PowerGrid Cable Route Survey for Transmission Projects

What is a PowerGrid cable route survey for?

A PowerGrid cable route survey shows what lies in the ground along the planned corridor for an underground high-voltage cable, before the route is fixed. It gives the designer the position and depth of every crossing service, so trench width, burial depth, joint bays and bores can be planned with safe clearance.

Power Grid Corporation of India Limited, a central public sector company under the Ministry of Power, builds and runs most of India's inter-state transmission network. Most of that network is overhead. Inside large cities and at the entry to crowded substations, overhead corridors are hard to secure, so more links run as underground cables. Those are the routes where a survey earns its fee many times over.

Why do underground EHV routes need more than a quick scan?

Because the corridor is wide, the cable is deep and the margin for error is small. A high-voltage cable circuit needs a trench far wider than a fibre duct, room for joint bays every few hundred metres, and separation from other services for heat and safety. A clash found during excavation can force a redesign of a whole section.

We therefore scan the full corridor width, not a single line. Each pass of the antenna fires radar pulses downward and logs the echo from every buried object, building a picture that helps image the subsurface across the corridor. Close cross-lines catch services crossing at an angle, and longitudinal lines pick up anything running parallel. Where the cable will pass under a road, railway or drain by drilling, we add an L-section to give the designer a depth profile.

• Water pipes and sewer trunk mains, often at depths similar to the planned cable.
• Existing 11 kV, 33 kV and 66 kV distribution cables.
• Telecom ducts and gas pipes in city roads.
• Storm drains, culverts and old foundations.

Soil conditions matter here for two reasons. They decide how deep the radar can see, and they matter to the cable designer, because the ground around a buried power cable has to carry its heat away. Our survey does not measure thermal properties. The radargrams do show where the ground changes, from natural soil to rubble fill or old trench backfill, and the drawing notes each change. Designers often use that note to decide where to test the soil.

What do we look for in and around substations?

The earth mat, cable trenches and every cable entering or leaving the yard. A substation sits on a buried grid of earthing conductors, and new cable entries, foundations or extensions must not damage it. Control and power cables run in trenches and ducts that are often busier than the drawings suggest, especially in older yards that have been extended several times.

Old yard drawings are a common trap. A cable trench shown straight may have been diverted around a later foundation, and a spare duct may have been used without a record. We scan the area of any planned works and a margin around it, then mark the findings over the existing drawing so the differences are plain to see. Where we find a cable that appears on no record, we flag it for the site engineer instead of guessing its purpose.

Gas-insulated substations, common in cities because they save space, pack equipment into buildings with cable cellars and floor slabs. Before cores are cut through those slabs we scan the concrete for reinforcement and embedded conduits; our concrete scanning service covers that step.

Where does fibre come into transmission work?

At the approaches, where overhead ground wire fibre comes down from the towers and runs underground into the control building. PowerGrid's telecom business uses optical ground wire on its transmission towers. That optic fibre still needs short underground runs at substations and at joints with city networks. The scanning is the same as for any fibre route; see the details of OFC route GPR survey for method and output. Our wider telecom operator projects details cover that side of the work.

Cable route survey for transmission work at a glance

Alerting other asset owners is a step of its own before digging begins; Call Before u Dig is the background on this, and how it works in India.

How does the survey fit the design programme?

Ideally it comes before the detailed route is frozen, so the findings shape the design instead of forcing changes later. A practical sequence looks like this:

1. The designer marks one or two candidate corridors on a map.
2. We run a fast scan of both to show which is clearer.
3. On the chosen corridor, we run the full-width scan and L-sections at crossings.
4. Trial pits confirm the most critical crossings.
5. The final drawing goes into the route design and the utility owners' approval files.

What does a transmission cable route survey cost?

Standard scanning costs ₹24 per metre and L-section work ₹32 per metre, with GST extra. The minimum order is ₹50,000 in Delhi NCR and ₹1,00,000 in the rest of India. Whole orders above 100 km get 25% off, above 500 km 40% and above 1,000 km 50%.

For example, a 14 km city cable route surveyed as L-section comes to 14,000 × ₹32 = ₹4,48,000 plus GST. A substation yard needing 1.2 km of scan lines in Delhi NCR works out at ₹28,800, so the ₹50,000 minimum applies. Full GPR survey rates are on the price list.

Has Mezux Touch worked for PowerGrid?

Yes. Power Grid Corporation of India Limited (POWERGRID) has commissioned cable corridor scans from us under its own orders. Company names on this page are used only to describe the type of work; all trademarks belong to their owners. We also survey for the EPC contractors and design consultants who build cable links and substations, with our own crews and company-owned radar systems. Send the corridor map and the cable voltage, or ask for a quotation.

Frequently asked questions

How deep can you detect services along an EHV corridor?

In dry soil, GPR often reads down to about 2–3 m. Wet clay has high electrical conductivity, so deeper services there need trial pits or other methods.

Can you work inside an energised substation?

Yes, under the owner's permit-to-work and safety supervision. We follow the site's rules for clearances and access.

Do you design the cable route?

No. We supply survey data and underground utility mapping; the route and the cable design stay with your designer.

Can you survey the bore under a highway for a cable crossing?

Yes, with an L-section across the highway and both pit areas. See our page on HDD route survey.

Will the scan find the earth mat?

Yes. Buried copper or steel earthing shows clearly in most yards, so we can mark where new foundations should not go.

Written by Saniya Parveen · Technically reviewed by Rahul Rai · Updated 8 November 2026