UK electricity pylon series
Contents
Overview
This page provides a visual overview of most of the major UK electricity pylon (transmission tower) types found within the UK; it can be thought of as a kind of “Spotter’s Guide to British Electricity Pylons”. The images are all to scale at 12 pixels per metre. Links are provided to the individual series pages that contain more information.
Where possible, the drawings below are derived from industry material. However, they are all only approximations, as even industry drawings can be inaccurate and at times outright erroneous, and the basis for crossarm lengths is inconsistent (either to the centre of the conductor attachment point or to the end of the steelwork). In some instances, details such as bracing structure is taken from photographs and Google Street View imagery, and some drawings are entirely new work when no drawings are available. Some corrections have been made for apparent and verifiable errors in drawings, but some of these may be incorrect corrections. The drawings are however accurate enough for identification purposes.
The exact design of each tower type also varies, either due to customisation during construction or subsequent modification. Many heavily-modified towers exist that do not match any standard design, and terminal and junction towers tend to allow for a variety of crossarm configurations.
As power lines are modified and diverted, old towers are removed and new towers added, and the new towers may be of a completely different series. If the towers on a line appear not to all be from the same series, this is quite likely to be the case.
Designations
The series names used on this site are not all official; some have been devised solely for convenience in order to give the tower suite a name within this website. See the guide page for recognition information and more detailed information on tower series designations.
Coverage
Coverage of 132 kV and above is good insofar as indicating which series exist.
Coverage of 33 and 66 kV remains low due to the limited amount of material recovered; it appears that there are over 30 separate 33 and 66 kV tower suites, but at present there is not enough information to draw them all to scale. 33 and 66 kV types are collected together as the schematics tend not to indicate the design voltage and the phase and ground clearances overlap between the two voltages.
See the completeness progress page for more details on progress to date and the material and details still required in order to achieve complete coverage.
Comparisons
See the comparisons page.
Series list
This list is not exhaustive.
The earliest known date for each type does not indicate the date that the first line completed construction or was energised: it simply notes the earliest discovered information for the type.
All tower heights below are given primarily in metric for ease of comparison; the original imperial height is appended in brackets for types that originated under imperial measurements.
Locations in brackets denote where towers are found only as a substitute and not used for complete lines.
Series | Found | Voltage | Height (line tower) | Earliest known date | Designer |
---|---|---|---|---|---|
Milliken L134 | ❌ | 20.3 m (66′–6″) | 1927 | Milliken Brothers | |
CS-PL1 | 132 kV |
20.2 m (66′–3″) (S2) 23.9 m (78′–3″) (D2) |
1928 | Milliken Brothers | |
Milliken E102 | 14.2 m (46′–6″) (S3) | 1929 | Milliken Brothers | ||
