What Are Service Active Links, Neutral Links and Off Peak Load Control Wiring in Sydney?

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What are service active links, neutral links and off peak load control wiring in Sydney? Service active links and service neutral links are the sealed, insulated connection points at your switchboard that join the network's incoming supply to your own installation, and the Service and Installation Rules of NSW set exact construction, mounting and labelling requirements for each. Where you run a controlled, off peak load such as hot water, an extra piece of switching equipment is also required at the metering position.

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1. The service active link

SIRNSW Clause 4.9 sets six requirements for a service active link. It must be the all insulated type, fitted with a cover suitable for sealing, with a separate terminal for each conductor rather than conductors sharing a single clamping point. Its current rating must not be less than the capacity of the incoming conductor, it must be located so it is easily accessible and safe to work on, and it must be identified as a "service active link" in a legible and durable manner consistent with AS/NZS 3000. Where the switchboard uses hinged panel construction, the link may be located on the rear of the panel, a detail worth knowing before assuming every link has to sit in plain view on the front face.

2. The service neutral link

Clause 4.10 sets a near identical list of requirements for the service neutral link, with one key difference in the terminal design: rather than a single terminal per conductor, the neutral link must use a separate tunnel terminal for each conductor, clamped by not less than two screws. It must also be the all insulated type with a sealable cover, carry a current rating not less than the incoming conductor's carrying capacity, and be identified as either a "Service Neutral Link" or "Meter Neutral Link". The mounting height is specific and easy to get wrong on a tightly packed board: not higher than 2.0m and not lower than 0.5m above the ground, floor or platform, with special situations referred back to the distributor.

3. What the neutral link has to accommodate

Clause 4.10.1 then lists exactly what the service neutral link must be able to take: the incoming neutral conductor from the network, the customer's own neutral conductor, a separate neutral connection for each meter or control device on the installation, and the neutral for the off peak contactor coil where one is fitted. On a board with multiple meters or several off peak circuits, this quickly adds up to more terminal positions than a single small link can comfortably provide, which is one reason an older switchboard often needs a genuinely larger neutral link, not just a bigger main switch, when a switchboard upgrade adds metering or controlled load circuits.

4. Off peak load control equipment

Clause 4.10.2 covers the switching gear for a controlled, off peak load, most commonly a hot water system billed on a separate off peak tariff. Where the controlled load exceeds 25 amps on a single phase, the installation needs a sealable, non latching contactor located at the metering position, itself protected by a sealable 10 amp circuit breaker. The non latching requirement matters in practice: it means the load genuinely switches off when the network's load control signal says so, rather than staying engaged through a latch that a customer could defeat. Our guide to what controlled load actually means covers how these tariffs work from the customer's side, including the billing and timing detail that sits alongside this wiring requirement.

5. Why the sealing and labelling rules matter in practice

Every one of these links and the off peak contactor and its circuit breaker has to be sealable, and in practice distributors and metering providers do seal them, since an unsealed link or contactor is an easy point for someone to bypass metering or controlled load billing. For a homeowner this mostly means one thing: if a seal on your neutral link, active link or off peak contactor has been broken, whether through age, a previous unrelated repair or simple wear, it needs to be reported and resealed by an accredited provider rather than left as is, since an unsealed link can also be flagged as a compliance issue during a routine metering visit.

6. A common fault that starts right here

A poorly terminated or undersized neutral link is also one of the more common root causes behind a neutral link running hot, something we cover in detail in our guide to neutral link overheating. Getting the link's current rating and terminal count right the first time, in line with Clause 4.10 and 4.10.1, is a straightforward way to avoid that fault turning up later as an emergency callout.

Why it's Level 2 ASP work

Every link covered here sits at the join between the network's incoming supply and your own installation, which places this work in Level 2 ASP territory. A Level 2 electrician is accredited to install, reseal and certify these links correctly, and to coordinate any off peak load control wiring with your metering provider.

How High Demand Electrical helps

We are a licensed local team, not a call centre, and we size every service active link, neutral link and off peak contactor against the actual load it will carry, not just whatever fits the existing board. Servicing homes and businesses across Sydney's West, South West and Sutherland Shire, we regularly find undersized or incorrectly terminated neutral links during smart meter upgrades and switchboard work, particularly on older boards that have had off peak hot water or extra metering added over the years without the link itself being reassessed. HD Inner West's guide to reducing energy bills with off peak metering covers the billing side of controlled load tariffs that this wiring requirement supports.

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Related reading: what a compliant service protection device requires and controlled load 1 and 2 explained for NSW homes.

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