MAR. 11.] THE NEW ZEALAND GAZETTE. 835
All switchboard circuits shall be so arranged that the
course of any conductor may be readily identified.
Adequate means of access, free from danger, shall be pro-
vided for every switchboard passage-way; and the following
provisions shall apply to all switchboard working-platforms
and passage-ways, unless the bare conductors, whether over-
head or at the sides of the passage-ways, are otherwise
adequately protected against danger by divisions or screens
or other suitable means :
(a.) Passage-ways constructed for low-tension switchboards
shall have an overhead clearance of 7 ft. between the con-
ductors and the floor, and a clear width measured from bare
conductor of not less than 3 ft.
(b.) Passage - ways constructed for extra high - pressure
switchboards, other than operating desks or panels working
solely at low pressure, shall have an overhead clearance of
not less than 8 ft., and a clear width measured from bare
conductor of not less than 3 ft. 6 in.
(c.) Bare conductors shall not be exposed on both sides of
the switchboard passage-way unless either (l) the clear width
of the passage is, in the case of low pressure, not less than
4 ft. 6 in., and, in the case of extra high pressure, not less
than 8 ft., in each case measured between bare conductors;
or (2) the conductors on one side are so guarded that they
cannot accidentally be touched.
Suitable means, such as rubber mats and gloves, shall be
provided and used when necessary adequately to prevent
danger.
7. Circuit-breakers.
All outgoing feeders and distributors from any power-house
or substation shall be provided with automatic circuit-breakers
or fuses set to open at 100 per cent. excess current over the
rated full load of such feeder or distributor, with a time-limit
not exceeding ten seconds.
8. Fuses.
Every fuse shall be either of such construction or so pro-
tected by a switch that the fusible metal may be readily
renewed without danger.
9. Distribution.
The distribution may be carried out either by underground
or overhead conductors; provided that if at any time it is
deemed by the Minister to be detrimental to the public safety
for the conductors or any particular class of conductors to be
overhead such conductors shall, on receipt of notification to
that effect from the Minister, and within twelve months of
such notification, be laid underground, and all consequent and
necessary alterations made by and at the cost of the said
Council.
10. Overhead Electric Lines.
The diameter of any conductor in any electric line laid or
erected for the supply of electrical energy shall not be less
than 0·104 in. diameter (No. 12 S.W.G. or 7/20 S.W.G.). If
the material of the conductor is aluminium the conductor
shall be stranded.
11. Stresses in Overhead Lines.
The stress in overhead conductors shall not exceed the
following limits : 25,000 lb. per square inch for hard-drawn
copper, 12,500 lb. per square inch for hard-drawn aluminium,
34,000 lb. per square inch for steel, and 22,500 lb. per square
inch for iron in the event of a minimum temperature of
32° Fahr. and a wind-pressure of 18lb. per square foot of
diametral plane occurring simultaneously in the case of lines
erected outside borough and township limits, and 12 lb. per
square foot of diametral plane in the case of lines within
borough or township limits. The span between supports and
the sag shall be determined to conform to the above limiting
stresses.
12. Clearances for Overhead Lines.
Overhead lines at low pressure shall not in any part thereof
be at a less height than 18 ft. from the ground.
Overhead lines at extra high pressure shall not in any part
thereof be at a less height than 23 ft. from the ground.
At road crossings the above minimum heights shall be
increased in each case by 2 ft.
At electric-tramway crossings all electric lines shall be
carried at such a height as to be out of reach of the trolley-
pole of a tram-car when in a vertical position.
No overhead electric lines shall come within 2 ft. of any
other aerial wires or cables, except where it may be permitted
to pass either set of wires between other wires at a pole or
support.
Overhead electric lines shall be so erected as to be inacces-
sible to any person without the use of a ladder or other special
appliance.
The maximum sag shall be computed on the assumption
that the conductor is subject to a temperature of 122° F.
13. Supports for Overhead Line.
Every support for an aerial line shall be of durable material,
and properly strengthened against forces due to wind-pressure,
change of direction of line, and unequal length of span. The
factor of safety of supports carrying electric distribution lines
shall be four in the case of steel, iron, or ferro-concrete, and
five in the case of wood, calculated upon the ultimate strength
of material, assuming the wind-pressure to be 20 lb. per square
foot upon a plane surface and 12 lb. per square foot upon a
diametral plane upon a cylindrical surface.
All aerial wires shall be attached to suitable insulators
carried on cross-arms or brackets of suitable material and
cross-section, and they shall be so attached to the insulators
or guarded that they cannot fall away from the supports.
Conductors covered with insulating material shall be so
attached that their insulation shall not be impaired where
they are secured to the insulators.
Electric lines at low pressure may be carried on brackets
attached to buildings; provided they are inaccessible from
any window, balcony, parapet, or other portion of the
building without the use of a ladder or other special
appliance.
14. Maximum Length of Span.
The distance between supports carring electric distribution
lines shall not exceed 150 ft. where the direction of the line is
straight, or 120 ft. where the direction is curved or where the
wires make a horizontal angle at the point of support.
15. Angle of crossing Thoroughfares.
Where an aerial line crosses a street the angle between the
line and the direction of the street at the place of crossing
shall not be less than 60°, and the span shall be as short as
possible.
16. Covering of Overhead Lines.
Electric lines at low pressure shall be insulated throughout
with triple braiding, thoroughly impregnated with water-
proof compound; provided that where circumstances permit
the lines may, with the consent of the Minister, be bare.
Electric lines at extra high pressure shall be bare.
Earthed neutral or intermediate conductors may in all
cases be bare.
17. Low and Extra High Pressure Lines on same Poles.
Low-pressure and extra high-pressure lines shall not be
carried on the same poles or supports except with the consent
of the Minister, who shall prescribe the conditions under
which the electric lines shall be erected.
18. Location of Overhead Lines.
Except by permission of the Minister of Telegraphs, or
subject to an agreement between the Post and Telegraph
Department and the said Council, all overhead electric-
lines shall be placed on the opposite side of the street
to that on which any telegraph lines exist; and where the
errection of the electric-line necessitates the alteration of
any existing lines, and such alteration is approved by the
Minister of Telegraphs, the expense of the alteration shall be
borne by the said Council.
In running the lines authorized by a license through the
street where no telegraph line exists, the said Council shall
keep to one side of the street, and in running wires to the
opposite side of the street the said Council shall arrange so as
to interfere as little as possible with the route on that side of
any future telegraph line.
19. Facility for Service Connections, &c.
Where electric distribution lines are on one side of the street
and telegraph lines on the other, and service is required to be
given from either to the other side of the street, the said
Council and the Minister of Telegraphs shall give to each other
reasonable facilities as far as possible to effect supply. The
Minister of Telegraphs and the said Council shall in special
circumstances give to each other reasonable facilities for the
joint use of poles.
20. Use of Telegraph Department's Poles.
Electric lines shall not under any circumstances be attached
to the Post and Telegraph Department’s poles without the
consent of the Minister of Telegraphs.
Where electric lines are permitted to be supported on
telegraph poles all details of the supports and the insulation
shall be approved by the Minister of Telegraphs, apart from
any other provision contained in these regulations, who may
require such electric lines at any time to be removed from
such telegraph poles on reasonable notice, and without any
compensation whatsoever.
21. Protection of Telegraph Wires, &c.
The said Council shall take all reasonable precautions in
constructing, laying down, and placing the electric lines and