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UK electricity pylon series

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Overview

This page provides a visual overview of most of the major UK electricity pylon (transmission tower) types found within Great Britain; 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.

See the guide page for designation and recognition information.

Caveat

Work is currently in progress on understanding the PL (primary line) and SL (secondary line) designations. The PL numbers do not refer to tower suites but contract numbers, so please be careful about how you use them at this stage. Certain types may move to new pages that are independent of the various contracts under which the towers were used, for example PL2 seems to have used the same Milliken towers as most of PL1. PL1(a) can refer to at least two separate designs according to region, and the Watshams type was used in numerous contracts.

Various details below are therefore incorrect and out of date. The individual pages will not be updated until a means is found of referring to the various types without regard to which contracts they were used for. It is not known when such a breakthrough will ever occur, so this page may remain out of date for some time. Brief notes regarding current information are marked with the icon displayed against this paragraph.

Comparisons

See the comparisons page.

Series list

Earliest known date does not indicate the date that the type was introduced; 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.

Series Voltage Conductors Height (D/D2) Earliest known date Designer
K721 66 kV 1930 Blaw Knox
K9906 66 kV Blaw Knox
PB 132 kV Painter Brothers
PL1 132 kV Single Milliken
SEE PL1a 132 kV Single 1929 GEC?
SEE PL1(b) 132 kV Single 1929 Callender’s
CE PL3 132 kV 1936 Blaw-Knox
PL4/WGR 132 kV 26.2 m (86′–0″) 1936 Blaw-Knox
Lydney 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) 1941 Blaw Knox
PL16 132 kV Single 26.4 m (86′–9″) (D2)
26.3 m (86′–3″) (D2S)
1944 Blaw-Knox
L16/L55 132 kV Single 27.1 m (88′–10″) J L Eve
Eve 0.175 132 kV Single 85′–8″ (26.1 m) J L Eve
Eve 0.125 132 kV Single J L Eve
L34 275 kV Twin 25.9 m (85′–0″) 1950 Milliken or Blaw-Knox
L66 275 kV Twin 34.3 m (115′–3″) Blaw-Knox
L2 275 kV/380 kV/400 kV Twin 41.6 m (136′–6″) 1952 Blaw-Knox
L3 275 kV Twin 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
Blaw Knox T2175 275 kV Single 38.1 m (125′–0″) 1967 Blaw-Knox
L4 132 kV, 66 kV Single 26.1 m 1975 Blaw-Knox
L6 400 kV Triple, quad ca. 50 m (varies) 1960 Balfour Beatty, BICC, Blaw-Knox, J L Eve
L7 132 kV Single, twin 26.9 m BICC and J L Eve
L8 400 kV, 275 kV Twin 46.4 m (400 kV)
ca. 40 m (275 kV)
Blaw-Knox?
L9 400 kV Quad 31.7 m (104′–0″)
L12 46.5 m (standard height)
35.3 m (low height)
L13 400 kV 49.95 m
SSE400 400 kV Twin 50.5 m Balfour Beatty

Dashed outlines for suspension insulators are approximations based on photos that have been added to diagrams that omitted insulator details. These have been added for clarity.

33 and 66 kV

K721

K721 is a 66 kV tower series. Depicted in [NSP/004/030].

This is most likely Blaw Knox.

K9906

K9906 is a 66 kV tower series. Depicted in [NSP/004/030].

This is Blaw Knox.

132 kV

PB

PB is a single circuit, horizontally-arranged 132 kV tower series from Painter Brothers.

Painter Brothers also built the test version of L2, so “PB” is probably not a real designation.

PL1

PL1 is reported to be the UK’s first standardised tower design, although the design pre-dates the PL1 designation. PL1 was the tower type used to build the original National Grid at 132 kV. It has been suggested that PL1b is essentially the same type, with minor modifications, while PL1a is distinctly different.

Milliken PL1 towers broadly appear to have been constructed to two designs: original Milliken and revised Milliken. The first Milliken PL1 towers constructed in the UK were in the Central Scotland scheme, CS PL1. The two types have been referred to as “CS-PL1” and “SS-PL1” (South Scotland PL1 scheme) [Standard Tower Types] and we know that SS PL1 is the revised type.

All indications are that PL1b is different. SWE PL1(a)&(b) and SEE PL1b are Callender’s types.

Single circuit:

Milliken (1928) S2
SS PL1 S2 (Milliken)
SWE PL1(a)&(b) S2 (Callender’s)
Milliken (1928) S10
SS PL1 S10S (Milliken)
Milliken (1928) S30
Milliken (1928) S60/ST

Double circuit:

Milliken (1928) D2
EE PL1 D2 (Milliken)
SWE PL1 D10
Milliken (1928) D30
EE PL1 D30 (Milliken)
Milliken (1928) D60/DT
EE PL1 D60 (Milliken)
EE PL1 DT (Milliken)
EE PL1 DT90 (Milliken)
PL1 transposition tower

Grampian

Grampian pylons appear to be specific to a single line in Scotland.

