St. Paul daily globe. [volume] (Saint Paul, Minn.) 1884-1896, 1886-01-07
UND ERGROUND WIRES.
Aid. COOIey's Report Upon the sys-
tenn Quite Exhaustive.

matter of the proposed underground electric
wire system. The report was ordered
published without reading and referred to
the committee on ordinances.
The following pertinent excerpts are
taken from the report:
THE CONDUIT SYSTEM.
In Chicago, Washington, BROOKLYN New
York and other cities conduits Of various
forms and composed of different material
have been in use for the past few years and
are still being successfully operated; al
though in some instances the style of the con-
Quits has been changed to provide for greater
efficiency of service. The various styles are
as follows: CaSJ-iron pipes, through which
the insulated wires or cables are drawn;
wooden trough, in which the wires or cables
are imbedded in concrete; creosoted wooden
troughs, in which cables or insulated wires
are laid; vitrified stone pipes. and the Dorset
conduit system. All these conduits, except
ing, perhaps, the Dorset system, have APP
parently exhibited defects, due to imperfec-
ton of workmanship or 10 the insufEciency of
their qualities as a suitable protecting or insu-
latng material. The difficulties to be guarded
against are: The admission into the pipes OF
sewer or soil gases, surface or subsoil mois-
ture. mechanical injury and early deteriora-
ton through the agency of rust or rot. And
while many of them still carry wires which,
by reason Of their immediate insulation, are
in comparatively good service, they can
hardly be depended upon for such length of
time as would warrant their construction. for
q service that should be made as near perma-
nent as the present state of electrical science
will permit. The Dorset system of conduits,
q sample of which has been presented 10 the
members of the council, has received consid-
cradle attention at our hands. We have care
fully examined it in all its details in Chicago,
where ii has been in successful operation for
nearly two years, and as the result of such
examination. do not hesitate 10 pronounce ii
nnqualifedly the best conduit system that has
yet been presented. As this conduit is now
laid in Chicago, it is composed of two pipes of
seven holes or ducts each, laid side by side
about two and one-half feet below the sur
face of the street, and furnished with man.
holes about two blocks apart. the insulated
wires or cables are easily drawn or pushed
through the ducts. and when properly laid
requires very little care for maintenance.
One hundred telephone or fifty telegraph
wires can easily be accommodated in each
duct. Wires for electric lights should be
placed at some distance from those used for
lighter currents. although they have been OPP
Grated very near each other The cost of the
Dorsett conduit is about $50 900 per mile, con-
tracts ut that price having been made i'm De-
troit and st. Louis since the construction of
the system in Chicago.
The ordinary cable for cocduit use is
wrapped with a double coil of galvanized
wire. and is at once ready for serVice re-
quirng only trench to receive it, These
cables can be made of any number of wires
for any branch Of the service, and wherever
used have never failed to give perfect salts
faction.
These cables carrying from 20 to 100 wires
may be made for from 81 TO 81 per foot,
ACTUALLY COSTING LESS
than the same number of separately insu-
lated wires. The plan of connecting sep
arating the wires is practically the same in
both systems, and consists of box in which
the wires are laid separately and carried into
another cable or into the offices or residences
of parties using them. The Dorset conduit
system contemplates line of pipes, single or
double. the latter preferred, running along
alternate streets, on as extensive plan as
the service demands. Manholes would be
two blocks apart and service wires cOuldebe |
carried through the area ways or alleys into
any part of the block In Chicago the con-
duits are placed from ten to fifteen feet
from the curb to the street. In Detroit the
ordinance requires that they shall be placed
as near the curb as may be. Skilled labor is
required to lay the pipes and make the con-
nections properly, but owing to the narrow
trench required to be dug, travel would not
be interfered with to any great extent, nor
need street be closed while the work is in
progress. We consider it advisable, if con-
duits are used, to require that they be laid
three feet from the curb, or where the curb
should be, and that only one kind of conduit
be adopted, which will to a great extent pre-
vent any inconvenient tearing up of streets.
A space three feet wide, three feet from the
curb, might be reserved on both sides of all
streets on which it is deemed advisable to
permit them to be laid, in order that electric
light wires may be as far removed from the
others as possible by being placed on the OPP
pOsite side of the street. If preference is
given to cables the same general plan might
be followed, but stricter measures will be
necessary TO prevent operating companies
from obStructing the streets. The New York
and New Jersey Telegraph company is now
placing creosoted troughs in the city of
Brooklyn for the reception of cables and we
have been informed by the superintendent of
the work that the plan is perfectly success
fui, the cables being drawn through
the wooden ducts the same as in the Dor
sett system. The life of the trough used by
them is perhaps 10 years. One objection that
has been urged as against the cable system
is, that if a single extra wire is TO be laid the
trench must be opened for the purpose, but
any company operating number of wires,
with a constantly increasing business, would
provide a cable containing more wires than
required Immediately, as the cost OF main
tanning a cable underground of 100 wires
would be no more than the cost of maintain
ing single wire; it would be practically
nothing after the wires were once in place.
RENTAL OF CONDUIT SPACE.
The charges made by the Dorsett company
for the use of their conduits are $500 per
year per mile of single duct, the company
furnishing their own wires and cables.
As means of comparing this cost with
that of overhead wires, we will state that
fair estimate for all kinds of overhead wire
is So per mile per year for each wire, and
that from so to 100 telegraph or telephone
wires may be placed in each duct. The in
creasing efficiency of the service and the
great saving in fire risks would more than
compensate for the extra costs, if there be
objections to the general plan.
The report then went on to state that it is
but natural that the owners of electrical
wires should oppose any projected system,
and then enumerated the companies that
had successfully adopted the underground
system, and had expressed the satisfaction
that it was economy in the end.
The report then placed the relative cost
as follows:
COST PER MILE
Cable system for rs wires, 81 per foot. ST. $50
Cost of laying per mile on paved streets 500
Man holes and connection boxes. 800. 500
$1,000
Or per foot of cable of % wires, Sl15.
Maintenance per mile per year for each
caDle OF 20 Wires.- ---.--..-.. $500
By the conduit system, per mile. 25-wire
cable, at 70 cents per foot. ... 1850
Maintenance per year per cable. .... 200
Rent per duct per year (half rates) .. ESQ
The difference in cost appears to be in
favor of the conduit system by 81, $40 per
mile. which is about balanced by the
amount of rental. Only that plan should
be adopted which shall furnish a salts
factory system, and with the least cost to
sll parties using the same.
By an ordinance granting the right to lay
underground their respective wires, under
such restrictions as will prevent any I'M
necessary obstructing fof streets, and re-
stricting the space to be occupied as already
ii