16.—(1) A generator or distributor shall not use any of their overhead lines (except those in generating stations and substations) which they know do not comply with this Part of these Regulations.
(2) An overhead line shall not be used for the purpose of supply at a nominal voltage greater than 400,000 volts.
17.—(1) Subject to paragraph (3), the height above ground of any overhead line, at the maximum likely temperature of that line, shall not be less than that specified by paragraph (2).
(2) In relation to an overhead line used, or intended to be used, at a voltage specified in column 1 of Schedule 2 the height referred to in paragraph (1) shall be—
(a)at any point where that line is over a road accessible to vehicular traffic, the height specified in column 2 of Schedule 2 as appropriate to that voltage; and
(b)at any other point, the height specified in column 3 of Schedule 2 as appropriate to that voltage.
(3) Paragraph (2) does not apply to any section of an overhead line at a point where it is not over a road accessible to vehicular traffic and which—
(a)is surrounded by insulation; or
(b)is not surrounded by insulation but is at least 4.3 metres above ground and connects equipment mounted on a support to any overhead line; or
(c)is connected with earth.
(4) The height above ground of any wire or cable which is attached to a support carrying any overhead line shall not be less than 5.8 metres at any point where it is over a road accessible to vehicular traffic.
18.—(1) Any part of an overhead line which is not connected with earth and which is not ordinarily accessible shall be supported on insulators or surrounded by insulation.
(2) Any part of an overhead line which is not connected with earth and which is ordinarily accessible shall be—
(a)made dead; or
(b)so insulated that it is protected, so far as is reasonably practicable, against mechanical damage or interference; or
(c)adequately protected to prevent danger.
(3) Any person responsible for erecting a building or structure which will cause any part of an overhead line which is not connected with earth to become ordinarily accessible shall give reasonable notice to the generator or distributor who owns or operates the overhead line of their intention to erect that building or structure.
(4) Any bare conductor not connected with earth, which is part of a low voltage overhead line, shall be situated throughout its length directly above a bare conductor which is connected with earth.
(5) An overhead line shall not, so far as is reasonably practicable, come so close to any building, tree or structure as to cause danger.
(6) In this regulation the expression “ordinarily accessible” means the overhead line could be reached by hand if any scaffolding, ladder or other construction was erected or placed on, in, against or near to a building or structure.
19.—(1) Every support carrying a high voltage overhead line shall, if the circumstances reasonably require, be fitted with devices to prevent, so far as is reasonably practicable, any unauthorised person from reaching a position at which any such line would be a source of danger.
(2) Every support carrying a high voltage overhead line, and every support carrying a low voltage overhead line incorporating bare phase conductors, shall have attached to it sufficient safety signs complying with Schedule 1 of such size and placed in such positions as are necessary to give due warning of such danger as is reasonably foreseeable in the circumstances.
20. Every stay wire which forms part of, or is attached to, any support carrying an overhead line incorporating bare phase conductors (except where the support is a lattice steel structure or other structure entirely of metal and connected to earth) shall be fitted with an insulator no part of which shall be less than 3 metres above ground or above the normal height of any such line attached to that support.
21. A generator or distributor shall, so far as is reasonably practicable, ensure that there is no interference with or interruption of supply caused by an insufficient clearance between any of their overhead lines and a tree or other vegetation.