I have 24 birds, 4 breeds, large egg layers. No roos. I built my coop 8 x 16. I ran in a 3/4" water line, a 20 amp electric line, and a telephone line all in the same trench to the coop, some 220 ft from where power exits my home. I planned to put the gate directlly over the top of the trench so as to have power at the gate as well as the coop. I pulled a loop of the buried housewire up and covered it with a cinder block until I was ready to do the gate, so the power was right there waiting for me when I needed it. I set several 4"x8"x16"cinder blocks for the threshold under the gate to discourage digging under it. While I was at it, I set a plastic single-gand eled box in the cement between the cinder blocks. (I also set a yard hydrant around 12 ft from the coop for water at the site.)
The pen is 185 ft around. I set 6" X 10'creosote poles in cement for the corners to ht of 8 ft, and two where the grade/slope changed too much for the fence to be bent to follow, for a total of 6 poles. Then I pulled a mason's line between each pole and dug a trench 4"x4" continuous. I then used a slammer and set 6 ft steel t-posts to be 5 ft tall, at 10 ft intervals all around, at the very inside edge of the trench, which is very straight. Then I cut and stretched and tacked the fence (2 X 4 galvanized welded wire, 6 ft tall) in place to the wood poles and at the bottom of each steel post, where the bottom of it would be slightly below the top of the trench all the way around. I got my 40 yr old electric cement mixer and using coarse sand 5:1 with portland cement, I mixed and poured the trench level to the top, capturing the very bottom of the fence in it. I wet the trench first to slow the curing of the cement. I finished using a margin trowel. Then I put insulators about a foot apart on every pole that will keep the hot wire away from the fence 2". Then I finished attaching the fence to the steel poles. Very important: I then put a 24" tall course of chicken wire inside of the pen all the way around at ground level. Coons will pull birds thru the 2x4 welded wire a piece at a time, so the chicken wire is a must to keep that from happening. Also you do not want your birds to put their inquisitive heads into your hot wire, especially on a wet day.
Next, I got galvanized 14 ga wire 1/4 mile roll, and streteched it around the entire pen at 4 levels a foot apart. I used 4 large springs that I got at
tractor supply (along with everything else exc the poles). I set the springs in the middle of each run of the hot wire for tensioning purposes and they work very well to keep the hot wires taught. I pre-stretched them on a 2x4 and secured with two nails and pulled the nails our after the hot wire was connected to the springs on each end. I powered it up using a 5 mile (4 kv) fence charger. I made a sheet metal cover that looks like a miniature phone booth cover to keep it dry. It is mounted on the gate-post. An ordinary idoor outlet is up at the very top inside/under the top of the cover I made. I also put an outdoor duplex outlet immediately inside of the gate for whatever might come up later that would call for electricity. I also put two indoor type outlets inside of the coop for later additions, work, changes, etc. I also extended the hot wires to the front of the gate itself and it is hot 24-7 like the pen is. I used a 6 ft copper ground rod to ground the charger, but also grounded it to the fence. That way, if the first contact does not discourage them, they still have 3 or 4 more chances of getting a good jolt as they climb, since the hot wires are only 2" from the fence itself.
I am going to set a catch and release trap outside of pen near woods and bait it with an egg constantly so as to trap and kill any preds in the neighborhood, whether fox, coon, opossum, or skunk (egg-suckers) I have no worries about hawks or owls since my birds are nearly full grown now, plus I have so many crows hereabouts that they will run off any hawks, owls, and any other preds they see on the ground as well. I hear that you can buy some of that synthetic orange or yellow polypropylene twine and criss-cross over an open top pen to discourage hawks. No guarantee that they won't just land there tho. Scarecrow? That is it for what I did. So far, so good. I do shut the two pop doors at night tho just in case. I have indoor guillotine-type doors that I can drop down into place. I use 1/16" stranded steel wire and pulleys overhead above the soffit to operate the doors from the outside.