PL4/WGR

Contents
- Overview
- Can be confused with
- Lines
- Tower forms
- Single circuit
- Double circuit
- Tower details
- See also
Overview
PL4 is a UK electricity pylon (steel lattice transmission tower) series. PL4 is one of only a few series to support double earthwires, doing so with separate earthwire crossarms. PL4 appears to be a revision of CE PL3 that added extra clearance to the earthwire (or earthwires in the case of double earthwire towers).
The towers were designed for scheme CE (Central England) PL4. The name has been simplified to “PL4” as it has been used for later schemes across the UK. The series is also known as “WGR” (Wartime Grid Reinforcement) as it was used for various new lines constructed during World War II.
General data
Contractor | Blaw Knox |
---|---|
Found | |
Height (straight line tower) |
86′–0″ (26.2 m) 91′–3″ (27.8 m) (double earth) |
Voltage | 132 kV |
Dates back to | 1936–37 (drawings) |
Design conductor | 0.175□″ SCA (now 175 mm² Lynx ACSR) |
Known heights |
STD E5 (+5′) (only listed for D2) E10 (+10′) E20 (+20′) E30 (+30′) (not listed for D30) E20+10′ (+30′) (only listed for D10) |
Circuit count | Single, double |
E20+10′ denotes an E20 extension plus another 10′ extension for a total of 30′ extra height, rather than a separate design as with the normal E30.
WGR
[Standard Tower Types] refers to this design as “WGR (or PL4)”. This reflects the fact that the design was adopted for the Wartime Grid Reinforcement (or War Time Grid) schemes. The Wartime Grid Reinforcement accounts for these towers being found outside of the CE region. Scheme WGR PL1 is the V route from Harker to Galashiels; this is the only WGR scheme identified by name at present, but quite a few were constructed across the UK.
The drawing schedule for WGR lists numerous drawing ranges; without examining a sample of each range it’s not possible to determine what each range represents.
Contract | XM range | Description | Usage |
---|---|---|---|
K1611 | XM1276 | CE PL3 | Various details, single and double circuit; general arrangement drawings for S2, S10, S30 and S60 |
K1857 | XM1317 | CE PL4 | Various, including general arrangement and erection diagrams for double circuit towers |
K2231 | ? | ? | Various details, double circuit only |
K2737 | ? | ? | Various details, including single circuit towers |
K5297 | ? | ? | Various details, including erection diagrams for single circuit towers |
? | XM1363 | ? | Various general arrangement drawings |
? | XM1425 | ? | Various (double circuit) |
? | XM1525‡ | ? | Various (double circuit) |
? | XM1692 | ? | General arrangement drawings for single circuit towers; possibly K5297 |
K5784 | XM1746 | War Time Grid | Various details |
? | XM1857 | ? | Erection diagram for 20 foot extension, D10/DD10 |
‡ With only one known drawing, one would think that this is a typing mistake for XM1425 but the large leap in BK35 numbering makes it impossible to be sure.
Can be confused with
- PL16
- CE PL3
- Blaw Knox K1201 (single circuit)
Lines
Various lines have been found to date. A few are confirmed and detailed below:
Double-circuit lines confirmed so far:
- Harker to Galashiels, WGR PL1 (V route)
- Leicester to Corby, split into two sections:
- Leicester substation to Kibworth substation (route AZT); both ends terminate on PL16 towers. The penultimate tower at Leicester is a Milliken SS-PL1 D60, and there is a stray Milliken-like DT at the substation.
- Kibworth substation to Corby substation (route AZ); between Hazelwood 33 kV substation and the Midland Main Line railway, the line has been undergrounded. All four ends terminate on PL16 towers.
- Corby to Eaton Socon substation, St Neots (route PFZ); this is said to be Corby to Little Barford, although Eaton Socon substation to Little Barford substation is now the short L7(c) route PGH. Around Grafham Water there are Eve 0.4 towers; the exact extent of these towers cannot be determined due to the line’s distance from roads.
Tower forms
The K5784 War Time Grid Reinforcement drawing schedule includes both single and double circuit towers. Single-circuit WGR lines have yet to be identified however.
The following diagrams are shown to scale at 12 pixels per metre.
Single circuit
The single-circuit diagrams above are based primarily on the line from Bridgwater to Taunton, which is primarily SWE PL1(a)&(b) but the last stretch is a revised form of CE PL3 that is almost certainly PL4. The line tower diagram is cloned from CE PL3 as it appears to be identical.
