I need to run a line from my home to an outbuilding about 100 feet away, but 175 feet from panel to panel. I have a deck and walkway between the home and outbuilding that I thought I would just run the line under in conduit rather than burying. I am thinking of a 6-3 line with ground for a 50 amp service, perhaps a couple 1500 watt heaters, some lights and a few outlets. Should I use cable or 4 single wires (all identical??) and do I need to run what I use in conduit in the garage attic and down an outside wall before going under the deck and walkway? Also, what size conduit will I need to use?
If you run conduit you would use individual wires. You could run the entire distance in conduit if you choose.
A 50 amp circuit only requires a #10 ground so you would have 3-#6 and 1-#10 copper wires for this circuit. These would fit in a 3/4" PVC schedule 40 conduit according to the Code.
With a light load (4 KW is less than half of this circuit) voltage drop should not be an issue but if you add a large motor load like a compressor you may get a slight flicker in your lights when the compressor starts. The longer the distance on the circuit the more this becomes an issue. Since you are currently oversized it should not be a problem unless you plan to put a larger load on the end of the line in the future.
Good luck and be careful!