"Usable space" means the space on a pole above the minimum grade level which can be used for the attachment of wires, cables, and associated equipment, and which includes space occupied by the pole owner or owners, and, with respect to any conduit, the term means capacity within a conduit system which is available, or which could, with reasonable effort and expense, be made available, for the purpose of installing wires, cable and associated equipment for telecommunications or cable services, and which includes capacity occupied by the pole owner or owners.
N.H. Admin. Code § En 1302.15