How to locate buried cables in New Zealand
Finding buried cables is challenging - but with the right resources and tools, you can do it accurately. Here’s the five-step approach we recommend.
Whether you’re planning construction or landscaping at home, locating underground utilities first is essential. Strikes are expensive, slow, and sometimes fatal. Here are the five steps we recommend, end to end.
The five steps
Perform an online search
Start with what's available online. Many councils publish their three-waters and consenting GIS overlays on public portals. UtilityFinder helps you find every operator that serves your area and links to any public records they've published - treat anything you find online as a starting point only, never a substitute for contacting the operator.
Notify utility providers
Online data is never the full picture. Contact every NUO you know of in the area. They’ll provide their best records and any site-specific guidance.
Services like beforeUdig batch the notification across many operators, but membership isn’t universal - research the area and contact non-members yourself.
Identify surface features
After the desktop search, walk the site. Manhole covers, utility poles, transformer boxes, marker tape and warning flags all signal what’s nearby.
Look for surface scarring or discolouration - patched lines and backfill seams trace the trench someone dug to install the asset. Treat anything irregular as a clue, not a coincidence.
Conduct a non-invasive search
Non-invasive detection uses ground-penetrating radar (GPR) and electromagnetic locators (EML). Both methods need trained operators - hire a professional locator unless you’ve been formally trained.
Conduct an invasive search
Where non-invasive methods leave doubt, verify physically. Hand potholing or hydro excavation exposes the asset without risking it. Hydro excavation is especially useful: pressurised water and a vacuum truck remove soil precisely without damaging cables.
Get permission from the operator and council first. Use safe excavation practice and PPE. Document depth and position when you find the asset - that record feeds the next project.
GPR vs EML - which does what
Both tools earn their fee. Knowing the difference helps you brief the locator, read their report and understand the gaps.
Electromagnetic locator
Detects the field around energised conductors or signals injected into traceable infrastructure. Fast, portable, and the workhorse of most locates.
- Excellent on metallic conductors and tracer wires
- Quick sweep coverage; cheap to mobilise
- Blind to plastic pipes without a tracer
Ground-penetrating radar
Pulses radio waves into the ground and images what reflects back. Non-destructive; gives real-time depth and position for whatever EML can’t see.
- Sees plastic, concrete and unenergised assets
- Direct depth read-out on most kit
- Slower, soil-dependent, harder to interpret
Conclusion
Locating buried cables in NZ combines online research, surface inspection, non-invasive detection and physical verification. Follow all five steps; skipping any of them is where strikes start.
If you’re unsure, hire an independent locator. The fee is a rounding error compared with the cost of a strike, and the risk transfers to someone trained to handle it.
Keep reading
How to safely locate underground utilities
The PAS128-aligned five-step process every NZ project should follow.
Understanding utility markout colours
Once your locator paints the ground, here’s how to read what they’ve drawn.
Finding underground utility data in NZ
Where the records actually live - NUOs, council GIS, beforeUdig, and certified locators.
Find your local power & comms operator
Operator directory by region - request plans before any cable detection.
See what's underground at your address.
UtilityFinder maps NZ utility operators on a single interactive map. Pin your worksite and start your plan search in seconds.