Low Voltage Metering
8.9 Direct Connected Metering
Victorian Service & Installation Rules - 2014 8-17
Sites designed with a determined maximum demand approaching 90A per phase or more, should strongly consider installation of LV CT Metering from the outset, to avoid re-work due to load growth.
8.8.2 Meters - Temperature Limits of Specified Operating Range
Metering Facilities and enclosures shall be designed to ensure the meter is not at any time subjected to temperatures in excess of its specified operating range conditions as defined by table 5, of NMI M6 -1 as published by the National Measurements Institute and in accordance with the National Measurements Act.
Unless otherwise defined by NMI M6-1 this should be interpreted as:
Direct Connected Metering (class 1 or 1.5): -10C to +60C LV CT and HV Connected Metering (class 0.2 or 0.5): -10C to +45C
Appropriate air circulation, ventilation, shading or siting of the metering equipment should be considered in meeting those operating temperature limits.
Where metering is enclosed within the customer’s switchboard, a temperature rise limit (above ambient) of 10ºK is to be used for LV CT and HV Connected meters, and 25ºK is to be used for Direct Connected meters, when installed as “built-in components” within the customers Switchboard. Those temperature rise limits shall be used for meters installed as “built-in components” for the purposes of type tests or extrapolation of partial type tests as described in Table 2, clause 7.3 of AS3439.1-2002, and for the purposes of type tests to AS3439.1-2002 by actual test of temperature rise, or temperature rise assessment by extrapolation under AS60890-2009.
8.9 Direct Connected Metering
8.9.1 Meter Panels
Meter panels supplied in accordance with Clauses 8.3 (Metering Obligations) and 8.4.4 (Metering Panels, Surrounds and Enclosures) shall be arranged and not less than the sizes detailed in Clauses 8.9.3.2, 8.10.1.2 and 8.10.2.9 (Single/Multiple Occupancies) for the relevant size of conductors and the number and type of metering installations.
The Responsible Officer should be consulted for arrangements other than those covered by Tables 8.10-1 and 8.10-2
8.9.2 Meter Panel Heights and Clearances
Unless otherwise approved by the Responsible Officer, direct metered electrical installations shall be arranged to meet the clearances provided in Figure 8.9-A (Meter Panel Heights and Clearances):
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Figure 8.9-A Meter Panel Heights & Minimum Clearances
Any doorways or opening providing access to meter panels must be a minimum of 2m H x 0.6m W.
8.9.3 Meter Wiring
connected to the electrical equipment on the switchboard panel, the conductors shall be provided with sufficient free length to allow the meter panel to be moved into a position to enable work to be carried out; All conductors shall be suitably fixed or otherwise retained in position to avoid undue movement or stress at terminals of electrical equipment when the panel is moved or is fixed in position; and
The conductors must be labelled to indicate line and load, phase colours and the associated neutrals identified; and
The conductors shall be sized to the load they are to carry in accordance with the Wiring Rules.
8.9.3.2 Meter Panel Conductors
Only soft drawn multi strand copper conductors or flexible conductors with suitable ferrules of the following sizes and types shall be provided.
Meter whichever is the greater
1000m
Minimum & Maximum Heights Minimum Clearances Clear Level Area
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Table 8.9-1 Meter Panel Conductor Specifications and Limitations
8.9.3.3 Wiring Arrangements
Typical metering layout and wiring arrangements are shown in Section 8 Figures. Meter wiring diagrams specific to particular network tariffs are available from the relevant Distributor. Refer to each distributor’s website. Details of off peak load control arrangements should be obtained from the Electricity Supplier in accordance with clause 8.2 (Tariffs and Metering Configurations).
