I am almost finished wiring my new pole barn in EMT tubing. I've used PVC conduit outdoors extensively, mostly underground, but this was my first time using EMT. It's challenging if you've never done it...but not all that hard to do.
I was dead set on wiring my barn in Romex, but the electrician I had hired to help me pull the service kind of snickered and advised me to use EMT if I wanted to do it right. He gave me a short lesson in bending tubing and lent me a 1/2" and 3/4" tubing bender. He also told me to do the bulk of it in 3/4" over 1/2" or 1" as 3/4 can handle a sufficient number of conductors for any future expansion. 3/4" is also easier to bend. 1/2" tubing is fine if you have one lone box at the end of the run and you don't need the capacity of a larger tube.
I've heard that the "tube is the ground" many times over the years, but my electrician advised me to run a green grounding conductor in the tube sufficient to handle the largest conductor in the tube. He also advised me against shared neutrals and to run a separate neutral for every circuit. The single grounding conductor in the tube, however, is sufficient and is to be shared.
I ended up running 12 gauge thhn wiring almost exclusively. It can handle 20 amps on 110 or 220V. 12 gauge wire is also not that much more expensive than #14. 20 amp outlets tend to be of a heftier construction than most comparable 15 amp outlets and are nice to have for such things as a 110V welder, or a big chop saw. The breakers (GFCI or not) cost exactly the same and the outlets do not cost that much more. You can use 12 gauge for 15 amp circuits as well. I find that it's cheapest to buy on 500' spools. Having one spool of 12 gauge green and two spools each of black and white wire is very handy as you can pull multiple circuits at once. I use colored electrical tape to differentiate the circuits when pulling the wire.
For my stick welder, I used a single 3/4" tube two #6 conductors and a single 10 gauge ground on a 50 amp breaker.
I was advised not exceed 360 degrees in total bend radius in a single run before hitting a junction box....that makes sense as you have to be able to pull the wire through. Also, buy a gadget to debur the ends of your tubing, especially after cutting. Metal burrs can cut the insulation on the wire and cause shorts. A deburring tool for copper pipe will work fine and can be had at any big box hardware store.
+1 on having a plan.
To develop a plan, review the conduit fill tables, bending guides and watch several videos on YouTube. Adapt to your situation accordingly.
http://www.elliottelectric.com/Stat...nces/ElectricalTables/Conduit_Fill_Table.aspx
https://www.kleintools.com/sites/kleintools/files/instructions/Conduit Bender Guide.pdf
I ran 1x lumber up at the top of posts to attach the conduit. I wanted to avoid having the tubing on the 2X6's in the case that I wanted to come back and insulate further in the future. Looking back, I could have also used Unistrut. Either way, it was suitable for what I was trying to accomplish.
Hope this helps.
