in my garage. Can it be direct burial or should I run conduit?
Sorry, I'd like to help you but your question is too confusing. The way I read it is, the sub panel main disconnect is near or at the service entrance, which is 50 feet away. That's fine. You want to put in a transfer switch so you can transfer the power from the service to a generator to feed the panel. Nothing wrong with that, so long as you put the transfer switch between the panel disconnect and the panel. Distance does not enter the picture. I hope that helps.
Since you have the equipment to dig the trench-- underground is the way to go -- run 2or 4 PVC -at least 18 deep-- as for the size -- I would run the same size as the conductors feeding the house panel-- should be either #1AWG or 1/0-- check markings on inside of your main panel-- your problem will be can you tap into the house panel-easy-- you should put a disconnect for the garage both in the house and garage-- safety--you may need to get extension terminal blocks for the main panel to tie in the wire for the garage-- check with local electrical wholesaler--not homedepot/lowes-- as for the GFI's if you are running the tools you say you will the GFI's may cause nuisance trips- put GFI on any outdoor receptacle sure-- inside I would say no--don't forget to run telephone and cable TV wire for the WORKING SHED
Direct burial must be 24 or more deep, otherwise conduit is required. That's a lot of ditching, overhead would probably be easier. Be sure to use 'UV rated' insulation on the cable, not indoor stuff. If you really intend to draw 100A., ( I doubt that), and are going over 100' you'd better use 1/0 copper cable. If you're just buying a standard 100A panel for the number of circuits to feed a small workshop, #2 should be OK. Any outlets need GFIs. (You will need to drive a ground rod at the garage and bond it to the panel ground. The garage panel has to have a single main disconnect or C.B. regardless of the breaker protecting the feeder cable. (Feeds to separate buildings are treated as services in this respect.)
In my state, TN, The wire from the box to the ground has to be in conduit. Schedule 80 PVC is required. Once the wire is below ground, you do not need conduit for underground cable unless it is run under concrete or pavement. If you plan to come straight from the Meter box, you will have to have a 400 amp meter, and a 100 amp disconnect at the meter base. I would recommend #8 wire.
