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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 Scotland England 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 England (Scotland) 132 kV 24.0 m (78′–9″) (D2)
20.3 m (66′–9″) (S2)
1929 GEC?
SEE PL1(b) England 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 England 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 Scotland 2 × 132 kV
2 × 132 kV + 2 × 33 kV
ca. 1930 ?
SS-PL1 England Wales Scotland 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 Nothern Ireland 2 × 110 kV + 2 × 33 kV 1932 Callender’s
SEE SL4 ? 1934 Watshams
SEE SL8 33 kV ? ? Watshams
Spey Valley Scotland 132 kV + 33 kV 24.8 m (81′–4″) 1936 Blaw Knox
Blaw Knox K1373 England 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 England 132 kV 1936 Blaw Knox
PL4/WGR United Kingdom 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 Wales 66 kV ? ? ?
Lydney England 132 kV Blaw Knox?
PL7 132 kV 26.76 m (87′–958″) 1938 Watshams
Blaw Knox K5735 132 kV 27.4 m (89′–9″) (DD2) 1940 Blaw Knox
PL16 United Kingdom South Africa 132 kV 26.4 m (86′–9″) (D2)
26.3 m (86′–3″) (D2S)
1944 Blaw Knox
Blaw Knox K1201 Scotland (England Nothern Ireland) 132 kV 22.6 m (74′–3″) 1947 Blaw Knox
Blaw Knox K1420 Scotland England Wales) 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 England Scotland Northern Ireland 132 kV 26.1 m (85′–8″) J L Eve
Blaw Knox K9906 66 kV 19.8 m (65′–0″) 1947 Blaw Knox
L34 England 275 kV 25.9 m (85′–0″) 1950 Milliken or Blaw Knox
L66 England Scotland 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 Scotland 132 kV 1957 J L Eve
Inveraray–Taynuilt Scotland 132 kV 1959 ?
L6 400 kV ca. 50 m (varies) 1960 Balfour Beatty, BICC, Blaw Knox, J L Eve
Blaw Knox T1521 Scotland 275 kV 38.1 m (125′–0″) 1960 Blaw Knox
Blaw Knox T1648 Scotland 275 kV/380 kV 44.0 m (144′–3″) 1961 Blaw Knox
L7 Kenya 132 kV 26.9 m 1963 BICC and J L Eve
L9 England Scotland 400 kV 31.7 m (104′–0″) 1966 J L Eve
Blaw Knox T2175 Scotland 275 kV 38.1 m (125′–0″) 1967 Blaw Knox
J L Eve C1415 Scotland 132 kV 22.3 m (73′–3″) 1970 J L Eve
Quoich–Broadford Scotland 132 kV ?
L4(m) United Kingdom 132 kV 26.1 m 1975 Blaw Knox
L8 England Scotland Nothern Ireland (Wales) 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 Scotland 275 kV 25.2 m 1992/2001 Balfour Beatty
L13 400 kV 49.95 m Babcock
SSE400 Scotland 400 kV 50.5 m Balfour Beatty
C-IVI-1 Northern IrelandRepublic of Ireland 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 L134 intermediate (47′–0″)
Milliken L134 anchor & terminal

Milliken E102

E102 is an early secondary line type.

Milliken E102 S3
Milliken E102 S20
Milliken E102 S60

Milliken T163

T163 is an early secondary line type.

Milliken T163 D3
Milliken T163 D10

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.

SEE SL2 D60/DT

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.

[Marshall] S3
New Mills S3
[Marshall] S20
SEE SL3 S60
SEE SL3 D3
SEE SL3 D20
SEE SL3 D60
Luton–Aylesbury GPO crossing tower
DT with sealing ends [Marshall]

Milliken E177

E177 is a 33 kV type notable for having quad circuit towers.

Milliken E177 D3
Milliken E177 D10
Milliken E177 D30
Milliken E177 D30 (GPO crossing)
Milliken E177 D60
Milliken E177 D60 (GPO crossing)
Milliken E177 DT
Milliken E177 F3
Milliken E177 F72

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 SL4 S10
SEE SL4 S30
SEE SL4 D10
SEE SL4 D60
SEE SL4 DT

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.

Terminal tower

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:

K4611? line SEW
K4611? line DEW
K4611? angle SEW
K4611? angle DEW

Double circuit, standard types only:

K1373 A SEW
K1373 A DEW
K1373 A special DEW
K1373 A (no EW crossarm)
K1373 A (85° EW swing)
K1373 B SEW
K1373 B DEW
K4611 DB SEW
K4611 DC SEW, 132 kV
K4611 DB DEW
K4611 DC DEW, 132 kV
K1373 B transposition
K1373 B transposition
K1373 C
K4611 DC SEW
K4611 DC DEW
K1373 C terminal (symmetric)
K1373 C terminal (asymmetric)

Three-circuit, standard types only:

K1373 S SEW
K1373 S DEW
K1373 S 33 kV–only transposition SEW
K1373 S 33 kV–only transposition DEW
K1373 M SEW
K1373 M DEW
K1373 M transposition
K1373 M (four-tier)
K1373 D SEW
K1373 D DEW
K1373 D terminal

NWE SL4

NWE SL4 is an SL tower series designed by Milliken Brothers.

