The Rules That Govern Underground Supply in NSW

Putting a service underground looks like a trenching exercise and is not. Four separate layers of requirement apply to it, they come from different places, and the distributor has the final say on the part that touches its network.

This is a plain explainer of what actually governs the work, aimed at a property owner deciding whether to do it.

The four layers

1. The NSW Service and Installation Rules. These govern how an installation connects to the distribution network in NSW. They are legal requirements rather than guidance, and they cover the connection arrangement, the point of supply, the service protection, metering position and the responsibilities on each side of the boundary. Every connection, disconnection and metering job is done to them.

2. AS/NZS 3000:2018, the Wiring Rules. The standard governing the installation itself, including how buried cable is selected, installed, protected and tested.

3. Your distributor's own requirements. Ausgrid and Endeavour Energy each publish their own connection requirements on top of the above, and they are not identical. Same job, different network, different application and different details. This is why the first question on any connection job is which network the address is actually on, and why boundaries running through a single street matter.

4. Everything that is not electrical. Council approval where the work affects a footpath, verge, driveway or a tree. Dial before you dig for other services. Heritage or conservation controls where equipment position and visibility are constrained. Traffic control where a trench crosses a footpath or road.

That fourth layer is routinely the one that delays a job, and it is the one nobody budgets for.

Who is allowed to do it

Work on the service line between the distribution network and your property is Level 2 work. It requires an accredited Level 2 ASP, and specifically one accredited in the relevant class; 2B covers underground service work, and metering sits under 2D.

That is not a commercial preference, it is the legal position. A licensed electrician can work up to the boundary. Past it, an unaccredited person cannot lawfully do the work and the distributor will not approve the connection.

The trenching itself does not have to be done by an electrician. Excavation is excavation, and on larger jobs it is often a separate trade. What must be done by the accredited provider is the cable installation, the connection, the testing and the certification.

The physical requirements, in general terms

Specific figures depend on your distributor's requirements, the installation method, the cable type and where the run goes, which is exactly why this gets designed rather than assumed. In general terms:

Depth. Buried cable has a minimum cover, and it increases where the run passes under a driveway or a trafficable area. Cover is measured to the top of the cable or conduit, not to the trench floor.

Mechanical protection. Conduit, and in some positions additional protection above the cable. Under a driveway, heavier-walled conduit.

Marking. Orange marker tape above the run, at a specified height above the cable, so the next person with a shovel gets a warning before they reach it.

Separation from other services. Minimum clearances from water, gas, sewer and communications, both where a service runs parallel and where it crosses.

Bending radius. Cable has a minimum bend radius and exceeding it damages the insulation in a way that does not show up immediately. This is one of the more common causes of a fault appearing in a new installation months later.

Cable selection. Rated for direct burial or for the conduit it sits in, and sized for the calculated maximum demand with voltage drop over the run taken into account. A long run can need a larger cable than the load alone suggests.

Pits and terminations. Where joints or pits are required they have to be accessible and correctly rated, because a pit that fills with water is the origin of a good proportion of the intermittent faults that turn up later.

The sequence a job actually runs in

1. Assessment and design. The route, the cable, the connection point, the metering position and the maximum demand.
2. Application to the distributor. With its own lead time, which does not compress.
3. Other approvals. Council for verge, footpath or driveway works. Dial before you dig. Traffic control if required.
4. Excavation and conduit. Including any boring under a driveway or under established landscaping.
5. Cable installation. With the bend radius, separation and marker tape done properly rather than quickly.
6. Outage, disconnection, connection. The part only the ASP can do.
7. Testing. Insulation resistance, continuity, polarity, earthing.
8. Reinstatement. Trench, surfaces, turf, paving.
9. Certification. A CCEW issued by the licensed person who did the work, lodged within 7 days of the compliance test, online only through the Building Commission NSW eCert portal from 1 July 2026. Plus a NOSW, a Notification of Service Work, from the ASP to the distributor. Two documents.

What actually drives the cost

Not the cable. The ground and the surfaces.

• The length of the run, and whether it crosses a driveway, paving or established garden
• The ground itself. Sandstone means cutting rather than digging, and across a lot of Sydney that is the single biggest variable
• Whether the route can be bored rather than open-trenched
• Reinstatement of whatever the trench went through
• Whether a point of attachment and overhead span are being removed as part of it
• Whether metering is changing position
• Council and traffic control requirements on the verge
• The distributor's requirements for your specific connection

This is why a quote for underground work given without a site visit is not a quote. The cable is a minor line item.

When it is worth doing

Converting an existing overhead service underground is a real improvement in specific situations rather than a general upgrade:

• The span crosses trees, and the vegetation is a recurring problem
• The point of attachment or the fascia it is fixed to is failing
• A renovation or extension conflicts with the span or its clearances
• The frontage matters, on a heritage property or for appearance
• The ground is already open for landscaping, a driveway or other services, which is when the marginal cost is lowest

That last one is the important one. Doing it while the ground is open is dramatically cheaper than doing it on its own.

Frequently asked questions

Can I dig the trench myself to save money? Sometimes, and on some jobs the provider will agree to it, but it has to be to the specified depth, route and separation, and it has to be open and inspected before cable goes in. Getting it wrong means digging it again. The saving is real but smaller than people expect once the requirements are met.

Is underground supply better than overhead? It is less exposed to wind, trees and storms, and it takes the span and the attachment off the building. It is not maintenance-free. It fails less often and is harder and more expensive to find and fix when it does. That is the trade, and it is a genuine trade rather than a straight upgrade.

Does the whole street have to convert for me to do it? No. Converting your own service from the network's connection point to your building is an individual job. Undergrounding the network mains in the street is a different and much larger proposition, and that one is the distributor's.

How long does the process take? The physical work is often a day or two. The application, approvals and outage booking are what set the calendar, and planning in weeks rather than days is realistic.

Who owns the underground cable once it is in? Generally the property owner, from the connection point onward. That makes its condition, repair and replacement the owner's responsibility rather than the distributor's, which is worth knowing before rather than after.

What if there is rock? Then the method changes and so does the price. Across much of Sydney sandstone is close to the surface, and the honest version of a quote establishes that before the number rather than after.

Getting a real assessment

If you are thinking about converting a service, or putting in a new underground supply for a build, the useful first step is somebody looking at the route and the ground.

Call 0485 824 714. We are accredited Level 2 ASPs under the NSW Government's ASP Scheme, authorised to work on the distribution network, with 15 years on connection-side work and a Lifetime Labour Warranty on what we do. Free quotes, across Sydney and the Blue Mountains on both the Ausgrid and Endeavour Energy networks.