Blaw Knox K1420

Contents

• Overview
  • General data
• Lines
• Tower forms
• Tower details
• See also

Overview

K1420 is a suite of flat-formation single-circuit angle towers, possibly derived from PL16 gantries. The K1420 contract number was used for STL1-compliant designs for NoSHEB; the designation within England and Wales remains unknown. K1420 is not known to contain a line tower and it is used without earthwire support.

K1420 primarily provides angle towers for 132 kV wood pole lines; such lines can be found in Scotland, Wales and England. This practice—wood pole intermediates with lattice angle towers—is also used extensively across Ireland for the single-circuit lines. Northern Ireland uses Blaw Knox K1641 lattice angle towers instead of K1420 for this purpose. The Republic of Ireland uses a curious design of angle tower where the centre conductor has to be routed around the tower body on pilot insulator sets.

K1420 angle towers are also used with an unidentified design of single circuit line tower. Curiously, the line tower has a conventional triangular arrangement of conductors, unlike the flat formation wood poles that K1420 is more commonly used with.

Towers matching K1420 are occasionally used as gantries at PL16 junctions, such as one at Well End in Borehamwood, Hertfordshire, England; these may however be standard PL16 gantries. K1420 was also used along the Corrieyairack Pass in Scotland, where a double circuit STL1 (“PL16”) line split into two single circuit lines. This route has since been replaced by the Beauly–Denny line.

General data

Designer	Blaw Knox, Milliken Brothers branch
Found
Height	42′–6″ (13.0 m) (S10)
Voltage	132 kV
Dates back to	1947 (drawings)
Conductors	Single
Circuit count	Single

Lines

Lines confirmed so far:

• Scotland:
  • Kintore Grid Supply Point to Fiddes (routes XCW and CF). From Kintore to just south of the River Dee, the intermediates are single circuit towers of an unknown type. From this point onwards to Fiddes, various types of wood pole are used, with sections being an assortment of wood pole types and K1420 steel towers. Tower CF1 is a K1420 S10 at Fiddes. The change from XCW (from the Kintore end) to CF (from the Fiddes end) appears to be a junction south of Countesswells where the two lines meet across a double circuit line from Tarland to Airyhall.
  • Fiddes to Brechin Grid (route FB); wood poles with the occasional K1420 tower
  • Brechin Grid to a junction with Tealing to Brechin (route TBN); wood poles with the occasional K1420 tower
  • The spur to Nant power station, which tees off the line between Inveraray and Taynuilt north of Kilchrenan, uses K1420 angle towers and the unidentified lattice intermediates initially, before changing over to K1201
• Wales:
  • Caernarfon–Pentir (route CY)
  • Amlwch to near Wlyfa, Anglesey (route DD)
  • Rhos Substation to Aberystwyth Substation (including the spur to Llanarth Substation)
  • Rhos Substation to Rhydlydan Substation (including the spur to Lampeter Substation)
  • Route 4ZC (Pentir–Trawsfynydd) carries 132 kV on the west circuit from Trawsfynydd up to Glan-Dwyfach (west of Garndolbenmaen), where the 132 kV circuit separates out on a wood pole line heading west to Y Ffor substation. (The west circuit from Glan-Dwyfach to Pentir is currently disconnected, but this is intended to change in the future.)
• England:
  • Between Hayle and Rame substations in Cornwall. This line begins as double circuit before dividing into two single circuit lines: wood pole and K1420 to Rame, and Painter Brothers to Fraddon.

Both of the respective terminal towers at Rhos Substation use K1420 ST terminal towers. Another ST is used at the tee for the spur to Lampeter Substation. At Rhydlydan Substation the line terminates on a K1420 ST; there is also an outbound line on “Trident” poles.

Tower forms

K1420 towers, shown to scale at 12 pixels per metre:

Associated intermediates:

The lattice tower diagram is scaled to the enhanced PL3/PL16 phase clearances, yielding a fairly short tower, but its actual dimensions are not known. The dimensions of the wood poles are also not known; they are simply guesswork based on estimated ground clearance and similarity in size to K1420.

Tower details

Crossarm width is the total width across the single crossarm.

See also

• Corrieyairack Pass gantries, since removed (Flickr)
• K1420 ST used at a PL16 junction in what appears to be England (Flickr)
• K1420 ST, Rheidol, Wales (Alamy)