Underground Power Connection Rules in NSW: Trenches, Conduits and Depths

The Key Numbers

New underground service cables on your property must be installed in conduit maintained at a minimum depth of 500mm along the entire run — and where site conditions make that depth impossible, extra mechanical protection is required instead. The standard minimum conduit for an underground service is 40mm diameter, and marker tape goes in the trench above the conduit so future digging finds warning before cable.

Distance matters too: if the underground service from the street would run longer than 50 metres, the rules require a terminal enclosure, pit or pillar on the property — a common surprise on battle-axe blocks and long driveways.

Generous slack is also built in: cable is coiled in pits and left free at ends so the network can joint and maintain it without re-trenching.

Who Does What — and Who Pays

The distributor owns and maintains the underground service itself, but the customer provides and maintains the conduits and structures on their own land — and the rules make the property owner responsible for the cost of excavating and reinstating their surfaces (driveways, landscaping) if the distributor ever needs access for repairs. Bury it right the first time and that day rarely comes.

The trench on your property is typically dug by you or your contractor to the required depth, while the electrical side — cable hauling, jointing, and the live connection at the street — is Level 2 ASP work.

Converting from Overhead to Underground

The same rules apply when you convert an existing overhead service to underground — a popular upgrade for street appeal, tree-heavy blocks and storm resilience. The conduit route, depth and any pit or pillar are planned first, so the switchover happens with minimal time off supply.

If your block needs a new connection point, pillar or a longer private run, that's all part of the same job scope for a Level 2 ASP.

Plan the Trench Before You Dig

Trenching is the expensive part to get wrong — too shallow, wrong conduit or no pit where one's required means doing it twice. Get the route and specs confirmed before any digging. Call Sydney Power Group on 0466 125 125 or get a quote.