NWE SL4 D3

J L Eve C333

J L Eve C333 is a 33 kV tower series.

Eve C333 D3
Eve C333 D20
Eve C333 D60

Abergavenny and Cwmbran

Abergavenny/Cwmbran is a 66 kV tower series possibly derived from C333.

Abergavenny/Cwmbran D3
Abergavenny/Cwmbran D20
Abergavenny/Cwmbran D60
Abergavenny/Cwmbran DT

Blaw Knox K9906

Blaw Knox K9906 is a 66 kV tower series. Known examples are currently running at 33 kV.

K9906 D3
K9906 D10
K9906 D30
K9906 D60
K9906 D90
K9906 DT
K9906 DT (sealing end termination)
K9906 DT (11′ auxiliary crossarms)
K9906 DTV

L4(m) 66

L4(m) 66 is an adaptation of L4(m) for 66 kV.

L4(m) 66 D
L4(m) 66 D30

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.

Blaw Knox K1641 SCT

132 kV

PL1

See:

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:

CS PL1 A1 / S2
CS PL1 B1 / S10
CS PL1 C1 / S30
CS PL1 D1 / S60/ST
SEE PL2 ST

Double circuit:

CS PL1 A2 / D2
CS PL1 C2 / D30
CS PL1 D2 / D60/DT

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:

CE PL1 S2 (Milliken)
SS PL1 S2 (Milliken)
SWE PL1(a)&(b) S2 (Callender’s)
SS PL1 S10
PL1(c) S10
EE PL1 S30
EE PL1 S60
EE PL1 ST
SS PL1 ST (Glenlee etc)

Double circuit:

EE PL1 D2
SWE PL1 D2
SWE PL1 D10
EE PL1 D30
NWE PL1 D30
EE PL1 D60
SWE PL1 D60
EE PL1 DT
SWE PL1 DT
SWE PL1 DT60
SWE PL1 DT60A
SWE PL1 DT-type Junction
EE PL1 DT90
CE PL1 LNE terminal
NWE PL1 transposition tower

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:

Line tower, double circuit
Angle tower 1, double circuit
Angle tower 2, double circuit
Transposition tower, double circuit

Double circuit 132 kV plus double circuit 33 kV:

Line tower, quad circuit
Angle tower 1, quad circuit
Angle tower 2, quad circuit
Transposition tower, quad circuit

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 PL1a S2
SEE PL1a S30
SEE PL1a S60
SEE PL1a ST45
SEE PL1a ST90
SEE PL1a D2
SEE PL1a D30
SEE PL1a D60
SEE PL1a D90
SEE PL1a DT/DT45
SEE PL1a DT90
SEE PL1a DX

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).

SEE PL1(b) S2
SEE PL1(b) S30
SEE PL1(b) S60
SEE PL1(b) D2
SEE PL1(b) D30
SEE PL1(b) D60
SEE PL1(b) DX
SEE PL1(b) DT
SEE PL1(b) DT90

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:

S, 132/33 kV single earthwire
S, 132/33 kV double earthwire
S, 132/33 kV with spire
Transposition, 132/33 kV
M, 132/33 kV, single earthwire
M, 132/33 kV, double earthwire
D, 132/33 kV
D, 132/33 kV, short peak

Uprated 132 kV double circuit towers:

S, 132/132 kV
S, 132/132 kV with spire
Transposition, 132/132 kV with spire
M, 132/132 kV
M, 132/132 kV, short peak
D, 132/132 kV
D, 132/132 kV, short peak
D, 132/132 kV with spire

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.

CE PL3 S2 SEW
CE PL3 S10 SEW
CE PL3 S30 SEW
CE PL3 S30 DEW
CE PL3 S60 SEW
CE PL3 S60 DEW
CE PL3 D10 SEW
CE PL3 D10 DEW
CE PL3 D30 SEW
CE PL3 D30 DEW

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”.

PL4 S2
PL4 S30
PL4 S60
PL4? S90?
CE PL4 D2
CE PL4 DD2
CE PL4 D10
CE PL4 DD10
CE PL4 D30
CE PL4 DD30
CE PL4 D60
CE PL4 DD60
CE PL4 D90
CE PL4 DD90
CE PL4 DDT90 “A”
CE PL4 DDT90 “B”
PL4 DDT90 variant 1
PL4 DDT90 variant 2

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.

Lydney line tower (DD2 E20?)
Lydney DDT

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.

