UK electricity pylon series
- Series list
- 33 and 66 kV
- 132 kV
- 275 and 400 kV
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.
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Various details below are therefore incorrect and out of date.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.
See the comparisons page.
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|
|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|
|PL7||132 kV||26.76 m (87′–95⁄8″)||1938||Watshams|
|Blaw Knox K5735||132 kV||27.4 m (89′–9″) (DD2)||1941||Blaw Knox|
26.4 m (86′–9″) (D2)
26.3 m (86′–3″) (D2S)
|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|
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)
|L9||400 kV||Quad||31.7 m (104′–0″)|
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 is a 66 kV tower series. Depicted in [NSP/004/030].
This is most likely Blaw Knox.
K9906 is a 66 kV tower series. Depicted in [NSP/004/030].
This is Blaw Knox.
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 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.
Grampian pylons appear to be specific to a single line in Scotland.
SEE PL1a is a slimmer design than the Milliken towers.
SWE PL1(a)&(b) is a Callender’s type unrelated to SEE PL1a.
SEE PL1(b) is a Callender’s type.
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.
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” 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 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.
See under PL16 below.
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)”).
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 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 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 0.125 is a very small tower type designed for 0.125□″ SCA conductors. No official designation is known.
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.
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:
L7 appears to be another 132 kV type. Unlike other 132 kV types, L7 supports twin conductor bundles.
275 and 400 kV
L34 is a flat single-circuit 275 kV type.
L66 is a rare type similar to L3 and L3.
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.
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
J L Eve L3
Blaw Knox T2175
Blaw Knox T2175 is a derivative of L3.
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
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:
J L Eve L6
Some drawings pending chart availability. Some towers were re-used in L6(c) below.
L8 is a 275 kV and 400 kV tower series. Standard 400 kV towers:
Smaller 275 kV towers:
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:
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 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:
L13 is another replacement for L6. Information on L13 is incomplete and contradictory.
SSE400 is a 400 kV type derived from L12 designed for the Beauly–Denny line across the Scottish highlands.