N.Y. Comp. Codes R. & Regs. tit. 16, § 217.2 – (Second District) Stenciling and numbering poles and structures for carrying overhead wire.

(a) Each and every electrical corporation, municipality, telephone corporation, telegraph corporation, railroad corporation, and street railroad corporation owning poles, towers, or frames, hereinafter termed structures, in streets, highways, or public places, or on private rights of way, for supporting and carrying overhead electric wire system for the transmission or distribution of electric energy for light, heat, or power, or for the operation of electric cars or trains, or for telephoning or telegraphing, or for supporting electric lamps or fixtures, shall on or before January 1, 1913, stencil each such structure, except as hereinafter provided, as follows: to wit,
1. (1) with the initials of its name, abbreviation of its name, corporate symbol, or other distinguishing mark by which the owner of each such structure readily and definitely may be determined;
2. (2) with a number by which the location of each such structure may be described.
(b) The manner of making such stencils shall be preferably with paint, otherwise with metal tags, badges, or stamps as each such corporation may elect to use; and that the characters of the stencil shall be of such size and so spaced and hereafter maintained as to be easily read from the surface of the ground at a distance of six feet from the structure.
(c) In the case of two or more companies jointly owning any such structure, the distinguishing mark of each company shall be placed on such structure but not more than one number necessarily shall be placed thereon.
(d) In the case of such structures carrying or supporting overhead trolley wires where there is a double line of structures, one on each side of the railroad track, such stencil need be affixed to but one line of such structures.
(e) In the case of such structures erected upon private rights of way or on the public highways, of such character that the construction may be deemed to be a through or trunk line, such stencil need be affixed only to every fifth structure; provided however that each and every such structure situate within the limits of any city, village, or hamlet shall be stenciled, except as otherwise provided in subdivision (d) herein. Where every fifth structure is stenciled, the commission suggests that the number of the mile from the starting point of the construction be placed on the structure stenciled, and also the number of every fifth structure within that mile. And the commission further suggests that all such structures situate within the limits of every city, village, and hamlet shall be numbered consecutively along each street, avenue, or highway for the distance upon which structures are located.
(f) The requirements herein shall apply to all existing and future constructed structures and to all changes in the ownership of structures.
(g) Every such corporation shall file with this commission on or before May 1, 1912, a statement showing:
1. (1) the initials, abbreviation of name, corporate symbol, or other distinguishing mark intended to be used;
2. (2) the means of stenciling to be employed: to wit, paint, metal tags, badges, or stamps;
3. (3) the method intended to be followed in numbering structures: to wit, within the limits of cities, villages, and hamlets; and upon through or trunk lines.
  Note:
  The above section 217.2 was originally promulgated as Case No. 2499 (Second District).