SEE PL7 D2
SEE PL7 DD2
SEE PL7 D10
SEE PL7 DD10
SEE PL7 D30
SEE PL7 DD30
SEE PL7 D60
SEE PL7 DD60
SEE PL7 DT
SEE PL7 DT (ETC)
SEE PL7 DDT
SEE PL7 DDT (ETC)
SEE PL7 DDT90

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.

Blaw Knox K5735 DD2
Blaw Knox K5735 DD30
Blaw Knox K5735 DD60
Blaw Knox K5735 DD90

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!

SWE PL16 D2
STL1 K9857 D2 (PL16 D2S)
SWE PL16 DD2
STL1 K9857 DD2 (PL16 DD2S)
SWE PL16 D10
SWE PL16 DD10
SWE PL16 D30
SWE PL16 DD30
SWE PL16 D60
SWE PL16 DD60
SWE PL16 D90
SWE PL16 DD90
D60 Junction (D60J)
D90 Junction (D90J)
SWE PL16 DT
SWE PL16 DT90
SWE PL16 DDT
SWE PL16 DDT90
K1124B DT through-line

Classed as PL16 for now:

T1073 S30 (rotated base)
T1073 S60 (rotated base)

Blaw Knox K1201

Blaw Knox K1201 is a single-circuit companion suite to PL16 designed for Scotland.

K1201 S2
K1201 SS2
K1201 S10
K1201 SS10
K1201 S30
K1201 SS30
K1201 S60
K1201 ST
K1201 SST

Strengthened towers:

K1201 S2

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.

Blaw Knox K1420 S10
Blaw Knox K1420 S30
Blaw Knox K1420 S60
Blaw Knox K1420 ST

Associated intermediates:

Steel lattice tower (route XCW)
Suspension pole (SWE region)
Suspension pole (NOSHEB region variant 2)

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 (L16) D2
J L Eve (L16) D10
J L Eve (L16) D30
J L Eve (L16) D60
J L Eve (L16) D90
J L Eve (L16) DT/DT90
J L Eve (L16) DT variant 2
J L Eve (L16) DT variant 2/+1
J L Eve (L16) DT variant 2/+2
J L Eve (L16) DT variant 3
J L Eve (L16) DT variant 4
J L Eve (L16) DT variant 5/+1
J L Eve (L16) DT90
J L Eve (L16) universal crossunder gantry

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.

Eve 0.175 D2
Eve 0.175 D2 (uplift)
Eve 0.175 DD2
Eve 0.175 D10
Eve 0.175 D30
Eve 0.175 D60
Eve 0.175 DT
Eve 0.175 DT variant 2
Eve 0.175 DT variant 3
Eve 0.175 DT90

Strengthened towers on the line between Nairn and Keith, Scotland:

Eve 0.175 D2
Eve 0.175 D10
Eve 0.175 D10 (Keith)
Eve 0.175 D30
Eve 0.175 D60

J L Eve C772

J L Eve C772 is a light construction type designed for 0.125″ SCA conductors.

Eve C772 D2
Eve C772 D10
Eve C772 D30

Inveraray–Taynuilt

Inveraray–Taynuilt is a light construction type designed for 0.125″ SCA conductors.

T1498 D2L
T1498 D30L
T1498 D60L
T1498 D90L

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.

Eve C1824 D2
Eve C1824 D10
Eve C1824 D30
Eve C1824 D60
Eve C1824 DT
Eve C1824 DT (ETC)

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.

L7 or L7(c) D (BICC)
L7(c) D30 (J L Eve)
L7(c) D60 (J L Eve)
L7(c) D90 (BICC)
L7(c) DT (J L Eve)
L7(c) DT (basic crossarms)
L7(c) DJT (BICC)
L7(c) ST (J L Eve)
L7(c) SF60 0–30°
L7(c) SF60 30–60°

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.

L4(m) D STD
L4(m) D30 STD
L4(m) D60 STD
L4(m) D90 STD
L4(m) DT STD
L4(m) DJT STD
L4(m) ST STD
L4(m) SF60 STD
L4(m) SF60 M6

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:

L4(m) S (A)
L4(m) S (B)
L4(m) S30 (A)
L4(m) S30 (B)
L4(m) S60 (A)

275 and 400 kV

L34

L34 is a flat single-circuit 275 kV type.

L34 S1
L34 S10
L34 S30
L34 S60

L66

L66 is a rare type similar to L2 and L3.

L66 D2 STD
L66 D30 STD
L66 D60 STD

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.