Grampian D2

SEE PL1a

SEE PL1a is a slimmer design than the Milliken towers.

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

SWE PL1(a)&(b) is a Callender’s type unrelated to SEE PL1a.

SEE PL1(b)

SEE PL1(b) is a Callender’s type.

SEE PL1(b) S2
SEE PL1(b) D2
SEE PL1(b) D30
SEE PL1(b) D60
SEE PL1(b) DX

CE PL3

CE PL3 appears to be the precursor to CE PL4.

Blaw Knox CE PL3 is similar to CE PL4 and appears to be a short-lived, older design without proper earthwire peaks on the angle towers. Single and double circuit.

CE PL3 S2
CE PL3 D30 (Blaw Knox)
CE PL3 DD30 (Blaw Knox)

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”.

CE PL4 D2 (Blaw Knox)
CE PL4 DD2 (Blaw Knox)
CE PL4 D10 (Blaw Knox)
CE PL4 DD10 (Blaw Knox)
CE PL4 D30 (Blaw Knox)
CE PL4 DD30 (Blaw Knox)
CE PL4 D60 (Blaw Knox)
CE PL4 DD60 (Blaw Knox)
CE PL4 D90 (Blaw Knox)
CE PL4 DD90 (Blaw Knox)
CE PL4 DDT90 “A” (Blaw Knox)
CE PL4 DDT90 “B” (Blaw Knox)
PL4 DDT90 variant 1
PL4 DDT90 variant 2

Lydney

Lydney” is a temporary designation for towers found around Lydney, Gloucestershire. There is no visual material from which diagrams can be produced. 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.

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

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.

K5735 DD2

STL1

See under PL16 below.

PL16

PL16 contains more than one design for the D2 and DD2 towers; the known variants are SWE and “Scottish” (both Blaw Knox). The remainder of the tower types appear to have only a single design. The “Scottish”-style D2 towers bear some resemblance to the PL1 family and PL4. The “Scottish” D2 types appear to be widespread in England, while the SWE D2 type can be found in Scotland!

In Scotland, these towers were constructed to specification STL1. STL1 contains double and single circuit (including single circuit double earthwire) and flat formation single circuit towers with no earthwire. SWE PL16 single circuit remains unconfirmed. “PL16” is now a catch-all classification within the UK power industry of uncertain scope, which may or may not (depending on your source) include non-Lynx towers. The “Scottish” towers refer to STL1. STL1 D2 became PL16 D2S (also “D2(S)”).

“Scottish” (K1201) S2
“Scottish” (K1201) S60
“Scottish” (K1201) ST
“Scottish” (K1201) SST
T1073 S30 (rotated base)
T1073 S60 (rotated base)
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
SWE PL16 DT
SWE PL16 DDT

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)

L16/L55

L16 and L55 are designations applied to what appears to be a single J L Eve tower series. Eve appeared not to use series designations and it seems likely that L16 and L55 are both external designations for the same 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 DT90

Eve 0.125

Eve 0.125 is a very small tower type designed for 0.125″ SCA conductors. No official designation is known.

Sloy–Carradale D2
Sloy–Carradale D10
Dunoon D2
Dunoon D10

L4

L4 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.

L4m D STD
L4m D30 STD
L4m D60 STD
L4m D90 STD
L4m DT STD
L4m DJT STD
L4m ST STD
L4m 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 S (A)
L4 S (B)
L4 S30 (A)
L4 S30 (B)
L4 S60 (A)

L7

L7 appears to be another 132 kV type. Unlike other 132 kV types, L7 supports twin conductor bundles.

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°

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 L3 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
T1648 D
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 version of L2 that is 275 kV only. As with L2, it is twin conductor. 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 DT45?
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 T2175

Blaw Knox T2175 is a derivative of L3.

T2175 D STD
T2175 D10 STD
T2175 D30 STD
T2175 D60 STD

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.

BES L6 D (1960)
BEBS L6 D (1966)

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 400 kV
L8(c) D30 STD 400 kV
L8(c) D60 STD 400 kV
L8(c) D90 STD
L8(c) DT STD 400 kV
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, L8 has been adapted into single-circuit form; as with L4, the designations are not known and those given below are only suggestions:

L8 S 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 D2

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 400 kV
L12 D10 400 kV
L12 D25 400 kV
L12 D55 400 kV
L12 D90 400 kV
L12 DT Mk 1
L12 DT 400 kV

L12 low height:

L12 LD

L13

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

L13 D
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