Milliken T163 | 18.5 m (60′–9″) (D3) | 1929 | Milliken Brothers and Blaw Knox | ||
SEE PL1a |
|
132 kV |
24.0 m (78′–9″) (D2) 20.3 m (66′–9″) (S2) |
1929 | GEC? |
SEE PL1(b) | 132 kV |
23.5 m (77′–0″) (D2) 19.8 m (65′–0″) (S2) |
1929 | Callender’s | |
SEE SL2 | 33 kV | 1929 | Watshams | ||
NWE PL2 | 132 kV | ? | 1930 | Milliken Brothers | |
Blaw Knox K721 | 66 kV | 1930 | Blaw Knox | ||
SEE SL3 | 33 kV |
48′–9″ (14.9 m) (D3) 42′–9″ (13.0 m) (S3) |
1930 | Watshams | |
Rannoch–Abernethy |
2 × 132 kV 2 × 132 kV + 2 × 33 kV |
ca. 1930 | ? | ||
SS-PL1 | 132 kV |
20.3 m (66′–9″) (SS PL1 S2) 24.2 m (79′–3″) (EE PL1 D2) |
1931 | Milliken Brothers | |
Milliken E177 | 33 kV |
19.2 m (62′–11″) (double circuit) 22.6 m (74′–0″) (quad circuit) |
1932 | Milliken Brothers | |
Belfast four-circuit | 2 × 110 kV + 2 × 33 kV | 1932 | Callender’s | ||
SEE SL4 | ? | 1934 | Watshams | ||
SEE SL8 | 33 kV | ? | ? | Watshams | |
Spey Valley | 132 kV + 33 kV | 24.8 m (81′–4″) | 1936 | Blaw Knox | |
Blaw Knox K1373 |
2 × 66 kV 2 × 66 kV + 1 × 33 kV 2 × 132 kV |
23.5 m (77′–0″) (type A) double-circuit line tower 23.2 m (76′–0″) (type S three-circuit line tower) |
1936 | Blaw Knox | |
NWE SL4 | 1936 | Blaw Knox | |||
CE PL3 | 132 kV | 1936 | Blaw Knox | ||
PL4/WGR | 132 kV | 26.2 m (86′–0″) | 1936 | Blaw Knox | |
J L Eve C333 | 33 kV | 18.1 m (59′–6″) | J L Eve | ||
Abergavenny/Cwmbran | 66 kV | ? | ? | ? | |
Lydney | 132 kV | Blaw Knox? | |||
PL7 | 132 kV | 26.76 m (87′–95⁄8″) | 1938 | Watshams | |
Blaw Knox K5735 | ❌ | 132 kV | 27.4 m (89′–9″) (DD2) | 1940 | Blaw Knox |
PL16 | 132 kV |
26.4 m (86′–9″) (D2) 26.3 m (86′–3″) (D2S) |
1944 | Blaw Knox | |
Blaw Knox K1201 | 132 kV | 22.6 m (74′–3″) | 1947 | Blaw Knox | |
Blaw Knox K1420 | 132 kV | 13.0 m (42′–6″) (S10) | 1947 | Blaw Knox | |
J L Eve 0.4 (L16) | 132 kV | 27.1 m (88′–10″) | J L Eve | ||
J L Eve 0.175 |
|
132 kV | 26.1 m (85′–8″) | J L Eve | |
Blaw Knox K9906 | 66 kV | 19.8 m (65′–0″) | 1947 | Blaw Knox | |
L34 | 275 kV | 25.9 m (85′–0″) | 1950 | Milliken or Blaw Knox | |
L66 |
|
275 kV | 34.3 m (115′–3″) | Blaw Knox | |
L2 | 275 kV/380 kV/400 kV | 41.6 m (136′–6″) | 1952 | Blaw Knox | |
L3 | 275 kV |
36.9 m (121′–0″) (Blaw Knox D) 36.1 m (118′–3½″) (J L Eve D, C673) 38.1 m (125′–0″) (Blaw Knox DS) 38.0 m (124′–9″) (J L Eve D, C864) |
1953 | Blaw Knox, J L Eve | |
J L Eve C772 | 132 kV | 1957 | J L Eve | ||
Inveraray–Taynuilt | 132 kV | 1959 | ? | ||
L6 | 400 kV | ca. 50 m (varies) | 1960 | Balfour Beatty, BICC, Blaw Knox, J L Eve | |
Blaw Knox T1521 | 275 kV | 38.1 m (125′–0″) | 1960 | Blaw Knox | |
Blaw Knox T1648 | 275 kV/380 kV | 44.0 m (144′–3″) | 1961 | Blaw Knox | |
L7 | … |
132 kV | 26.9 m | 1963 | BICC and J L Eve |
L9 |
|
400 kV | 31.7 m (104′–0″) | 1966 | J L Eve |
Blaw Knox T2175 | 275 kV | 38.1 m (125′–0″) | 1967 | Blaw Knox | |
J L Eve C1415 | 132 kV | 22.3 m (73′–3″) | 1970 | J L Eve | |
Quoich–Broadford | 132 kV | ? | |||
L4(m) | 132 kV | 26.1 m | 1975 | Blaw Knox | |
L8 |
|
400 kV, 275 kV |
46.4 m (400 kV) ca. 40 m (275 kV) |
Blaw Knox | |
L12 |
46.5 m (standard height) 35.3 m (low height) |
? | |||
L4(m) 66 | 66 kV | ? | ? | Blaw Knox | |
Coylton–Auchencrosh | 275 kV | 25.2 m | 1992/2001 | Balfour Beatty | |
L13 | 400 kV | 49.95 m | Babcock | ||
SSE400 | 400 kV | 50.5 m | Balfour Beatty | ||
C-IVI-1 |
|
400 kV | 32 m | ESB International |
Dashed outlines for suspension insulators are approximations only, added for clarity.
