Are there statistics on the long-term reliability of thermit welding vs clamps for making connections in earth electrodes including connections to earth rods? In the absence of statistics are there (informed) opinions?

Is thermit welding widely used by the DNOs in the UK?

I am also not aware of any statistics. The earthing company that I deal with prefers welding as best practice, especially where we have multiple tapes to join onto the earth rods.

In these instances, the tapes are weleded together along with a fly lead and then the fly lead makes a single connection onto the rod. If the installation is done right you can get an earth testing clamp around the flylead to test the earth rod.

I guess it also depends upon your maintenance regime and the nature of your installation. If you are on an earth mat with buried rods that have no access I would have thought a weld would have been more secure than a bolted joints. All the earth mat joints underground are welded so the earth rods should be as well.

Where access is available to the earth rod then a bolted joint can be inspected, but if that isn't part of your maintenance regime then it might be better to utilise weld joints.

Kind regards

Donald Lane