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Efficient and Effective

Thor Hammer

Thor Hammer is a new assessment tool that allows our overhead line inspectors to quickly and safely test the condition of wooden poles.

Project-on-a-Page summary

Project data

Start date: 01/06/2019
End date: 08/12/2022
Budget: £1,317,502

Across London, the South and East of England, we own thousands of wooden poles that hold up overhead electrical wires. Over time, they need to be inspected, tested and in some cases replaced. This can be a time-consuming and challenging job for our overhead line inspectors.

So we’re working with SP Energy Networks and Northern Power Grid to use Groundline Engineering’s Thor Hammer machine, which looks similar to a conventional hammer but with an inbuilt digital display and additional cloud-based software. The hammers are designed to help inspectors easily and safely assess wooden polls simply by striking them with the hammer. This offers a huge improvement on our current methods, which sometimes involve removing polls altogether and assessing them off site.

Each project partner is trialling a number of Thor Hammers in several locations. We’re working with the manufacturers to add extra functionality to the tool, and the readings we take will categorise poles into three groups: good, moderately degraded and ‘end of life’. We’ll then remove the polls and asses them in our workshop to make sure the hammers are producing sound results.

Currently, most poles are assessed manually by field staff with a conventional hammer. They strike each pole, listen to the noise, and make an assessment based on the sound that’s made. This project will add cutting-edge technology to that process. The Thor Hammer sends a shock wave up and down our poles, and the reflected seismic wave is received by a geophone – a device which converts movement into an electrical reading. The measured data is uploaded into a cloud-based system, where the condition of the pole is calculated and the results shown on a digital display. This creates a uniform, automated and efficient way of measuring the health of our assets. GPS tagging will also provide confirmation of the locations of our poles, which helps make future inspection easier too.


With test being conducted on three different networks, we’ll be able to compare the data and determine the consistency of the Thor Hammers once staff have been trained to use them.

We’ll learn whether the new hammers can correctly identify problems with poles, helping us to plan better and more efficiently repair our assets.

If successful, we can roll-out the devices across our network and train more teams on how to use them.

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