South Australian Current Regulations South Australian Current RegulationsSchedule 2—Requirements for underground lines and certain other
powerlines
(regulations 49 and 50)
In this Schedule—
listed standards means the standards (both national and international), codes,
guides and other documents listed in the Appendix at the end of this Schedule
as published as referred to in the Appendix or, if no such reference is
included in the Appendix, as published from time to time.
(1) Underground lines
must be designed so that—
(a)
cables have safe levels of electrical insulation; and
(b)
cables will carry load currents for which they are designed without failure;
and
(c)
cables will pass short circuit current which will enable the correct operation
of protective devices; and
(d) the
required clearances between a building or structure and an underground
powerline as prescribed by regulation 82 are maintained,
and so as to comply with the listed standards or achieve, to the satisfaction
of the Technical Regulator, the same or better safety and technical outcomes.
(2) In determining
electrical service conditions and the physical environment under which the
line will operate, due care must be given to the consideration of extremes
that may occur, the likelihood of their occurrence and the associated risks.
Cables and their accessories must, so as to ensure safe operational
performance, conform to the listed standards or achieve, to the satisfaction
of the Technical Regulator, the same or better safety and technical outcomes.
(1) The rating of a
cable must be sufficient to pass the electrical load for which it is designed
without failure or excessive heating.
(2) Rating of cables
must be determined in accordance with the listed standards.
5—Short circuit rating of conductors and cable screens
(1) The cable
conductors and cable screens must be of sufficient size to pass short circuit
currents without overheating for the time taken for the operation of the
protective device.
(2) The short circuit
capacity of cable must be determined in accordance with the listed standards.
Underground lines must be installed in a safe manner in accordance with this
Schedule and the listed standards or so as to achieve, to the satisfaction of
the Technical Regulator, the same or better safety and technical outcomes.
7—Installation of underground lines
(1) An
underground line must be installed in accordance with Table 1 below and,
subject to this clause, at the depth fixed for the designated voltage and
cable type.
(2) For the mechanical
cover and enclosures referred to in Table 1 below, 1 of the
following must be used:
(a) a
layer of concrete at least 50 mm thick with a characteristic strength
defined by AS 3600 and AS 1012 and determined to be not less than
15 MPa at 28 days placed not less than 50 mm and not more than
150 mm above the cable and overlapping the cable by at least 40 mm
on each side; or
(b)
concrete slabs of at least 40 mm thickness with a characteristic strength
defined as AS 3600 and AS 1012 and determined to be not less than
15 MPa at 28 days with—
(i)
each slab touching the next so that there are no spaces
left between slabs; and
(ii)
the slabs being placed not less than 50 mm and not
more than 150 mm above the cable and overlapping the cable by at least
40 mm on each side of the cable; or
(c) a
plastic or composite material that offers comparable protection (depending on
depth of installation).
(3) The enclosure
referred to in the last column of Table 1 must be a medium or heavy
galvanised steel tube conforming to AS 1074 or a non-metallic heavy duty
conduit conforming to AS/NZS 2053 (depending on depth of installation).
(4) If it is
impractical to lay an underground line at a depth which complies with
Table 1 then they may be laid at a lesser depth provided that additional
covers or enclosures are installed to provide equivalent protection to that
prescribed.
(5) The
underground line, from where it enters the ground to a position where it
complies with the requirements of depth and protection in Table 1, must
be protected by a cover or enclosure described above.
(6) Table
TABLE 1: Minimum depth of burial from surface of ground to top of cable or
enclosure
|
Method of burial and burial depth (in metres) | |||
|---|---|---|---|
| |
Direct buried |
Direct buried and covered by mechanical cover |
Enclosed in conduit or pipe |
|
U ≤ 1 kV | | | |
|
Single core type |
(a) For
a single insulated single core type—1; |
0.6 |
0.45 |
| |
(b) For
a double insulated single core type—0.75; | | |
|
Multi core type |
For a double insulated multi core type—0.75 |
0.45 |
0.45 |
|
1 kV < U ≤ 22 kV |
0.75 |
0.6 |
0.6 |
|
22 kV < U ≤ 66 kV |
1 |
0.75 |
0.75 |
8—Part of underground line installed on or above ground
(1) If an
underground line is located on the surface of the ground or attached above the
surface of the ground, it must be mechanically protected to a height of
2.4 m from any surface on which a person can stand to the point where it
enters the ground.
