I did one out front of here some years ago..
Overkill I know but we dug down 4 feet and "tapered" the hole (wider at the top).
Brought the RNC in the side of the pole,
( 10' of painted 2 1/2" EMT) set it in the hole and filled with concrete. Done.. Finished the pipework and pulled in conductors the next day and that was it.. It hasnt moved in 5 years so I doubt it ever will. Trick was the "taper" of the post hole, when the ground freezes and pushes in on the concrete its going to try and push the base down into the earth, not up and out.
A.D
