Improvements in Manholes for Underground Electric Conduits.
Year: 1890

page_text: Date of Application, 22nd Apr., 1890-Accepted, 5th July, 1890
COMPLETE SPECIFICATION.
Improvements in Manholes for Underground Electric Conduits.
I, JAMES FERGUSON MUNSIE, of 337 Broadway, City of Brooklyn, County of Kings,
State of New York, United States of America, Electrician, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
My invention relates to certain new and useful improvements in "Man-holes for
Underground Electric Conduits ;" and has for its objects, firstly, to avoid explosions
therein by keeping the man-hole chamber practically air and gas tight; secondly, to
maintain said chamber in as dry a condition as possible; thirdly, to make suitable
provision for insuring the safety of the linemen entering the chamber; fourthly, to
minimize or neutralize the injurious influence of induced currents from high tension
wires upon low tension or battery wires passing through the man-hole chamber; and
fifthly, to provide access to the man-hole chamber from the side and through a con-
stantly ventilated shaft or well, furnished with dry air.
In the accompanying drawings:
Figure 1 represents a vertical cross-section, on a plane indicated by the line 1-1
of Figure 2, of a man-hole chamber and its accessories, embodying my invention ;
Figure 2 represents a horizontal section of the same on a plane indicated by the
line 2-2 of Figure 2;
Figure 3 represents an enlarged detail sectional view of the duct or tube frame
shown in Figure 1; and
Figure 4 represents a detail face view of the door or cover over the entrance to the
man-hole.
Similar numerals of reference indicate similar parts throughout the several views
of the drawing.
The man-hole chambers will be located, in the usual manner, at the intersection of
cross-lines of underground conduits, or at distributing and feeding points along said
conduits, and will consist of two or more compartments, as 5, 6, located one above the
other, and accessible only through an auxiliary shaft or well, 7, the tops of both com-
partments being entirely closed.
The main walls of the compartments, 5, 6, are of brick or stone masonry, so as to
insure solidity of structure, and are provided with an insulating partition, 8, built
into said masonry, and consisting preferably of wooden beams that have been
impregnated, by immersion or otherwise, with boiled olive or other suitable oil.
The upper compartment, 5, serves for the passage of the low tension or battery
wires supplying telegraphic or telephonic circuits and the like; and through the
lower compartment, 6, I prefer to pass the wires carrying currents high in tension
and quantity from dynamos supplying electric lamps, &c.
In order to thoroughly insulate the two compartments 5 and 6, from each other,
I separate them by an insulating floor resting upon and supported by the beams, 8,
and consisting preferably of oil-impregnated boards, 9, 10, separated by an inter-
vening filling, 11, of tar-yarn, Chatterton compound, or the like.
Each compartment is furthermore provided with an independent insulating lining, 12,
separated from the walls of the compartment by an intervening space, which I
prefer to fill with an insulating waterproof and airproof packing, 13, preferably of
Chatterton compound.
By this arrangement of parts, the compariments will be thoroughly insulated from
cach other so that no currents may be carried by conduction from one to the other,
and each will be completely protected against access of air, gas, or moisture from the
surrounding earth.
The tendency of the surrounding earth, especially during cold weather, is to

