On Tue, 19 Nov 2019 21:33:23 -0600, Jim Joyce
wrote:

Hi folks,

I'm planning to run a new electrical circuit out to a storage shed in my
back yard and I'd like some help with the details. I'm the homeowner and
I'll be doing most of the work myself, but I want it to be safe and up to
code.

1. I have called 811 - Call before you dig. They'll be coming out on
Thursday of this week to locate and mark all of the underground utilities.


2. I will be using a licensed electrician to connect the new service to the
existing service, but other than that final step everything else is on me.
I have experience with switches and fixtures, but not with the other
aspects of the project.


3. The rest of the 120VAC circuits in my home are 20A circuits, so by
default I'm planning to make this new circuit 20A as well. I believe a
single 120VAC circuit should be fine for both lights and receptacles out
there. The biggest load I can envision is possibly running a miter saw,
which is rated at 12A. Just in case I take that saw out there, I think a
15A circuit might be stretching it thin.

Q: Any issues with a single new 20A circuit for both lights and
receptacles?


4. Web calculators say I should use 8AWG wire for this circuit because the
run is about 120 feet, from the exterior of the house to the exterior of
the shed. I'm planning to buy 3 solid copper wires, 8AWG, in colors white
(neutral), black (hot), and green (ground). This is instead of a packaged
cable such as Romex because I think it will be less expensive to buy
individual wires and because it might be easier to pull 3 wires through
conduit than to pull Romex.

Q: Any issues so far? I know the black and white wires need to be 8AWG, but
does the green (ground) also need to be 8AWG? Am I looking for wire labeled
THHN or is it something different? I'm buying everything at the local Home
Depot.


5. I'm planning to use conduit versus direct-bury wire. Web calculators
seem to indicate that 1/2 inch conduit is fine, but I was thinking about
using 1 inch to make pulling the wires easier. I'm also open to using 3/4
inch conduit.

Q: Does code mandate a minimum conduit size? (Conduit fill) Does common
sense suggest a different (larger) size? Also, does conduit get assembled
as dry press fit, or does it get glued, section by section?


6. The house has a 240VAC breaker box on the exterior wall, with no room
for an additional breaker, so I'm planning to buy a small 2-circuit
sub-panel that I'd attach to the house, right next to the existing 240VAC
panel. I would ask the electrician to connect the sub-panel to the existing
240VAC panel.

Q: I assume the electrician can create a new circuit from the 240VAC panel.
Are there any issues with that plan?


7. The conduit will be buried by using a trencher. My understanding is that
electrical conduit needs to be buried at least 18 inches deep, whereas if I
went with direct bury I'd have to go 24 inches deep.

Q: Any advice on the use of conduit versus direct bury cable?


***

Once I get power to the shed, I'm good with the project after that. I
appreciate any help I can get with the questions above or anything I might
be overlooking.



Don't let the internet pedantics screw with you too much.
1/2" is probably fine if you run enough wire in there initially (7
legal but maybe not possible). I think 5 is plenty. That gives you
240v capability and an extra switch loop. That will be a tug and use
lube. 3/4th is too damned close in price to be worth the hassle.
8 gauge is just silly. What is your load going to be? A weed eater?
Some other garden tool? It will just run an imperceptible amount
slower .If you had an induction motor load I might worry but don;t get
silly. It is a damned shed. If you think it will be a shop some day
use 1" and use a #12 to pull in your 4ga.