Unidentified types
Contents
Various British pylon types are presently unidentified. Those that can be properly represented with a photograph or a diagram are listed here. Items only accessible via Street View are not included, as no pages link to Street View so long as Google maintain incomprehensible URLs.
All diagrams on this page are to scale at 12 pixels per metre.
33 and 66 kV
- Some other unknown SL type
- Gloag Type 13, 66 kV, Welland:
Marshall 66 kV
Per [Marshall], this was the standard 66 kV type in 1933. This is almost certainly an Eve tower suite. J L Eve C333 (ca. 1936) appears to be a considerably larger version of this design.
The D3 tower is drawn with approximately 33 kV insulators, as 66 kV insulators don’t fit into the space assuming standard clearance model (conductor position half-way between the steelwork above and below). The only known towers matching this design (and to which these drawings have been corrected on the assumption that they are the same type) are those forming the 33 kV line between Kettering and Northampton, and examination however shows that 66 kV insulators would fit just fine. This is just a snag with the preliminary insulator depictions in these diagrams.
Nicholls 66 kV
Per [Nicholls], this was the standard 66 kV type by 1945. The design is very similar to NWE SL4 from 1936, but the line tower phase clearances are reduced from 10′–6″ to 8′–6″ while the top crossarm is increased from 4′–0″ to 4′–3″.
No lines are known to use this type, but it’s almost identical to the following:
- Colchester to Coggeshall
- Unidentified location
- Somewhere in Surrey
The above three examples all appear to be the same tower suite, and it’s within reason for the drawings in [Nicholls] to simply be inaccurate.
132 kV
Stafford–Wolverhampton
The 1930s line between Stafford and Wolverhampton uses CE PL1 angle towers in conjunction with a line tower that appears to be a precursor to CE PL3 S2.
Another tower of this type appears on the older line between Stourport substation to Bishops Wood substation. The line is too short to draw accurate conclusions but the pattern appears to be the same.
PL1 crossings
Multiple PL1 lines share the same type of crossing tower:
The basic design accepts double circuit crossarms with a maintenance platform below. Most of the examples discovered instead are single circuit, with the spare side of the top crossarm used to carry the earthwire.
In Dumfries it has been built to around 160 feet tall for the River Nith crossing, just south of Kingholm Quay. The towers are around 730 feet (223 m) apart, a comparatively short span. Two more towers are used for a long span crossing in Plymouth; this span is around 2,226 feet (678 m), over twice the standard span of a 132 kV tower. This span uses triple vibration dampers at each end due to its exceptional length. These towers are closer to 96 feet tall (around 29 m), maybe only 10–15 feet taller than typical standard height for 132 kV.
The towers at Dumfries and Plymouth are used on PL1 single-circuit lines (SS PL1 and SWE PL1 respectively). The same type can be found in Exeter with the missing third crossarm.
The tower adjacent to the Gloucester and Sharpness canal is on an SWE PL1(a)&(b) line. The lowest height extension is subtly different (in terms of bracing) to that used at Exeter.
Another double-circuit example (with work platform) can be found in Skewen, Wales, alongside the Tennant Canal and River Neath. This is also on an SWE PL1 line.
There is a crossing over the River Severn on the SWE PL1(a)&(b) line that leads to Lydney; the two towers appear to be this type, single circuit form with working platforms.
PL16 crossings
Multiple PL16 lines share the same type of crossing tower. This type is considerably slimmer than the “PL1” type. All indications are that these towers are PL1-era; the reason for the narrower profile compared to the “PL1” type is not known. Two such towers existed in Avonmouth prior to their removal; according to National Grid, they had been there since the 1930s, which appears to be borne out by historic aerial photography.
Based on the examples below, it appears that this type remained current into the PL16 era.
Examples, all D2S-type PL16 lines unless otherwise stated:
- Two towers spanning the River Welland east of Fosdyke and Fosdyke Bridge, Lincolnshire; route HW
- Two more towers on the same line, spanning the River Nene south of Sutton Bridge
- Two towers spanning the River Great Ouse north of King’s Lynn, Norfolk
- Four towers (parallel routes PD and PKB) crossing the Swale between mainland Kent and the Isle of Sheppey, near Kingsferry Bridge
- Two towers spanning the River Medina, north of Newport, Isle of Wight
- Two can be seen side-by-side south of Arlingham on (at this location) the north bank of the River Severn; one line is SWE PL1(a)&(b) and the other is 33 kV. These are extra-tall towers with the working platforms fitted. The tower type(s) on the far bank remain unidentified.
- The crossing over the River Usk in Newport (South Wales) uses two extra-tall towers, both fitted with working platforms; the east tower is a D60 carrying a deviation of around 40°. This short line uses a mixture of towers, including PL16, SWE PL1 and L4(m).
- One of the four lines crossing the River Ribble west of Preston, Lancashire.