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

Part 2 - Switchboards and Associated Equipment
Plastic coating material shall achieve a tensile strength of greater than 17 MPa
and have a minimum ultimate elongation of 300%.
Application of air drying plastic coating shall be in accordance with the
manufacturer's recommendations to achieve a thickness of not less than 0.4.
Coating colour shall match the adjoining busbar coating.
204.7 Phase Identification
Busbars shall be identified by minimum 25 wide colour bands neatly and permanently
applied and located at not more than 500 intervals along the active, neutral and earth
busbars with a minimum of one colour band for each busbar piece. Adhesive type
material is not acceptable.
MEN links shall have green-yellow and black bands.
Colours shall be red, white and blue respectively for the phases A, B, and C, black for
neutral and green-yellow for earth.
204.8 Busbar Clearances
Clearance between phases and phase to earth shall be not less than that required by AS
3000. All busbars shall be treated as being bare.
Where busbars are connected to proprietary equipment, clearances less than that
required by AS 3000 are acceptable provided the busbars are insulated.
204.9 Cable Connection Flags
All equipment, having main terminals inadequate for the cable size, shall be fitted with
busbar flags. The size of the flags shall be appropriate for the cable lugs to be
terminated and shall have a current rating of not less than the maximum frame size of
the equipment. Busbar flags shall be suitably supported.
204.10 Neutral and Earth Busbars
The ratio of neutral to active busbars size shall be equal to that of the incoming cable
cores.
Earth busbar cross sectional areas shall be in accordance with AS 3000.
The minimum cross sectional area of the neutral and earth busbars throughout the
switchboard shall be sized in accordance with Appendix C of AS 136 to suit 50% of the
indicated fault level for 100% of the time of duration (eg a fault level of 43 kA for one
second requires a minimum uninsulated busbar of 124mm 2 cross-sectional area).
The metal frames of switchboard cubicles and equipment (eg air break circuit breaker,
FCU's etc) shall be effectively bonded to the earth busbar. To achieve a good metal-tometal
contact, painted surfaces shall be stripped and given a corrosion resistant coating
just prior to bolting to the earth busbar.
204.11 Flexible Busbars Take Offs
Notwithstanding other requirements of this document, the conductors between the rigid
busbars and the supply side of a single functional unit may consist of flexible, insulated
copper woven busbars which are forged to a solid unit at both ends. In any case, comply
with Clause 7.5.5.1.2 of AS/NZS 3439.1:2002.
205 CABLING
205.1 Generally
Interconnecting cables may be used instead of busbars for all ratings and shall comply
with the requirements of this clause.
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MEW E101