Зображення сторінки

177. Joints.

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.

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

[ocr errors][ocr errors][ocr errors][merged small]

flux; the solder shall be relied on only to give good electrical connection.


An efficient lightning arrester shall belo Hous

placed on the pole, connected to the line and to a permanent ground for every — of conductor.

The mains shall be so proportioned ion"

that the maximum fall of potential between 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 lowpotential system, p. 120, et seq., may be followed 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.)


180. Alternating System.


Street Lighting Circuits—Arc or Incandescent.

oušči. (Note.—The specification for the low cuits potential system, p. 120, et seq., may be followed in general but the following additions and modifications should be in


182. Poles. (Add to sec. 168, p. 121.) Lamp poles shall be not less than —

in length, with tops not less than— in diameter, and set — of their length in the ground.

oo::" (Add to sec. 172, p. 122.) Where there is but a single wire on a pole a bracket may be used instead of a cross-arm. Where necessary break-arms shall be used to carry wires from the line out to the lamp.

184. Steps. (Note.—Steps may be desirable on lamp poles, if so add to sec. 174, p. 123.)

...oft. Lamps shall be suspended at the places

located on the attached map by means of (brackets, mast-arms, cross suspension, etc.) The bottom of the lamp to be not less than — above the roadway.

The lamps and fixtures must be secured against damage or interference through ordinary wind storms, and all wires so connected that there shall be a minimum danger of short-circuiting or grounding.

The following fixtures and appliances

shall be furnished and erected:

water-proof hoods complete with reflectors, sockets, and

bracket | cross-suspension |attachments. goose-neck brackets, – in length

complete with post-socket or flange
and the necessary guy wires.
sleet-proof pulleys.
feet — inch weather-proof rope
for raising and lowering lamps.
double cleats for winding up sur-
plus rope,

186. Fixtures (Incandescent).

feet— inch rope for suspending lamps, -, - c. p. — volt lamps.

[ocr errors]

from the exterior circuit. The “Off” and “On o' positions shall be plainly marked and the switch shall be so constructed that when at the position marked “Off” the wires on the inside shall be entirely cut out of the main

water-proof circuit cut-outs for

outriggers, in length for at-

taching to the exterior of build

outriggers, – in length for at-

taching to poles.

- | * | pole tops.

mast arms, – in length, with

proper arrangement for raising and lowering lamps. Bidders shall submit design of mast-arm recommended. sleet-proof pulleys.

« НазадПродовжити »