Physical installation of earth electrode

surprised that the regs and on-site guide don’t even cover protection needed.

Fair comment. I guess the problem is that earth electrodes can take many and varied forms - a huge amount depends on the ground and the surrounding environment. In the UK the old school approach was simply to bang in a rod leaving a few inches exposed above ground and have an exposed clamp onto that. In some situations that may well still be perfectly acceptable - say it's in a quiet corner unlikely to be damaged or have 'long-wheelbase' 4-footed livestock about. In other situation clamping onto existing structural steelwork offers a better solution, or where soil conditions are poor longer buried tapes or grids (or foundation electrodes) might be needed. Not to mention the need to avoid other buried services. Soil conditions can easily change numbers considerably - e.g. in some areas 2.5m separation might be adequate, in other situations the specification is often closer to 8m. In some parts of the world standard practice is to insulate the upper portion of the rod to reduce step potentials at the surface (but they tend to use 2.4m rods minimum and have soil conditions that allow that). There are so many variables and challenges the designer already has to deal with that it's impossible for the regs to be prescriptive and sill be applicable to a wide range of situations.  Once the designer has sorted out the bigger problems, small details like protecting the connection tend to come out in the wash.

I think there is some guidance in GN 8 and of course BS 7430 (to which BS 7671 refers) goes into a lot of detail.

   - Andy.

Thanks Andy very useful - I still believe there is a need for something in the regs and on- site guide.

Thanks Andy very useful - I still believe there is a need for something in the regs and on- site guide.