Spotted while driving through the English countryside, not far from Stow-on-the-Wold, on the way to Broadway. I count 21 segments; that would make these bad boys about 10 feet long! The spark gap must be 8 feet or so; gotta be around a half million volts.

Much later: See: http://www.parliament.uk/documents/post/pn163.pdf

In the UK, high voltage transmission is at 275 KV or 400 KV. Which might this be? Hard to tell. My rule of thumb was 15KV per insulator plus one.

To test this theory locally, I think a common transmission voltage in Com Ed territory is 69KV for large industrial sites with their own substations. Abbott has two separate feeds into their subs, and they have 5 disks in each string.

So if that's the case, and if I correctly counted 21 disks in the string, that would mean (21-1) x 15KV = 300KV. So this is probably a 275KV transmission line.

Then, in August of 2011, Dave Dahle suggested that a better estimate would be 12KV per 10" disk. That would work out to 12KV x 21 = 252KV, which is much closer to 275KV than to 400KV.

Let's call this 275KV.