First the power poles.  30 and 35 foot poles are set 6 foot deep.   Add an extra 1/2 foot for every 5 foot of pole above 35 foot.  My preference around the farm is underground.  All it takes is to be involved with one electrical accident on a farm and you will never want overhead around bins and barns ever again.

Rich, dad and I have built "pole sheds" using old utility poles all over his farm.  We set the pole 3 foot deep, 4 foot occasionally on sheds upto a height of 16 foot sidewalls.  Back fill with a little dirt to hold pole and finish backfill with sand and gravel while tapping the pole and occasionally tamping.  After about a month come back and top of the hole from the settleing that occurs as wind vibration settles the sand and gravel.

Sand/gravel pack back tighter than dirt and allow moisture to leach away from the pole for longer life.

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