page_text: condense moisture from the air within the man-hole chamber, said condensations
gathering upon the inner walls and making them to a certain extent conductors of
electricity. To absorb such moisture, as formed, and prevent its deposit upon the
compartment walls, 1 provide in each compartment, a pot or the like, 14, containing
unslaked lime, which will take up the moisture thereby keeping the walls dry and
preserving their insulating qualities.
In connection with the features of my invention thus far described, I wish to call
attention to the following considerations --My object in surrounding the compart-
ment walls with an air-proof and waterproof filling is to protect the man-hole from
all access of moisture and explosive gases from without. The said filling is completely
adapted to such purpose. On the other hand it is, when used alone, of some disad-
vantage, for the reason that it prevents the grounding of currents accidentally arising
within the man-hole. Thus, during the manipulation of wires within the man-hole,
it may happen that the uncovered ends of wires connected to the generator might
come in contact with the said filling and if such surface is moist, the current will
give a shock to the lineman should he inadvertently touch the moist surface. It
Becomes, therefore, of the highest importance to keep the walls of the man-hole as dry
as possible, and also to secure the best possible insulation within the waterproof and
air-proof filling, so that the walls shall be at all times of practically no conducting
capacity. To the attainment of these ends, I have therefore provided the compartments
with the inner supplemental insulating lining, and have taken the necessary pre-
cautions of preventing the formation of moisture upon said lining, by the introduction
of unslaked lime within the compartment; these several provisions cooperating to
produce a man-hole chamber that the lineman can enter with security.
In order to give access to the compartments, 5, 6, I provide in each a side opening,
leading to the shaft, 7, and having a door or cover, 15, adapted to fit closely so as
to hermetically seal the opening.
To this end, I surround each opening with a frame, 16, having a recess formed
by the flange, 17, within which recess is placed a gasket or other packing, 18, and
over this gasket is placed the door or cover, 15, which is held in place by bolts, 19,
passing through the door or cover. By drawing up the nuts, 20, on the bolts, 19,
the door or cover will be firmly pressed against the gasket, thereby effecting an air-
tight fit.
I will now describe my preferred manner of passing the wires or cables into and
from the man-hole chambers. At 21, is indicated what I term duct or tube frames,
consisting primarily of a frame which is set into the masonry forming the compart-
ment walls, and is enclosed by the same, as shown more fully in Figures 1 and 3.
The duct 22, for the electric wires or cables, 23, passes into and through the frame 21,
and fits the same closely. In Figure 3 the numeral 24, indicates a tube sheet fitted
in front of the duct 22, and within the frame 21, through and into which the
tubes 25, for the wires or cables pass. The frame 21 may, however, be omitted if
desired, and the tube sheet may be fitted directly against the masonry.
The frame 21, is to be closely fitted within the masonry, and to that end it is
provided, preferably on both sides, with recesses 26, within which is placed a
packing 27, surrounding the duct 22. A plate or cover 28, fits against the
packing 27, and against the side 29, of the frame, being held tightly against the
latter by the bolts or rivets 30, as shown. By this means, the passage of gas or
moisture between the duct 22, the frame 21, is effectually guarded against. The
requisite number of duct or tube frames and their described accessories is to be
placed in each compartment for the accommodation of the separate conduits leading
into and away from said compartments.
In order to reduce the destructive effects of electric currents from atmospheric
causes, such as lightning sbocks, I prefer to place a lightning-arrester 31, in
proximity to the wires, said lightning-arrester being connected to the earth by an
insulated conductor of large carrying capacity, 32, leading to the grounded rod 33.
Or, if preferred, the lightning-arrester may be connected to the duct frame 21, for
the same purpose.

page_text: When battery wires for telegraphic and telephonic circuits pass through a man-
hole chamber in a parallel relationship to and in proximity to wires conveying
currents high in tension and quantity for electric lighting and similar purposes,
induced currents are set up in the battery with wires, which induced currents
interfere with the battery currents and affect the proper working of the instruments.
To neutralize or minimize this action, I interpose between the two sets of wires
a conductor 53, of large carrying-capacity, consisting preferably of a metal plate
located near the top of the lower compartment, 6, and across the entire length of
the man-hole and through the walls of the same. for a sufficient distance to be
completly grounded at each end. A closed parallel circuit, of which the earth
forms the return, is thus interposed between the two sets of wires. This circuit
acts as a protector to the battery wires, and the induced currents that would other-
wise be generated in the battery wires, are set up in said protecting circuit and
dissipated in the earth.
I will now describe my preferred arrangement of well or shaft 7. At the lower
part of said shaft, I prefer to place a pot 34, containing unslaked lime, to absorb
moisture and assist in keeping the shaft dry. I desire to have a thorough circulation
of dry air through the shaft, and to that end, I provide the following: The top of
the shaft is covered by a perforated plate 35, as shown, and a stand pipe 36, leads
to the lower part or bottom of the shaft, said stand-pipe extending upwardly above
the surface of the ground, (preferably near the curb 37) to a height greater than
the plate 35, so as to create an upward draft through said pipe. The upper end
of the pipe is provided with a hood to prevent the access of rain to its interior.
By the arrangement described, air circulates through the shaft, preventing the
accumulation of explosive gases therein and keeping the shaft in proper condition
for the linemen to enter.
In order to prevent rain or drippings that may enter the perforated cover from
reaching the bottom of the shaft, I place within the shaft a suitable removable
partition or water-catch 38, which may be supported upon a bracket or ledge 39,
or in any other suitable way, the partition being preferably belted to the ledge
upon a gasket 54, to make a water-tight joint.
A pipe 40, passes from the water-catch to the sewer to carry away the water that
may collect upon the water-catch. I provide said pipe with a suitable trap 41, to
prevent gas from entering the shaft from the sewer; and I also prefer to place a
clack valve 42, in the pipe for additional protection.
In order that the circulation of air through the shaft may not be impeded by the
water-catch 38, I perforate the same, as at 43, and cover said perforations with
tubes or hollow cones 44, upon which I place caps 45, as shown. By this means,
air is free to pass through the water-catch, while, as the hollow cones or tubes 44,
projects above its surface, water will not pass through the water-catch.
Within the shaft and below the water-catch 38, I locate a shelf 46, entirely
covering the portion of the shaft below it. This shelf is removable, and upon its
upper surface I spread or distribute unslaked limo, as shown. The air entering from
above, through the hollow tubes or cones 44, is deprived of its moisture by contact
with this unslaked lime, and passes in a dry state through the bye-pass 47, to the
bottom portion of the shaft.
Below the removable shelf 46, I secure a ladder 48, whereby the lineman may
readily reach the lower part of the shaft, after first removing the water-catch 38, and
shelf 46.
In order that the air in the compartments 5, 6, may be thoroughly purified before
the men enter the same, I place suitable air taps or air-cocks 49, in the doors or
covers, 15, as shown. Before the men remove the door or cover, they open these
cocks or taps, so that fresh dry air from the shaft may enter the compartments
through one tap and escape through the other. Instead of the taps 49, any other
suitable arrangement for opening and closing the air apertures in the covers may
be employed. After the air in the compartment has been purified, the door or