LSTC gave the S60 tower as “PL9” when drawing up material for line alterations for a new housing estate in Staplegrove; this designation has not been explained.
An S60 tower can also be found at Cargenbridge, near Dumfries. This is listed on the tower schedule as type “NWE”. No such NWE line has yet been identified.
The tower suggested to be an S90 can be found outside Taunton substation, carrying an 84° deviation; this is the least accurate due to the lack of good viewing angles from Google Street View. There is no visual reason why this would be PL4 and not K1201; the other angle towers differ in crossarm bracing between PL3/PL4 and K1201.
Double circuit
Details on the terminal towers are unclear. CEA drawing ED51147 names the type as “D.D.T.90°.TOWER” but specifically shows the tower without auxiliary crossarms (omitted from the side view). Variants “A” and “B” are depicted as per drawing ED51147, without auxiliary crossarms. However, there most certainly are PL4 DDT90 towers with auxiliary crossarms. Variant 1 above is depicted with a preliminary depiction of the auxiliary crossarms as seen on a WGR tower at Upper Boat Substation, South Wales (between Pontypridd and Treforest Industrial Estate, 51.576° N 3.297° W). The next tower is a DD60 (51.576° N 3.294° W), after which the line changes to PL16. DDT90 variant 2 depicts the WGR tower found in Watford, Hertfordshire, England (see links below) with a longer middle auxiliary crossarm. There is also a terminal tower at Blackburn Substation (see links below) without auxiliary crossarms that would better fit the description of DDT.
ED51147 was drawn on 18/12/1956 and originally covered only a single design. Variant “B” was added on a date that one would presume says “7·5·58” (because “7·5·56” would make no sense as an amendment); this second variant represents a tower used in or at “Sundon”, presumably Sundon Substation, a tower that appears to no longer exist. Variant B is simply Variant A without the extended length top crossarms; the remainder of the tower is identical.
Tower details
Crossarm width is the total width across the widest crossarm.
Type | Source | Height | Base width | Crossarm width |
---|---|---|---|---|
CE PL4 D2 | K1857-8F | 86′–0″ (26.2 m) | 16′–0 (4.9 m) | 32′–0″ (9.8 m) |
CE PL4 DD2 | ED51108 (Tower Bible) | 91′–3″ (27.8 m) | 16′–01⁄8″ (4.9 m) | 32′–0″ (9.8 m) |
CE PL4 D10 | ED51114 (Tower Bible) | 84′–9″ (25.8 m) | 18′–0″ (5.5 m) | 29′–6″ (9.0 m) |
CE PL4 DD10 | ED51116 (Tower Bible) | 88′–3″ (26.9 m) | 18′–0″ (5.5 m) | 29′–6″ (9.0 m) |
CE PL4 D30 | ED51121 (Tower Bible) | 84′–3″ (25.7 m) | 22′–0″ (6.7 m) | 32′–0″ (9.8 m) |
CE PL4 DD30 | ED51124 (Tower Bible) | 87′–9″ (26.7 m) | 22′–0¼″ (6.7 m) | 32′–0″ (9.8 m) |
CE PL4 D60 | ED51130 (Tower Bible) | 85′–9″ (26.1 m) | 23′–0″ (7.0 m) | 33′–6″ (10.2 m) |
CE PL4 DD60 | ED51134 (Tower Bible) | 89′–3″ (27.2 m) | 23′–0″ (7.0 m) | 33′–6″ (10.2 m) |
CE PL4 D90 | ED51138 (Tower Bible) | 85′–9″ (26.1 m) | 23′–0″ (7.0 m) | 38′–6″ (11.7 m) |
CE PL4 DD90 | ED51141 (Tower Bible) | 89′–3″ (27.2 m) | 23′–0″ (7.0 m) | 38′–6″ (11.7 m) |
CE PL4 DDT90 | ED51147 (Tower Bible) | 89′–3″ (27.2 m) | 23′–0″ (7.0 m) | 50′–0″ (15.2 m) |
See also
- V route (WGR PL1), Harker to Galashiels (Flickr)
- Assorted WGR towers (Flickr)
- WGR DDT90 and PL1a DT90, Watford 132 kV substation (Flickr)
- PL4 or WGR DDT, and PL16 DT at Blackburn Substation
- WGR PL1 DD30, Carlisle (Flickr)
- WGR PL1 DD90, Carlisle (Flickr)