(2) The mechanical
protection must be provided—
(a) by a
cable guard made of mild steel of 2.5 mm thickness for HV cables and
1.6 mm thickness for LV cables, galvanised to AS/NZS 4680,
AS/NZS 4791 or AS/NZS 4792; or
(b) a
galvanised steel tube conforming to AS 1074; or
(c) some
other material giving equivalent mechanical protection.
(3) If the attachment
of the underground line is more than 2.4 m from a surface on which a
person can stand, the cable need not be mechanically protected provided
that—
(a) the
cable is beyond reach (determined in accordance with AS 2067
Appendix G) from windows or other accessible parts of the building; or
(b) the
cable is less than or equal to 1 000 volts; or
(c) the
cable is more than 1 000 volts but is metallic screened; or
(d) the
cable is within a substation.
(4) If the cable is
high voltage, it must be enclosed in metallic piping or casing which is
earthed in accordance with these regulations.
Separation between cables and service lines of other utilities laid parallel
must comply with the listed standards.
(1) Underground lines
must be maintained to be in a safe operating condition.
(2) A system of
maintenance must be instituted for underground lines and their components,
including—
(a)
predetermined processes to confirm the safe state of components;
(b)
managed replacement programs for components approaching the end of their
serviceable life.
(3) Maintenance
programs must be carried out in accordance with the listed standards.
Appendix—Standards, codes, guides and other documents relating to
underground lines
|
In this Appendix— (a) ANSI
means American National Standards Institute; (b) IEC
means International Electrotechnical Commission; (c) IEEE
means Institute of Electrical and Electronic Engineers. | |
|
High voltage cables | |
|
Electric cables - Polymeric insulated - For working voltages
1.9/3.3(3.6) kV up to and including 19/33(36) kV
|
AS/NZS 1429 |
|
Electric cables - Impregnated paper insulated - For working voltages up to and
including 19/33(36) kV |
AS/NZS 1026 |
|
Electric cables - For underground residential distribution systems
|
AS/NZS 4026 |
|
Power cables with extruded insulation and their accessories for rated voltages
from 1 kV up to 30 kV |
IEC 60502 |
|
Power cables with extruded insulation and their accessories for rated voltages
above 30 kV up to 150 kV - Test methods and requirements
|
IEC 60840 |
|
Low voltage cables | |
|
Electric cables - Impregnated paper insulated - For working voltages up to and
including 19/33(36) kV |
AS/NZS 1026 |
|
Conductors in insulated electric cables and flexible cords
|
AS/NZS 1125 |
|
Electric cables - Polymeric insulated - For distribution and service
applications |
AS/NZS 4961 |
|
Electric cables - Polymeric insulated - For working voltages up to and
including 0.6/1(1.2) kV |
AS/NZS 5000 |
|
Electric cables - For underground residential distribution systems
|
AS/NZS 4026 |
|
High voltage cable accessories | |
|
High Voltage Cable Terminations |
ANSI/IEEE 48 |
|
High Voltage Cable Joints |
ANSI/IEEE 404 |
|
Separable insulated connectors for power distribution systems above 1 kV
|
AS 2629 |
|
Continuous cable ratings | |
|
Electric cables - Calculation of the current rating
|
IEC 60287 |
|
Electrical installations - Selection of cables - Cables for alternating
voltages up to and including 0.6/1 kV |
AS/NZS 3008 |
|
Short circuit currents | |
|
Calculation of short circuit currents |
IEC 60949 |
|
Installation | |
|
Services in Streets—A Code for the Placement of Infrastructure Services
in New and Existing Streets (prepared for PUACC and published September 1997) |