33 and 66 kV
Milliken L134
L134 is an early secondary line type.
Milliken E102
E102 is an early secondary line type.
Milliken T163
T163 is an early secondary line type.
SEE SL2
SEE SL2 is a 33 kV tower series; currently it is being grouped under SL2 until we know whether these two types differed in any visible way.
Blaw Knox K721
K721 is a 66 kV tower series.
SEE SL3
SEE SL3 is a 33 kV tower series. The type given in Marshall 1933 is included as it seems to be all but identical; this type is used to fill in gaps left by unrecovered SEE SL3 drawings. Only one drawing has been recovered for SEE SL2 (D60/DT) and it is identical to SEE SL2, suggesting that SEE SL2 and SL3 may be indistinguishable. SEE SL2 is covered under SEE SL3 for now.
Milliken E177
E177 is a 33 kV type notable for having quad circuit towers.
SEE SL4
SEE SL4 is presumably a 33 kV tower series. Drawings for the line towers have not been recovered, nor have D30, S60 and ST.
SEE SL8
SEE SL8 is a 33 kV tower series. Only the terminal tower drawing has been recovered so far; these terminal towers can also be seen on other lines either side of undergrounded section of line.
Blaw Knox K1373
K1373 and K4611 “Christmas Tree” towers are a strange type from the mid-1930s. Note that some lines have been upgraded to 132 kV using the existing towers.
Single circuit:
Double circuit, standard types only:
Three-circuit, standard types only:
NWE SL4
NWE SL4 is an SL tower series designed by Milliken Brothers.
J L Eve C333
J L Eve C333 is a 33 kV tower series.
Abergavenny and Cwmbran
Abergavenny/Cwmbran is a 66 kV tower series possibly derived from C333.
Blaw Knox K9906
Blaw Knox K9906 is a 66 kV tower series. Known examples are currently running at 33 kV.
L4(m) 66
L4(m) 66 is an adaptation of L4(m) for 66 kV.
110 kV
Blaw Knox K1641
Blaw Knox K1641 is, if understood correctly, a suite of single-circuit, flat formation lattice towers designed for deviation and termination of wood pole lines.
132 kV
PL1
See:
- CS-PL1
- SS-PL1
- SEE PL1a
- SEE PL1(b)
- PL4 (WGR PL1)
CS-PL1
CS-PL1 (“original Milliken”) was the first Milliken design for the UK. It is known from CS PL1 and SEE PL2.
Single circuit:
Double circuit:
SS-PL1
SS-PL1 (“revised Milliken”) was the second Milliken design for the UK. It was used for most of the original PL1 schemes including SS PL1, EE PL1, SWE PL1 and NWE PL1. Amongst the various differences between SS-PL1 and CS-PL1, the most noticeable is that the peak of line towers contains bracing.
Callenders designed at least one tower type designated SWE PL1(a)&(b); this is an S2 type used in conjunction with Milliken SS-PL1 angle towers.
Single circuit:
Double circuit:
NWE PL2
Of NWE PL2, only details on some of the special tall towers have been recovered. The remainder of the scheme mostly used the same towers as NWE PL1.
