I'm running a circuit out to our shed/chicken coop. We live in New Hampshire. The electrical demand won't be high, so one 15 amp circuit will be sufficient. We currently have 3/4" schedule 40 buried 12" deep. Long story short, we tried to get it all 18" deep but the work wasn't done properly and about half ended up 12". I'd prefer not to have to redig it, but that is an option if we absolutely had to.
I know that at 12" deep I have this limitation:
"It has GFCI protection before it enters the ground, is limited to 120 volts, and is protected by no more than a 20-amp fuse or breaker."
Which our circuit totally fits, but . . . I did some calculations for the voltage drop, and the recommendation is that I use 8 gauge wire. I am planning on having electronics at the coop (camera, smart light bulb), so i do want "good" electricity.
Trouble is, not only does that add a lot of cost, I'm not entirely sure how voltage drop "works". Do I only have to have 8 gauge for the longest part of the run? Only at the beginning? Fine to run 14 gauge after the connection to the shed?
Plus, the complication of a 12" deep trench makes it hard for me to understand how to combine the requirement for GFCI and 8 gauge wire.
I've made a diagram of what I've got to work with. I could move the GFCI at the exit of the house onto this circuit and use that to my advantage.
My specific questions are on the diagram and I'd love to be directed/corrected on how voltage drop works and what the larger gauge is doing to prevent it.
Update: The most I'll possibly need at the shed/coop is 650 watts. However, I use my shop vac or circular saw at the existing GFCI location.