Download MEW E101 April 2013 (pdf, 280kb) - NSW Public Works

Part 2 - Switchboards and Associated Equipment
Fuses shall be suitable for the fault level of the installation and shall discriminate properly
with other protective equipment. Let-through energy and peak current cut-off shall suit
the protected equipment.
Fault current limiter fuse links shall be held in proprietary holders, and shall be mounted
for withdrawal directly towards the operator. Holders for open blade type fuses shall
have barriers complying with Clause 204.6.1.
Where fuse extraction handles are required, they shall be clipped inside the switchboard
cubicle adjacent to the fuses. Where the fuses are located behind more than one cover,
one handle shall be provided behind each cover.
Fuse links shall clearly state the name of the Australian manufacturer or distributor.
A minimum of three spare fuse links shall be provided for every fuse size included in the
switchboard, with the exception of fuses installed solely for fault current limiting. The
spare fuse links shall be mounted in clips in the spare parts cabinet or space described
in Clause 214, and where more than one size is provided, rating labels shall be fitted.
207.6 Fuse Combination Units
Fuse combination units shall comply with AS 1775 and shall incorporate the following
features:
(a) Be either of the totally enclosed type or constructed such that the fixed live parts of
the switches and fuses are fully and directly shrouded to prevent faults developing
between phases by introduction of a foreign straight metallic object. The
shrouding shall be fully effective throughout the entire movement of the air break
switch.
(b) Switching shall be "independent manual operation".
(c) Rating duty shall be "uninterrupted type".
(d) Derating shall be applied, if appropriate, for units mounted in a compact formation
(eg stacked formation).
(e) Utilisation category shall be in general AC-21 minimum, with AC-23 for motor
loads.
(f) Ability to be padlocked in the open position, if indicated.
(g) Contact position shall be clearly shown both with the cover in place and with the
cover removed. A secondary indication independent of the handle position shall
additionally be provided. Where the fuses are mounted in a withdrawable carriage
which ensures isolation from the supply before access to the fuses is possible,
then the secondary indication may be omitted.
(h) Identification of the contact position shall be clearly marked on the F.C.U. in a
contrasting colour.
207.7 Main Switches
This clause shall apply to main switches on main switchboards and local main switches
on distribution boards.
Main switches shall comply with AS 1775 and shall be suitable for fault-making/loadbreaking
duties. Suitable switches are automatic circuit breakers, fused F.C.U.'s and
fault-making/load-breaking switches.
Non-automatic breakers, F.C.U.'s with solid links, or load-making/load-breaking style
switches are not acceptable unless they have been tested for fault-making/load-breaking
duties to AS 1775.
The following features shall be incorporated:
(a) Type of switching shall be "independent manual operation".
(b) Rated duty shall be "uninterrupted type" for a non-ventilated enclosure.
Page 44
MEW E101