page_text: cover 15, may be litted off, and the linemen can enter with safety. A constant
circulation of dry fresh air is kept up in the compartment and sbaft while the
linemen are at work, by means of the pipe 36. After the work is completed, the
cover or door 15, is replaced and tightly sealed to prevent air or gas entering
the compartment.
When the men are working in the shaft or compartment, the pipe 36, may be
used as a speaking-tube, by which to communicate with the men without the necessity
of a nearer approach.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is,
1. A man-hole for underground electric conduits, provided with an air-proof and
water-proof jacket, in combination with a moisture-absorbent for preventing
condensations upon the inner walls of said jacket, substantially as described.
2. A man-hole for underground electric conduits, having low-tension or battery
wires passing through its upper portion, and high tension or electric light wires
passing through its lower portion, in combination with a parallel conductor inter-
posed between the two sets of wires to neutralize or minimize the effect of induced
currents, substantially as described.
3. A man-hole for underground electric conduits, consisting of an upper compart-
ment for the reception of low-tension or battery wires, and a lower compartment
for the reception of high-tension or electric light wires, the said compartments
being provided with air-proof and water-proof jackets, and being insulated against
conduction from one to the other, substantially as described.
4. A man-hole for underground electric conduits, in combination with a side shaft
or well having an opening for communication with the man-hole, a cover or door
for said opening, and ventilating devices in said door, substantially as described.
5. A man-hole for underground electric conduits, in combination with conductor-
tubes entering said man-hole, a duct surrounding said tubes, a tube-sheet traversing
said tubes, and an outer frame surrounding said duct, substantially as described.
6. A man-hole for underground electric conduits, in combination with conductor-
tubes entering said man-hole from an adjacent man-hole, and a tube-sheet receiving
said tubes, substantially as described.
7. A man-hole for underground electric conduits, in combination with a tube-
sheet having a recess 26, containing a packing 27, plate 28, and duct 22, surrounded
by the latter, substantially as described.
8. The shaft 7, having perforated cover 35, in combination with the water-catch
within the shaft, said water-catch having ventilating openings, and means,
substantially as described, for carrying away the water from said water-catch,
substantially as described.
9. The shaft 7, having perforated cover 35, in combination with the perforated
water-catch 38, said water-catch having hollow tubes extending above the perforations
in the water-catch, hoods upon said tubes, and means substantially as described, for
carrying water away from said water-catch, substantially as described.
10. The shaft 7, having perforated cover 35, and ledge or bracket 39, in
combination with the water-catch 38, resting on said ledge, a pipe leading from
said water-catch to a sewer, and a trap or seal in said pipe, substantially as
described.
11. The shaft 7, provided with perforated cover 35, in combination with the
ventilating pipe 36, the water-catch 38, within the shaft, means substantially as
described for carrying away the water from said water-catch, the man-hole,
and the door or cover separating said man-hole from said shaft, substantially as
: described.
12. The shaft 7, having perforated cover 35, and ledge 39, in combination
with pipe 36, connecting with the lower end of the shaft, the water-catch. 38,
resting on said ledge, a packing between the water-catch and ledge, and a pipe

page_text: leading from the water-catch to a sewer, said pipe being provided with a trap or
valve, substantially as described.
13. The shaft 7, in combination with the pipe 36, leading from the bottom of
said shaft, the water-catch 38, the shelf 46, below said water-catch, said shelf
containing unslaked lime, and the bye-pass 47, substantially as described.
Dated this 22nd day of April 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.