Pylon of the Month

September's Pylon of the Month is one that I've wanted to feature for a long time but until now, I've always been driving when passing by. This time, I was more organised when returning home after visiting friends in Bath and grabbed my chance as a passenger. You can find it when heading North on the A46 just before joining the M4 at junction 18. What has always caught my eye is the squat appearance and the unsual v-shaped arrangment of the insulator strings. These pylons are on the 400 kV line labelled "Melksham-?" on the open infrastructure map which heads west into Wales, with a short branch line to Seabank power station in Bristol. I don't know why these pylons are squat - to reduce visual impact? Because Bristol airport is not that far away? Because there are other things often flying around the area of which I'm unaware? And is the unusual insulator string design a consequence of their lower height or because of some other factor - the fact that there are two cable bundles on each side of the pylon on the lower cross arm? I drive past these two or three times a year so it would make me very happy to have a definitive answer! It would also be great to know if they are unique or if other UK pylons have a similar design¹.

With pylons in the news quite a lot at the moment, it was interesting to read an article in the Guardian, Pylons v property: power line in Scotland caused divisions but did house price fears materialise? about the Beauly-Denny pylon line. You can a bit of background to the controversy that surrounded the building of it in the Guardian article and also in the Pylon of the Month from August 2017 which featured one of the pylons. There is (of course) nuance in the conclusions of a new report but the general conclusion was:

An analysis of property sales since the line began operating in 2015 showed property price trends along its route mirrored those of the wider local authorities and appeared to be influenced by wider macroeconomic factors rather than the appearance of new power lines.

So no need to panic about all the new lines planned as part of the National Grade upgrid. I suspect, however, that won't stop the headlines.

1.    Twitter/X provided answers to all these questions in the days after this article was posted. This month's pylon is an L9 model and a total of fifteen exist in the UK. Six near Bath (of which you can see two in the photo above), two in Withington (in the Cotswolds), two near Filton (Bristol) and two near Sunderland. The remaining three are in Scotland. The design is indeed intended to reduce the visual impact where the line crosses (in the case) the escarpment. The v-shaped insulator strings explanation deserves to be quoted in full: As for the V-shaped insulators, they were first developed by Hydro-Québec in 1962-65 for use on their first 735 kV lines, to reduce conductor sway in wind, so I assume were used for similar reasons on the L9 (Cit. 'Charging Ahead: Hydro-Québec and the Future of Electricity')