17-229-202 Me. Code R. § 05
Posts: Wood - Sound, round or square, preferably cedar, hackmatack, spruce, or fir. Preservative treatment with creosote oil or cuprinol is suggested. 4" x 4" minimum (square) or 4" minimum diameter (round).
Metal-Steel pipe or structural section steel either galvanized or base coat painted with red lead or other rust inhibitive paint.
All posts to extend a minimum of 4 feet below ground level and to be set plumb. Recommended post spacing 8' to 12'. End and corner posts to be diagonal braced to nearest adjacent post.
Stringers: Minimum 2 x 4 - Spruce or Fir - Sound and free of excessive or weakening knots, and relatively free from warp or wain, preferably treated with creosote or cuprinol after cutting to length. Solidly spiked to wood posts or bolted to metal posts. Three stringers for 6 or 8 foot height of fence, 4 stringers for 10 or 12 foot height. Over 12 foot height would require a special design.
Steel pipe or structural section stringers may be used. These should be either galvanized or base coat painted with red lead or other rust inhibitive paint.
17-229 C.M.R. ch. 202, § 05