Riley and Neate masts

Contents

• Overview
  • General data
  • Characteristics
  • Uprating
• Lines
  • General data
  • Existing lines
• Tower forms
  • H99
  • Darlington to Richmond
  • Newton Aycliffe to Darlington
• Tower details
• Locations

Overview

Winchester firm Riley and Neate designed a suite of 66 kV single-circuit steel supports in the 1940s for the North Eastern Electric Supply Company (NESCo). These lines should have used wood poles, but a shortage of suitable wood during wartime meant that steel was chosen instead. All the structures are self-supporting, but Riley and Neate used the term “mast” for the rectangular-section straight line and 10° angle supports and “self-supporting angle tower” for the higher angle supports. Over 100 km of these lines were constructed between 1942 and 1948. [EDS] [NSP/004/030]

In the mid-2000s, the line between Darlington North Substation and Richmond was uprated from 66 kV to 132 kV. The line masts were converted to use rod insulators while the angle towers were replaced with new designs from Balfour Beatty. The line from Darlington to Newton Aycliffe (Skerneside substation) also received the 132 kV line tower upgrades, but the angle towers were merely strengthened and the line is de-rated to 33 kV.

The digitised drawings for H99—those that were even recovered—are in poor condition and a considerable portion of the text has limited legibility or is obliterated.

These so far are the only steel masts or towers that Riley and Neate are known to have designed.

General data

Designed for	NESCo (North Eastern Electric Supply Company)
Design contractor	Riley and Neate EDS Consultancy (132 kV uprating) Balfour Beatty (replacement S10 and S60)
Found
Height (straight line mast)	42′–0″ (12.8 m)
Voltage	66 kV (design) 132 kV (uprating)
Dates back to	1940 (drawings) 1942–48 (construction)
Circuit count	Single
Design conductor	0.1□″, 0.15□″ and 0.2□″ HDBC
Design earthwire	?
Standard span	90 m (ca. 295 feet)

Characteristics

Riley and Neate made some interesting decisions when designing the towers.

With most steel tower lines, one or more earthwires are placed above the phase conductors to shield them from lightning strikes. Riley and Neate lines have the earthwire on the lower tier where it is shielded by the phase conductor above! At least one contract (H99-10) did not use an earthwire or earthwire arms.

The supports are designed to carry a pilot wire. The details of this are not clear. Northern Powergrid note in [NSP/004/030] that a line may have a “pilot cable supported by a catenary wire” or a “catenary wire only”. Riley and Neate drawings clearly indicate that the fourth arm supports the earthwire, and for the line tower they depict the “stitch eyebolt” that holds the “stitch wire” (a catenary term). Northern Powergrid also noted:

On some designs the catenary wire also operated as an aerial earthwire bonding all supports to earth at the remote ends of the circuit as opposed to each support being individually earthed.

Northern Powergrid did not clearly indicate what role they believe the catenary wire played, but it seems to have been a dual-function wire that provided earthing as well as carrying the pilot wire. Few tower types were designed to support pilot wires; another type was the slightly earlier Blaw Knox K1373.

The standard span is given by Northern Powergrid as 90 metres in [NSP/004/030]. This is roughly 295 feet, which is much shorter than the 900 or 1000 foot span of 132 kV towers. Maximum span is 108 m (around 354 feet); with a pilot wire fitted, the maximum span is reduced to 104 m (around 341 feet). Note that these are modern metric measurements and do not necessarily reflect the original imperial figures. For example, the original standard span might have been 300 feet.

Northern Powergrid give the angles as 10°, 30°, 50° and 60° in [NSP/004/030] but no original drawing numbers are given for a 30° tower, only an EDS drawing number. There is no known 30° tower; the jump from 10° angle to 50° angle may be unique. Riley and Neate drawings mention a 72° tower, but neither the drawings for it nor any such tower have been found.

Riley and Neate’s design is unusual (and possibly unique in Britain) for supporting high angles on suspension insulators. The crossarms designed for the angle towers (up to 72°) can be used with either tension or suspension insulators. No examples are now known of 50° and higher angles on suspension insulators; one 10° mast outside Peterlee retains its suspension configuration having been changed over to polymeric insulators.