L2 D
L2 D DMC
L2 D10
L2 D15 EWCO
L2 D30
L2 D30 DMC
L2 D40 EWCO
L2 D60
L2 D60 DMC
L2 D90
L2 DJ
L2 DJX
L2 DT
L2 DTU (0–5° entry)
L2 DT45
L2 ST
L2 STX
L2 380ST
L2 SFX MH
L2 SFX E16

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

Blaw Knox L3 D
Blaw Knox L3/L3(c) DS
Blaw Knox L3/L3(c) D10
Blaw Knox L3/L3(c) D30
Blaw Knox L3/L3(c) D40 EWCO
Blaw Knox L3/L3(c) D60
Blaw Knox L3 DJ
Blaw Knox L3 DJX
Blaw Knox L3 DT
Blaw Knox L3 DTV45/DTU45 (0-5° entry)
Blaw Knox L3 ST

J L Eve L3

J L Eve L3 D (C673)
J L Eve L3 D (C864)
J L Eve L3 D10
J L Eve L3 D30
J L Eve L3 D60
J L Eve L3 DT

Blaw Knox T1521

Blaw Knox T1521 may just be a contract for an enhanced L3 line tower.

T1521 D

Blaw Knox T1648

Blaw Knox T1648 may just be a contract for an enhanced L2 line tower.

T1648 D

Blaw Knox T2175

Blaw Knox T2175 is a derivative of L3.

T2175 D
T2175 D10
T2175 D30
T2175 D60

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

L6 BB D STD
L6 BB D20EC STD
L6 BB D30 STD
L6 BB D40EC STD
L6 BB D60 STD
L6 BB D90 STD
L6 BB DJT STD
L6 BB DT STD
L6 BB ST STD
L6 BB SF60 5–30° STD

BICC L6

SF60 omitted due to chart errors.

Some towers were re-used in L6(c) below.

L6 BICC D STD
L6 BICC D20EC STD
L6 BICC D30 STD
L6 BICC D40EC STD
L6 BICC D60 STD
L6 BICC D90 STD
L6 BICC DT STD
L6 BICC DJT STD
L6 BICC ST STD

Reduced-height, “headless” towers can be found at Dungeness; the drawing below is approximate due to the lack of a good BICC L6 chart:

Dungeness “headless” L6 BICC D30 M20′

Blaw-Knox L6

L6 BK D STD
L6 BK D30 STD
L6 BK D60 STD
L6 BK D90 STD
L6 BK DT STD
L6 BK DJT STD
L6 BK ST STD
L6 BK SF60 STD

J L Eve L6

Some drawings pending chart availability. Some towers were re-used in L6(c) below.

L6 JLE D STD
L6 JLE D20EC
L6 JLE D30
L6 JLE D40EC STD
L6 JLE D60 STD
L6 JLE D90 STD
L6 JLE DJT STD
L6 JLE SF60

L6(c)

L6(c) D STD (BICC)
L6(c) D30 STD (J L Eve)
L6(c) D60 STD (BICC)
L6(c) D90 STD (J L Eve)
L6(c) DJT STD (J L Eve)
L6(c) DT STD (BICC)
L6(c) SF60 STD 0–15° (BICC)
L6(c) SF60 STD 15–45° (BICC)
L6(c) SF60 STD 45–60° (BICC)

L6m

L6m D STD
L6m D30 STD
L6m D60 STD
L6m DJT STD
L6m ST STD

L8

L8 is a 275 kV and 400 kV tower series. Standard 400 kV towers:

L8(c) D STD
L8(c) D30 STD
L8(c) D60 STD
L8(c) D90 STD
L8(c) DT STD
L8(c) DJT STD
L8(c) ST M7.3 (M24′)
L8(c) SF60 STD 0–20°
L8(c) SF60 STD 20–60°

Smaller 275 kV towers:

L8 RD STD
L8 RD M4.9 (M16′)
L8 RD M7.3 (M24′)

Like L4(m), L8 has been adapted into single-circuit form, with the series name “L8(c) Modified”:

L8(c) Modified S STD
L8(c) Modified S60 STD

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.

L9 LD

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 D STD
L12 D10 STD
L12 D25 STD
L12 D35EC STD
L12 D55 STD
L12 D90 STD
L12 DT Mk 1 STD
L12 DT STD

L12 low height:

L12 LD STD
L12 LD30 STD

Coylton–Auchencrosh

Coylton–Auchencrosh is a custom type used for a single line in Scotland.

Line tower, std. height
10° tower, std. height
30° tower, std. height
60° tower, std. height
Terminal tower, std. height

L13

L13 is another replacement for L6. Information on L13 is incomplete and contradictory.

L13 D
L13 D60
L13 LD

SSE400

SSE400 is a 400 kV type derived from L12 designed for the Beauly–Denny line across the Scottish highlands.

SSE400 D/DL
SSE400 D (lower strength)
SSE400 D10
SSE400 D25
SSE400 D55
SSE400 D90
SSE400 DT

C-IVI-1

C-IVI-1 (also CIVI-1) is a single circuit 400 kV type.

C-IVI-1 intermediate
C-IVI-1 angle (30°/60°/90°)