The morning news. [volume] (Savannah, Ga.) 1887-1900, 1899-02-19

about 800 duet feet TO the ton. "a duct foot 7
being a hneal fool length of one single
hole or duct thus a multiple section of
six holes or ducts. three feet in length.
would contain eighteen duct feet) Ii is
also made in single duct sections in two
feet lengths. The multiple duct stands
test of eight tons when sup
ported at both ends and the .
weight applied at the ,center. When
laid on the level. no surface pressure has
in any degree affected 1t. which is an es-
sential condition in overcoming heavy
street traffic. This same conduit is being
used very largely to-day throughout the
country. In Baltimore the installation Of
5000 900 duct feet is about to be commenc- 4
ed. one million duct feet is at present be-
ing put in by the Narragansett Electric !
Light Company of Providence. r. l., while
in New Orleans the Edison ana Telegraph
Companies are engaged in the same work
1.-The conduit is laid in trenches varying
from to 8, and feet in depth, accord |
ing to the nature of the excavation and
to the strength of the line; this varies
from to 50 ducts, starting from the pow
er house, the heaviest trench with So ducts
carries the feeders to distributing points
gradually branching out and diminishing
20 ducts, as these points are reached.
Three ducts being the highest line used by
the company in the present work. The
bottom of the trench, after excavation is
finished, is run to grade and 'tamped hard
TO give firm and true foundation for the
concrete bed of four inches, which is to
be placed in it. Wooden forms of size
to accommodate the conduit and its en-
veloping concrete are set up in position,
and the four-inch bed of concrete is then
laid, 'tamped and allowed to knit and
the work of placing the lower tier of con-
duit then commenced. the separate pieces
being jointed together by means of
dowel pin SS-inch in left and
Ss-inch in diameter, the joint
is then wrapped round with a strip
of burIap soaked in a preparation of as
phaltum lending its adhesive and water
proof properties to the joint the final stage
in which is a complete covering of neat
cement, giving an entirely insulated and
absolutely waterproof JOINT
"At all street corners and branching out
points manholes are constructed. These are
| built as means for pulling in the cable
the jointing up OF same and to allow of
the branching Out in different directions
of the conduit system. The manholes vary
in depth.
The cables are installed or pulled
from one manhole to another as follows:
Rods of about 8 inches in length which
screws into one another are pushed
| through the conduit until they show in
| screwed as they come in. In the mean
| time, at the other end a galvanized iron
wire called the drawing in wire has been
| attached, the remaining rods are unscrew-
ed and the wire drawn through. To this
! again is attached a rope which is pulled
! through in the same manner. The cable
reel is then placed in position and pred
so as to spin round on its axle. paying
out the cable an so doing. one end of the
| rope is 'hitched' onto the cable end and
the other 10 a windlass and either with
! the aid of a horse or a gang of men is
| drawn through into position. The process
| is repeated from manhole to manhoe I'll
| the whole system is III position.
Mr.. Wallace, who superntends the cleo
| trical features of the work, said:
THE benefits to be derived from this
change are safety in the use of a low
tension system; better service resulting
from the better regulation possible on the
| low tension system, and the removal Of
! all dangers of interruption of services by
| the wires being paced underground; the
removal of unsightly poles ana wires from
| the streets.
The dow tension distributing system Is
! commonly known as the Edison three wire
system. 1t Is called low tension because
the voltage Is low. II is called Edison
three-wire because it was the system first
| introduced in New York city by Mr. Ed
|
three instead of two wires to carry the
| current
THE work of putting the conduit in
the pipe and Insulating them is done at the
| factory, when the material is made When
delivered on the work they appear as ordi-
nary water or gas pipes, with the copper
wires projecting from each end. These
pipes are Taid in the gTound like ordinary
water pipes.
This system of mains, when laid and
| connected together, form a net work or
mesh the tubes on streets running north
and south intersecting and being connected
with the mains running east and west in
| the lanes
THE feeders are heavy conductors of
copper, protected by an insulating cover
ing of rubber. Over the rubber is a COW
ering of lead to protect the rubber from
mechanical injury and deterioration. These
lead-coated cables are drawn into the terra
Gotta ducts and manholes bull into the
ground to receive them,
1T will be necessary 10 add new appa-
ratus at the station to serve the customary
connected to the underground system, and
this will be purchased and installed ready
for use by the time the outside work is
completed"
| -Childlike.-Ma must be very