The wiring of each metering panel shall:
have the metered and un-metered conductors installed, prepared, connected and arranged to conform with the metering arrangements to suit the tariffs selected by the customer and ready for the installation of the metering equipment;
conform with that shown in the wiring diagram for the relevant electrical installation type;
be identified in accordance with clause 7.5.1.4 (Colours and Double Insulation);
have the sheath removed and a length of single insulated cable between 100mm and 150mm through suitable holes in the correct positions ready for connection to the metering equipment as shown in Section 8 Figures ; and
Conductors Sizes
Load Carrying Conductors ≥ 4mm2 to ≤ 35mm2
Metering Neutral Conductors 4mm2 or 6mm2 and coloured black Meter Register Changeover Switch Wire/s Not required
Soft Drawn Copper Conductors Minimum Number of Strands
≥ 2.5mm2 to ≤ 16mm2 7 strands
≥ 25mm2 to ≤ 35mm2 18 strands
(3) Flexible Cables Required Ferrule Size
25mm2 ≥ 22mm long and ≤ 8mm diameter
≤ 16mm2 cables ≥ 18mm long and ≤ 8mm diameter
(2) Maximum Size of Soft Drawn Copper Conductors and Depth behind panel
Maximum Conductor Size (4) 16mm2 16mm2 35mm2
Minimum Depth behind panel 50mm (1) 75mm 150mm
Footnotes;
(1) This depth can also accomodate no more than four 25mm2 conductors attached to the meter panel.
(2) The maximum sizes specified in this table may not be applicable where the use of flexible conductors are incorporated to ensure adequate flexibility.
(3) Flexible cables used for meter panel wiring shall be provided with end-terminals (boot lace ferrules).
(4) Only to be used where;
Consumer’s mains comprise of 16mm2 soft drawn copper conductors forming a 2 Wire 230 volt Single Phase, single occupancy installation.
4 mm2 permitted for any controlled loads.
Cables located at the rear of the meter panel shall be arranged in accordance with the relevant clause contained in the Wiring Rules to prevent undue stress on the conductors or their terminations.
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be permanently labelled at the rear of the meter panel to indicate the function of the conductor, ie, line/load, hot water, etc for the wiring to be terminated by the meter installer.
The incoming neutral conductor to a neutral link shall be clearly identified as such.
Neutral conductors for each meter and time switch shall be coloured black and originate from a terminal of the neutral link. Looping of neutral conductors between terminals of equipment is not acceptable.
Active conductors may be looped at line terminals of equipment where a separate terminal is provided for this purpose.
Refer to clause 8.4.3.7 for unused meter wiring.
8.9.4 Equipment
Where applicable the customer’s agent shall arrange for the supply, installation and wiring of:
Supply protection devices in accordance with clause 7.3.2.5, 7.4.4.9 or 7.5.3.1;
Occupancy Disconnection Devices in accordance with clause 8.10.2.12;
Neutral and active links; and
And other equipment required by the meter provider.
Meter panel fuses shall be spaced not less than 20mm apart where a maximum demand exceeds 50 Amps per phase, to enable effective dissipation of the heat generated.
Meter wiring links shall:
be of sufficient current carrying capacity equal to or greater than the current to be carried by the link;
have separate terminals for each conductor terminated in the link where practical;
be mounted on the face of the meter panels for single occupancies as shown in metering diagram figures; and
for multiple occupancies, may be mounted on the face of the meter panels or within a sealed section behind the meter panels subject to maintaining the required depth;
be fitted with a removable insulating cover with:
the cover fixing screws secured within the cover when the cover is removed; and
sealing facilities to seal the cover to the link’s base.
Phase identification of active links shall be permanently and indelibly marked.
Single occupancy neutral links shall be:
a minimum rating of 100 Amp and 500 Volt; and
equipped with the terminal for the incoming main neutral conductor clearly identifiable by means of a clamping plate terminal set at an angle for ease of conductor access and termination without accessing the rear of the panel.
Incoming mains or sub main neutral link arrangements shall be such that these conductors can be disconnected conveniently from the front of the meter panel for testing purposes.
Low Voltage Metering
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