PL1(c)
See under SS-PL1.
Rannoch–Abernethy
The so-called “Grampian pylons” appear to be specific to a single line in Scotland.
Double circuit 132 kV:
Double circuit 132 kV plus double circuit 33 kV:
Belfast four-circuit
Callender’s four-circuit type likely specific to Belfast; ca. 1932.
SEE PL1a
SEE PL1a is a slimmer design than the Milliken towers; the designer is taken to be GEC (listed seemingly incorrectly in the Tower Bible as Pirelli). Not to be confused with the unrelated Callender’s type SWE PL1(a)&(b) (see under SS-PL1 above). This type was also used for the Mid-East England region, presumed to be scheme MEE PL1.
SEE PL1(b)
SEE PL1(b) is a Callender’s type. Not to be confused with the unrelated type SWE PL1(a)&(b) (see under SS-PL1 above).
Spey Valley Extension
Tummel–Keith was Blaw Knox contract K1576 for the Spey Valley Extension in Scotland, constructed circa 1936–1939.
Original dual voltage towers:
Uprated 132 kV double circuit towers:
CE PL3
CE PL3 appears to be the short-lived precursor to CE PL4. Very few PL3 drawings have been recovered, and very few PL3 lines ever existed.
PL4/WGR
The PL4 line tower is remarkably similar to that of PL16. The top crossarm of PL4 D2 is roughly the same height as the other crossarms, while PL16’s top crossarm is distinctly taller than the rest.
PL4 is notable for its double earthwire type having an extra crossarm at the top, instead of the combination phase/earth crossarm arrangement of PL7 and PL16.
This design is assumed to have originated with contract CE PL4. This design was subsequently used during World War II for the Wartime Grid Reinforcement (or War Time Grid) schemes, gaining it the name “WGR”.
Lydney
“Lydney” is a temporary designation for the 132 kV towers found at Lydney in Gloucestershire, England. This seems to be a Blaw Knox design based on its similarity to CE PL4.
PL7
PL7 D2 is quite similar to that of L16/L55, again with open crossarms, and the DD2 type could be confused with PL16 DD2.
The 132 kV Watshams suite that appears to have originated as SEE PL7 was also used (at least in part) for: EE PL3; NWE PL6; MEE PL9, PL12 and PL13; SWE PL10 and PL11.
Blaw Knox K5735
Blaw Knox K5735 is a tower type of which very little is known. Allegedly it was used by a PL7 scheme somewhere. It appears to be the precursor of PL16.
PL16
PL16 contains two designs of line tower. The “Scottish” D2S towers bear some resemblance to the PL1 family and PL4. The “Scottish” D2S types appear to be widespread in England, while the SWE D2 type can be found in Scotland!
Classed as PL16 for now:
Blaw Knox K1201
Blaw Knox K1201 is a single-circuit companion suite to PL16 designed for Scotland.
Strengthened towers:
Blaw Knox K1420
Blaw Knox K1420 is a suite of flat formation towers. There is no known line tower. Wood poles are used for intermediates instead.
Associated intermediates:
J L Eve 0.4 (L16)
L16 is one of several designations applied to what appears to be a single J L Eve tower series. The design is similar to SWE PL16, but the crossarms are open instead of braced. “L132” appears to be another designation that is applied to these towers.
J L Eve drawing C534/273C (JE35/35693) demonstrates that the DT/DT90 tower is highly customisable according to requirements, hence the variations observed above. These variations are likely not official types but examples of adaptation according to specific requirements at each substation and cable sealing end.
Eve 0.175
Eve 0.175 is similar to L16 but was designed for 0.175□″ SCA conductors—the same as PL16—instead of the 0.4□″ SCA conductors of L16. No official designation is known.
Strengthened towers on the line between Nairn and Keith, Scotland:
J L Eve C772
J L Eve C772 is a light construction type designed for 0.125□″ SCA conductors.
