12.1 Point of Supply Definitions

Point of Supply Definitions

Quick Answer: The point of supply (POS) is where the electricity distributor’s network ends and the consumer’s electrical installation begins. Consumers terminals are the terminals at which supply is made available. From those terminals onward — typically via consumer mains to the main switchboard — the installation must comply with AS/NZS 3000 and related standards. Upstream service equipment is governed by the distributor (in Queensland: Energex or Ergon Energy Network).

Why Boundaries Matter on Capstone Papers

The capstone and related licence assessments repeatedly test whether you can read a site sketch and correctly name:

1. Where the network stops.
2. Where the consumer’s installation starts.
3. Which conductors are consumer mains.
4. Where the main switchboard (MSB) and MEN link sit relative to that boundary.

Candidates who blur “service cable”, “consumer mains”, “submains” and “final subcircuits” lose marks even when their cable-size arithmetic is correct. Boundaries drive ownership, isolation responsibility, earthing topology, and which rules apply.

Point of Supply — Working Definition

In Australian low-voltage practice, point of supply means the junction at which the distributor’s supply system is connected to the consumer’s installation. It is a defined location, not a vague “somewhere near the meter”. On drawings and in connection offers it may appear as:

The exact physical arrangement differs between aerial and underground services, pillar connections, and meter-panel layouts, but the exam idea is constant: POS / consumers terminals mark the start of the installation you design, size, earth and test.

Consumers Terminals

Consumers terminals are the terminals provided for the connection of the consumer’s installation to the supply. Practically, you will often take consumer mains from:

• Terminals at a meter enclosure or combined service/meter panel arrangement, or
• A connection point defined in the distributor’s service rules after the service protective device, or
• An arrangement shown on the connection drawing for that site.

What you must not do conceptually is treat the transformer LV bushings or the street pillar bus as “your” terminals unless the documentation says the POS is there. For typical domestic and small commercial work in Queensland, consumers terminals sit at the property’s service/metering arrangement.

Capstone stem pattern

A drawing shows a street pillar, an underground service to a meter box on the house wall, then cables into a garage MSB. Assessors expect:

• POS / consumers terminals identified at the approved connection/metering arrangement (as defined for that sketch).
• Cables from consumers terminals to the MSB named consumer mains.
• Cables from MSB to a shed distribution board named submains.
• Final circuits from each board named final subcircuits.

Mixing those four labels is a classic fail.

Service Equipment Versus Consumer Mains

Keep ownership and design responsibility clear:

Typically distributor / service side (concepts):

• Network LV mains and service line (aerial bundled cable or underground service cable as applicable).
• Service fuse or service protective device.
• Metering equipment and associated seals (subject to metering provider / distributor rules).
• Connection standards published for Energex or Ergon Energy Network areas.

Consumer installation side (your design under AS/NZS 3000):

• Consumer mains from consumers terminals to the main switchboard.
• Main switch(es), busbars, protective devices at the MSB.
• MEN link, main earthing conductor, electrode and bonding.
• Submains, distribution boards, final subcircuits.

You still must understand service equipment enough to isolate safely, recognise seals, and not interfere with distributor assets — but you size and install consumer mains as part of the electrical installation.

Queensland Context — Energex and Ergon

Queensland’s distribution network businesses matter for connection paperwork and service construction details:

• Energex — South East Queensland network area.
• Ergon Energy Network — regional Queensland network area.

Both operate under national frameworks with state connection rules, service standards and metering arrangements. For licence exam purposes you are not expected to recite every published construction drawing, but you are expected to:

• Accept that POS and metering location follow the distributor’s approved arrangement for the site.
• Recognise that consumer mains start at consumers terminals, not “wherever it was convenient to cut the cable”.
• Understand that changing service fuse ratings, meter wiring, or network earthing without authority is outside consumer installation work.

When a question mentions “Energex underground service to a meter panel” or “Ergon aerial service to a house”, use it as context for aerial versus underground consumer-mains routing — not as permission to invent a second MEN link or to call the service cable a submain.

Related Concepts Assessors Bundle with POS

Isolation and the main switch

The main switch at the main switchboard isolates the installation on the consumer side. It does not replace understanding of where the distributor’s service protective device sits. Safe isolation procedures must account for which parts remain live when the main switch is open (meter side / service side can remain energised).

Earthing relative to POS

The installation’s MEN connection is at the main switchboard, not at the street pillar and not at every meter enclosure by default. POS defines where supply enters; MEN defines how neutral and earth are bonded once in the installation. Do not relocate the MEN link to “the POS” unless a specific compliant arrangement in the standards/distributor rules requires a defined exception — the teaching default for MEM-style MEN installations remains: MEN at the MSB.

Maximum demand reference

Consumer mains are sized to the installation’s maximum demand (and then checked for current-carrying capacity, voltage drop and fault performance). Maximum demand is calculated for the installation, referenced to the origin — conceptually tied to what the consumer mains and main switch must carry from the POS arrangement into the MSB.

Drawing Literacy — Mark These Four Zones

Train yourself to annotate every practice sketch:

1. Network / service zone — up to POS / consumers terminals.
2. Consumer mains zone — consumers terminals → MSB.
3. Distribution zone — MSB → distribution boards via submains.
4. Final circuits zone — board → outlets, lights, fixed equipment.

If you can mark those zones without hesitation, Section 12.2–12.4 sizing and MEN separation rules become much easier to apply.

Common Exam Traps

• Calling the underground service cable “consumer mains” when it is still distributor service to the meter/POS.
• Calling consumer mains “submains” because they are large cables.
• Placing the MEN link at the meter box “because that is the POS”.
• Assuming Energex and Ergon use identical physical meter-board layouts on every site — arrangements vary; principles do not.
• Thinking consumers terminals are always outdoors — they are where the approved connection presents supply, which may be in a meter enclosure arrangement shown on the drawing.

Bridge Forward

Section 12.2 sizes and installs consumer mains from POS/consumers terminals to the MSB. Section 12.3 treats submains from the MSB onward. Section 12.4 enforces the critical MEN rule: neutral and protective earth stay separate downstream of the MEN link. Master the boundary vocabulary first — every later calculation hangs on it.