One trench the whole way will be easier to pull cable through. You could make it direct, one straight line, or closer to it than otherwise.
Fences can get blown over, run into, replaced for service, or removed for aesthetic reasons, which will become more of a pain to deal with if you run conduit along the fence. Also its less pleasurable to look at conduit than to not.
Your municipality or county should be able to tell you your local minimum depth for buried cable. It depends on your jurisdiction if you're asking about code as I assume.
I would recommend oversizing the conduit significantly to make pulling easier and allow for easy upgrades in the future. 2" can't be that much more than 1". It will be more durable and it could save a lot of work later on.
You can save costs on grounding by using bare wire, or using metal conduit as your grounding conductor. But I would not bury metal conduit to avoid dealing with corrosion. Even a bare ground conductor inside a plastic conduit is going to fare worse than a sheathed over time.
Paint a white line where you plan to excavate and call your utility locating service out to mark obstacles. The white line or shape will keep them from needing to mark unnecessary things in far off parts of your yard.
Rent a trencher and make the work easy on yourself.
Bury conduit larger than you need, because excavation sucks.
Dig depth is often 2foot minimum for nonmetallic, 6 inch minimum for metallic, but ask your codes department what they will approve.
For wire gaguge, use a calculator like http://wiresizecalculator.net/.
By my estimate you would want 6awg, but maybe the direct patch can cut down distance and let you use smaller.
This sounds good overall, with some exceptions. (Also, I basically just set up something similar very recently).
Physical: Sounds good. 90' isn't too bad, and not something where you should have to worry about more than a couple percentage points voltage drop.
Subpanel: If you are using a 100A subpanel, why swap the breaker for a 60A breaker? I am guessing this panel is fed by a breaker in your main panel so that breaker would be rated to protect whatever wire is run. For example, if you run 2AWG Al, it can be protected by a 100A breaker. You also don't need a main breaker in your shed's panel, but it might be nice for convenience.
Wire: I'm not sure what's available to you or what anything costs where you are, but 2AWG is very large, and a 4 wire cable of 2-2-2-4 would be pretty ridiculously stiff. Why not run 4AWG Cu THHN/THWN, which will be easier to work with, and potentially cost less? I'm also not quite sure what you mean about upgrading to 90A based on a 75°C rating... Even running 2-2-2-4 you can get a full 100A without needing to do anything. See below for more about grounding.
Answers:
- Your wire choice seems fine, but I'm still confused about your breaker choice
- THWN is the insulation that allows wet rating. The NEC also specifies several other cables that are suitable for wet locations, including MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW, XHHW-2, ZW
- Running cable through conduit can be difficult when it's large cable. It really depends on the number of bends, wire gauge, and what equipment you have available
- Colors matter but you can wrap the ends with the appropriate colors to ensure you know which is which
- Check out this question if you haven't already seen it. It has a great answer for what wires you should pull (including an EGC).
Best Answer
Type TC cable is for tray cables it requires a cable tray or raceway.
Smurf tube would be the perfect option inside the home as it is cheap and flexible. Non metallic flex conduit is commonly called smurf tube because it is often blue, but could be other colors orange is usually reserved for fiber but that doesn't stop a user for using it in there home for this.
The cable is wet rated and can be direct buried if rated for direct burial if not it will require conduit for the conditions.
The information can be found in article 336 of the NEC it’s only ~2 pages long so not hard to read up on this type of wire.
When sizing the conduit a single wire or cable is limited to a 53% max fill I did not see tc listed for area so you may need to measure yours and make sure the conduit you use inside the home is large enough. For the cable you are using.