Зображення сторінки
PDF

The lights shall be supplied by circuits cSSu°n divided as follows: -, etc.

All circuits shall be controlled by 167c0ntroDLot switches placed (location.)

The pole line shall be composed of 168. Poles

straight, select, shaved poles, sound

and free from shakes, checks or large knots; poles subject to extra strain ^hall be specially selected and of ample strength to bear the strain.

All poles must be set of their i»- setting

and Guying.

length in the ground and solidly tamped,

must measure not less than in

diameter at the top, and the distance from the ground line to the lowest cross-arm shall be not less than . Corner, terminal and other poles subject to extra strain shall be securely guyed wherever possible; where impossible to guy them they shall be set with such rake and to such extra depth that the strain shall not pull them beyond the vertical position, allowance being made for the action of water and frost.

170. Distances. No two consecutive poles shall be set

at a greater distance apart than except by special permission from ,

and all poles carrying heavy feeders or

mains shall be set not more than

apart.

171. painting. (As desired.)

1cros^ainrmsnd Gains shall be carefully cut so that the cross-arms make a snug fit and stand at right angles to the pole.

Cross-arms shall be of , thoroughly

seasoned, sound and free from large

knots; painted ;the vertical distance

between cross-arms shall not be less than

. Double cross-arms must be placed

on terminal poles and corner poles carrying wires larger than j B W^G f'

At all corners making an angle greater than two sets of cross-arms shall be used placed at the proper angle to each other.

Pins shall be of selected , shall fit 17r3- P'?9 and

'Insulators.

closely in the cross-arms and be nailed in place.

Insulators shall be of glass, pattern, and of a size suitable for the wire they are to hold.

All poles on which cut-outs are placed 174- Si*p»shall be stepped.

(Note.—Specify character of soil, as 175. son. loam, sand, etc.; also whether rock, marsh land, quicksands, etc., requiring special work.)

All feeder, main and pressure wires 176- wiring.

shall hP i of bare c°PPer wire: i all sprvshall be j insulated with . f all service wires shall be insulated with -.

All wires shall be so handled as to avoid kinking; wagons, drays, etc., shall not be allowed to drive over them; they shall not be dragged along the ground, over cross-arms or through trees in such a way as to injure the insulation; and shall not be allowed to sag unduly between supports, allowance being made for expansion and contraction with changes of temperature. All necessary and proper precautions shall be taken in passing over, through or near buildings of every description, through trees, crossing other lines, turning corners, etc.

Pressure wires shall be carried from the (switchboard) to each centre of distribution unless such centres are connected by an equalizing main, in which case the pressure wires shall be carried to a point on the equalizing main electrically equidistant from the centres of distribution which it connects.

177. joints. Joints shall be mechanically strong and secure so that no movement of the two ends relatively to each other is possible, and shall be carefully sweat-soldered, the joint being wiped free from any excess of flux; the solder shall be relied on only to give good electrical connection.

An efficient lightning arrester shall be Lightning placed on the pole, connected to the line

and to a permanent ground for every

of conductor.

The mains shall be so proportioned ire-F*Jf$mum that the maximum fall of potential be- Potentlaltween the centre of distribution and any service cut-out, including the loss in any

transforming device, shall not exceed

per cent, under full load.

Alternating Current System. (Note.—The specification for the low- i*>. Alter.

v nating

potential system, p. 120, et seq., may be Sy8temfollowed in general. There should be added a specification for placing converters on poles where so required, and for running secondary mains where a single converter supplies a number of buildings, including the distance that the secondary main must be kept from the primary.)

« НазадПродовжити »