Inveraray–Taynuilt
Inveraray–Taynuilt is a light construction type designed for 0.125□″ SCA conductors.
J L Eve C1415
J L Eve C1415 is a light construction type designed for 0.125□″ SCA conductors. It is a derivative of Eve C772. The recovered drawings are mostly C1824 which appears to be metricated C1415.
Quoich–Broadford
The tower type used for Quoich–Broadford is a light construction type designed for 0.125□″ SCA conductors. It is derived from the Inveraray–Taynuilt type.
L7
L7 is a higher-capacity 132 kV type: unlike other 132 kV types, L7 supports twin conductor bundles. L7 is used for replacement towers on L16 lines due to its ability to take the heavier conductors.
L4(m)
L4(m) is distinctive for its use of open, nearly isosceles crossarms instead of the conventional right triangle shape; this arrangement can also be found on the much larger 400 kV L12 and SSE400 types. D60 and D90 bear a horizontal projection at the top for the earth wire.
The bracing in red in the D60 diagram represents how D60 towers appear in reality; possibly it was mistakenly omitted from the diagram, or the design could have changed.
Although not known from any official material, there are also specially-adapted single-circuit towers. The formal designations are not known, and the diagrams depict simply the visual changes:
275 and 400 kV
L34
L34 is a flat single-circuit 275 kV type.
L66
L66 is a rare type similar to L2 and L3.
L2
L2 towers take twin conductor bundles and operate at 275 kV or 400 kV. Contrast the smaller L3 below. The T1648 line tower is included here as it was used in conjunction with L2 angle towers.
L3
Blaw Knox L3 is a scaled-down, 275 kV–only version of L2. As with L2, it is twin conductor, but designed for 0.175□″ instead of 0.4□″ conductors. There is also an Eve version of L3.
Blaw Knox L3
J L Eve L3
Blaw Knox T1521
Blaw Knox T1521 may just be a contract for an enhanced L3 line tower.
Blaw Knox T1648
Blaw Knox T1648 may just be a contract for an enhanced L2 line tower.
Blaw Knox T2175
Blaw Knox T2175 is a derivative of L3.
L6
L6 appears to be the joint tallest series in the UK along with SSE400. L6 towers are reported to have been instigated to allow quad conductor bundles (four cables strung from each crossarm), and this extra cable weight necessitated taller and stronger towers than L2.
Balfour Beatty L6
BICC L6
SF60 omitted due to chart errors.
Some towers were re-used in L6(c) below.
Reduced-height, “headless” towers can be found at Dungeness; the drawing below is approximate due to the lack of a good BICC L6 chart:
Blaw-Knox L6
J L Eve L6
Some drawings pending chart availability. Some towers were re-used in L6(c) below.
L6(c)
L6m
L8
L8 is a 275 kV and 400 kV tower series. Standard 400 kV towers:
Smaller 275 kV towers:
Like L4(m), L8 has been adapted into single-circuit form, with the series name “L8(c) Modified”:
L9
L9 is a low-height series, specifically the low-height version of L6. L9 is very similar to L12 low-height, but L9 towers suspend the cables from pairs of insulator strings in a V formation, while L12 uses simple suspension insulators.
L12
L12 is the other well-known series with near-isosceles crossarms (shared by the L12-derived SSE400). L12 however has braced crossarms and is vastly larger than L4. Note the lower deviation angles of D25 and D55 compared to the convention of D30 and D60. L12 standard height:
L12 low height:
Coylton–Auchencrosh
Coylton–Auchencrosh is a custom type used for a single line in Scotland.
L13
L13 is another replacement for L6. Information on L13 is incomplete and contradictory.
SSE400
SSE400 is a 400 kV type derived from L12 designed for the Beauly–Denny line across the Scottish highlands.
C-IVI-1
C-IVI-1 (also CIVI-1) is a single circuit 400 kV type.