The record-union., 1894-05-26
NEW DANGER FROM ELEC-
TRICKY.

y
destructive of them, and renders an en-
tire system of pipes dangerous. since
nothing is stronger than its weakest part.
The evil does not appear to come from
the alternate lighting plants. The expert
employed by Omaha reports that the cur
rent generated by dynamos at the power
house
IS distributed to the trolley lines, carried
down the trolley arm to the car motors,
where it does its work, then escapes by the
wheels TO the rails by which il is expected to
return 10 the generator. This would be the
case II the rails presented the best home con-
ductor, for electricity will always follow the
path OF least resistance. But The rails Ofter so
much resistance al the joints that the current
naturally passes through the damp earth 10
the water, gas or cable pipes in the vicinity,
and runs along these good metallic conduct
ors until the rails again present an easier re-
turn To the home station. Where II leaves
the pipes 10 pass back TO the rails the current
keeps eating away the pipes, carrying away
with il these minute particles of metal. In
short time little holes mark the places where
the electricity escapes. These grow larger
and corrole the pipe
The fact of the rapid corrosion of our under
ground iron and lead pipes along the route of
our electric trolley cars is undenlable. In
proof I refer to the ends OF broken pipes in
the Office OF our honorable Board OF Public
Works. That electricity is jumping the rails
to water and gas pipes and back TO the track
was abundantiy evidenced by the volt and
ampeFe tests made by party OF competent
electricians, to which the writer was kindly
invited on Friday last, May 11th.
AT the Nicholas-street poWer-hOuse the diff
ference OF potential OF the water pipe over the
rails where they entered the station was from
three and one-half volts 10 six volts, and the
quantity going TO waste thirty amperes, max
ing No. : wire so hot that ii could not be
helG in the hand and driving q oneeighth
horsepower motor attached TO the water
plug. At the CustOm-house, on Sixteenth
and Dodge streets, enough current Is leaving
the cable-car rails Tor the water pipes OF the
moist foundation to corrode them before the
building will be finished and to fire the neigh
boring buildings. Even on Capitol HILL near
the college, where the ground is dry, q cur
rent from IOur to nine amperes, at voltage
of from one and three-fourths to three and
one-half. works its way from the terminal rail
to the water plug.
In some instances of pipe corrosion spot
of greater or less extent is singled out by the
current and weakened until it becomes de-
tached like chip. These electrolyZed no.
dulles are extremely light Four samples ex-
anined by me gave specific gravity OF 2.36,
400, 1.SS and 1.64, Tie latter resembling
coke III weight and appearance. Bearing in
mind that the SPECIFIC gravity OF caSt1ron is
700 we may naturally inquire what has be-
come of the iron and what changes have
taken place?
The expert then at great length ex-
plains how electrolysis goes on until but
a shell is left Of service pipes, while the
earth near the pipes has gained in iron
what the pipes have lost. In places the
change left a composition resembling
graphite, light, unctuous to the touch. in
combustible and of grayish- black metal
lie luster and marking as easily as lead
pencil.
AS to remedy, reversal of the current
is thought to be sufficient if it is feas-
ible. Insulation of the underground
pipes is declared impracticable. But
the engineers remedy is to keep the
current in the rails by welding the ends
together along the whole line, and this,
he says, Is now being done in Brooklyn.
The next best method is to band the
rails securely to each other with one-inch
copper wire, and a cramp band of like
thickness should connect the two lines of
rails every hundred feet, whenever the
earth is sufficiently moist to render es-
cape of the current to the pipes probable.
In addition, heavy metallic connection
between the return rail and back to the
generators is necessary.
II besides, in the danger district, the rails
are connected at frequent intervals with all
pipes and cables along the track there is every
reason to expect an abeyance OF the evil.
NNTG Il T~a.aE 1C
nouneed successful. As we cannot however,
force the current TO take one path exclusively
when ottle lers are open to 1t, and as one one
hundredth OF a volt difference in potential
between the pipes ana the damp earth sur
rounding them has been found sufficient to
induce eIectrolysiS, would suggest that ire
quent voltage measurements should be made
all over the Ilne even after plan mas been
adopted, and that such changes in return
conductors be made as the measurements may
indicate.
The Omaha authorities have, by re-
quest, communicated with the Mayor of
San Francisco on this subject and trans
nitted the reports of progress of exam
ination and examples of pipes eaten
away by electrolysis.
From all which it is to be inferred that
an electric railway, if properly con-
strueted, is not a menace to water and
gas pipes, but where escape of the cur
rent IS permitted into the earth there is
grave liability to serious damage to un-
derground water and gas eonduits.
The matter is of such importance as to
suggest to the authorities of every city
and town where electric railways are
operated the necessity for investigation
to ascertain if there is imperfect con-
struction, and if the water and gas pipes
are undergoing disintegration by elec-
trolysis, as proved to be the case ia
Omaha.