July 12.] THE NEW ZEALAND GAZETTE. 2369

(2) Where climbing-space is provided between lines of different pressure the clearance allowed shall be that provided for the higher pressure.

125. (1) Where medium or any lower pressure electric lines cross over buildings the following minimum vertical clearances, measured at a temperature of 120° F., shall be provided :—
     (a) 7 ft. 6 in. above the highest point of flat roofs and open balconies :
     (b) 2 ft. above the ridge of pitched roofs :
     (c) 6 in. above a veranda-roof.
     (2) Every such wire (other than an earthed neutral or intermediate conductor, or a wire having a clearance of not less than 7 ft. 6 in.) shall be covered.

126. (1) Where high-pressure electric lines cross over buildings they shall have a vertical clearance of not less than 8 ft. above the highest part of the building, immediately under the lines, and a horizontal clearance of not less than 4 ft. between the lines and any part of the building.
     (2) The vertical clearance shall be measured at a temperature of 120° F., and the horizontal clearance shall be measured when the line is at a maximum deflection from the vertical, due to wind-pressure, as specified in subclause (1) of Regulation 108 hereof.
     (3) A conspicuous notice—“ Danger—Live Wires ”— shall be fixed to a part of the building nearest to the lines, where it will be readily seen by any person on the building near the wires, and shall be permanently maintained in a legible condition.
     (4) Where it is not possible to fix such notice in a conspicuous place, then a notice, with the word “ Danger ” in letters not less than 2 in. high, shall be fixed to one of the overhead conductors immediately over the highest part of the building, and the necessary clearance shall be allowed between the building and the bottom part of this notice.

127. Where high or extra-high pressure electric lines cross over buildings with metal sides and roof, the roof shall be effectively bonded to the sides of the building, and such sides shall be effectively earthed to ensure the operation of the protective devices in the event of contact being made between the electric lines and any metal part of the building.

128. If any tree or trees are likely to cause damage to an electric line, such tree or trees, or any part thereof, shall be removed by the licensee if requested by the Inspecting Engineer.

129. Overhead electric lines shall be so erected as to be inaccessible to any person without the use of a ladder or other climbing appliance.

130. For the purpose of computing any clearance for an overhead electric line the maximum sag of any conductor shall be assumed to occur at a temperature of 120° F.

131. Where overhead electric lines cross navigable waterways, such clearances as the Minister directs shall be provided.

SUPPORTS FOR OVERHEAD ELECTRIC LINES.

132. (1) Every support for overhead electric lines shall be so located as to avoid any undue obstruction of pedestrian or vehicular traffic.
     (2) Where any electric line is erected parallel to a wire fence the supports, where practicable, shall be at such a distance from the fence that a vertical line taken from the end of the cross-arm nearest the fence will touch the ground at a distance of not less than 5 ft. from the fence.

133. (1) Every support for overhead electric lines shall be of durable material, and of sufficient strength to withstand forces due to wind-pressure, change of direction of line, and unequal length of span.
     (2) The factor of safety of each support shall be 2 in the case of iron, steel, or ferro-concrete, and 4 in the case of wood, calculated on the crippling-load of the structure.
     (3) In computing the applied moments for the strength of supports a wind-pressure of 30 lb. per square foot of plane surface and 18 lb. per square foot of diametral plane of a cylindrical surface shall be assumed.
     (4) In no case shall the strength of a support in the direction of the overhead line be less than one-quarter the required strength in a direction transverse to the line.
     (5) In the case of lattice steel or compound structures, including “ A ” or “ H ” poles, the wind-pressure on the leeward side members shall be taken as one-half of the wind-pressure on the windward-side members, and the factor of safety shall be calculated on the crippling-load of struts and the elastic limit of tension members.

134. (1) Where cross-arm construction is used and the span exceeds 3 chains, double cross-arms, each fitted with insulators, shall be provided on all angles over 45° for high or any lower pressure electric lines.
     (2) Where lines are subject to ice or snow loading, the cross-arms shall be designed to provide additional strength to withstand the extra loading.

135. (1) In computing the strength of wooden supports, the following working-stresses, based on heart-wood measurement, shall be used :—

Pounds per Square Inch
Ironbark .. .. .. 3,500
Other approved Australian hardwoods 3,000
Puriri .. .. .. 2,500
Maire .. .. .. 2,500
Rata .. .. .. 2,200
Black-beech .. .. 2,000
Matai .. .. .. 2,000
New Zealand blue-gum .. 2,000
Totara .. .. .. 1,500
Silver-pine .. .. 1,500
Macrocapa .. .. 1,500
Larch .. .. .. 1,100
New Zealand cedar .. .. 1,000

(2) The working-stress of any timber not mentioned in the last preceding subclause shall be subject to the approval of the Chief Electrical Engineer of the Public Works Department.
(3) No poles of New-Zealand-grown blue-gum shall be used unless the trees from which it is proposed to cut such poles are approved as suitable for that purpose by an officer of the State Forest Service.

136. Pole-steps shall not be placed at a less height than 9 ft. above ground-level.

137. (1) All overhead electric lines shall be attached to suitable insulators carried on cross-arms or brackets of suitable material and cross-section, and they shall be so attached to the insulators or guarded that they cannot fall away from the supports in case they become detached from the insulator, but will fall on the cross-arm or insulator support. Where the loading on the cross-arm is unbalanced the cross-arm shall be braced or so fixed that it is kept in a permanent position.
     (2) All lines at angles shall be attached to the insulator so that the insulator, and not the binding-wire, takes the strain.
     (3) All high and extra-high pressure electric lines at angles shall be provided with guard-hooks, except—
     (a) In cases where the line in becoming detached from any support will not reduce the clearance, on the consequent span, to less than 14 ft. above the ground-level, or
     (b) When shackle insulators are used, the line is on the inside of the shackle ; or
     (c) When strain or suspension insulators are used in which the electric line is attached to the insulator by means of a clamp of a design approved by the Chief Electrical Engineer of the Public Works Department.
     (4) Guard-hooks need not be earthed.
     (5) Pins for pole-top insulators shall not be screwed into the pole-top, but attached to the side of the pole.
     (6) All overhead electric lines (other than service lines) shall terminate on shackle or strain insulators, or on two pin-type insulators fitted in tandem.

138. Where an uplift occurs at a pole—
     (a) High or extra-high pressure electric lines shall be secured to shackle or other suitable insulators so that they cannot become detached, or they shall be protected by a stirrup fitted over the lines and fastened at both ends to the cross-arm, save that in those cases where such lines, in becoming detached from their supports, will not reduce the standard clearance or otherwise be dangerous the shackles or stirrups may be omitted.
     (b) Medium or any lower pressure electric lines erected on the same poles as other pressures shall be secured to shackle, or other suitable insulators, except in those cases where any such line when detached from its support will not decrease the clearance between it and the lines above by less than one-half the clearances specified in Regulation 121 hereof.

139. The cross-arm carrying high-pressure electric lines which are erected on a pole carrying telegraph-lines shall have a distinctive red marking thereon.

140. (1) Where covered electric lines of any pressure are used they shall be so attached to the insulators that their covering is not impaired thereby.
     (2) Bare binding-wire shall not be used on covered wire unless not less than two layers of compounded weather-proof tape is first wrapped round the outside of the covering of the wire.
     (3) Where marlin is used it shall be not less than three-ply of first quality, tightly wound.

141. Every cross-arm on terminal poles or pull-offs shall be so fixed that the pull on the wires will draw the cross-arm towards the pole, and not away from it.

142. Electric lines at medium or any lower pressure may be carried on brackets attached to buildings, provided they are inaccessible from any portion of the building without