Currently outstanding questions about UK electricity pylons:
- What is the difference between PL1 and PL1b? Do any drawings remain in existence for PL1b?
- Some of the tower type designations (e.g. DTU, STX) remain undefined: what do they each mean? Moreover, what is the meaning of DTV 45° (0–5° entry)? What does the 45° indicate if not entry angle? Also, why did National Grid change this to DTU45?
- Is the “Scottish” PL16 DD2 tower confirmed to be DD2S, to correspond with the known D2S designation?
- Are L16, L55 and CEB L132 0.4□″ all the same series under different designation?
- What are the “3-X” L16/L55-derived towers? Are they just a 0.175□″ variant, i.e. J L Eve’s version of PL16? From Piccotts End to Lye Green they are used exclusively, while they have also been sighted as 3-X D2 combined with PL16 deviation towers.
- What are the unidentified towers on the Dunoon–Garelochhead line? They are supposedly PL16, but they are given as a significantly shorter height. The Dunoon 132kV Overhead Line Rebuild Project Alignment Consultation document—that names them as PL16—shows on the cover some more “3-X” L55s, which is strange as all the towers on that line visible on StreetView are the small unidentified series.
- Is there any vague consensus as to the definition of “crossarm”? Is there one crossarm per cable or one per rank? Depending on where you look, it seems that it can be either, so what do the “one-per-rank” folk call the arms on single-circuit towers (that are only on one side of the tower)?
- Was there ever an imperial L4 pre-dating the metric L4(m)? That is to say, does the “m” indicate that L4 was metric from the start, or does it denote a metric adaptation akin to L6(m)?
- Is there any definitive, conclusive information on the “(c)” and “(m)” suffixes, especially with regards to L4(m) versus L6(m)? There seems to be contradiction as to which one denotes nearest metric sizes and which one indicates a redesign, and the exact manner of the redesign.
- Do any drawings exist for the 33 kV and 66 kV towers (Eve, Knursling, Riley and Neate etc)?
- Why does Britain use shorter earthwire peaks (and thus lower earthwire shade) than say Germany?
- What is the advantage of using paired insulator strings? They are common in countries such as Germany, but seldom seen in Britain (mostly commonly on some L6 sections, such as in the Wymondley area).
- What are the double earthwire towers for? Why are they only used for a short distance from the substation?