Curiously, Riley and Neate also omitted cattle guards from their towers. These were of course included in Balfour Beatty’s S10 and S60 towers.

Uprating

EDS Consultancy were commissioned to appraise the Riley and Neate structures, and they devised a way to uprate the supports from 66 kV to 132 kV. Uprating the line mast involved removal of all three crosarms and the fitment of long rod polymeric insulators. Support for an earthwire was removed as part of this redesign. The original redesign retained the peak on the line mast (depicted at [EDS]) but all observed line masts have had the peak removed. The EDS website states that “Five masts have been successfully strengthened and converted”; the location of these masts is not known. EDS also designed strengthening for the 10° line mast; observed masts have extra strengthening over that depicted on the EDS drawings.

Two lines use the uprated 132 kV masts. The line from Darlington to Richmond is uprated to 132 kV. Most of the angle towers on this line are of replacement designs (specifically S10 and S60) from Balfour Beatty. One assumes that the Riley and Neate angle masts and towers were demolished and replaced, but this is not confirmed. One angle tower was instead constructed as a truncated L4(m) D30 (carrying a 40° angle), situated where the A1(M) crosses over the River Tees at Cleasby.

A second line, from Newton Aycliffe to Darlington, operates at 33 kV on adapted 132 kV line masts. The original Riley and Neate angle supports have been retained and strenghtened. This is the only line found without the earthwire arms fitted at all; in all other cases, the earthwire arms are present although the earthwire is typically omitted.

Lines

General data

The original Riley and Neate drawings give the following contracts (construction dates unconfirmed):

Existing lines

The following lines are known, all in northeast England:

• Two lines from West Boldon substation to Herrington Burn (Houghton-le-Spring); earthwire absent, and some parts of the line use wood poles
• Herrington Burn (Houghton-le-Spring) to Hawthorn Pit; earthwire absent
• The final portion of Herrington Burn (Houghton-le-Spring) to Peterlee substation uses Riley and Neate supports; this section of line has what may be a fibre optic cable attached to the earthwire
• Hawthorn Pit substation to Peterlee; earthwire absent
• Shotton Colliery to Hartmoor; earthwire fitted
• A short line out of Peterlee has a few Riley and Neate supports; earthwire absent
• Darlington North Substation to Richmond: uprated to 132 kV; replacement S10 and S60 towers
• Newton Aycliffe to Darlington: derated to 33 kV; line towers are of the uprated 132 kV form, while the original angle masts and towers have been strengthened

The line from Shotton Colliery (next to Peterlee) to Hartmoor may originally have extended to Stockton-on-Tees (as H99-11).

Tower forms

The following diagrams are shown to scale at 12 pixels per metre.

H99

The line and 10° masts are unusual in having a rectangular cross section. This may be the reason for Riley and Neate describing them as “masts”. The Balfour Beatty S10 continued this principle. Standard height for the 50° and 60° angle towers is taken to be 40 foot; whether standard height is 40 or 45 foot is unclear. The only complete 50° and 60° tower drawings are for the 45-foot towers, with the shorter bottom panels for the 40-foot towers depicted to the side. Even a 40-foot tower seems taller than expected against the size of the line mast.

The single angle tower crossarm design is covered on a single drawing. Exactly which angle towers this drawing covers is not clear. 72° is certain and 60° is almost certain. There appears to be another angle given that is illegible; this is currently taken to be 50°.

Where the earthwire was on the outside of the deviation angle, the bottom crossarm of the angle towers was reversed.

The angle towers supported suspension insulators, with large brackets supporting the insulator strings on the outside of the angle. This is illustrated below with the 50° type:

No such towers have been found.

Darlington to Richmond

The 132 kV line from Darlington to Richmond uses EDS-designed uprated line masts and Balfour Beatty–designed S10 and S60 angle towers.

The S10 shares the same (approximate) ground-level footprint of the H99 10° mast but the S10 tower is much taller and has greater clearances.

Newton Aycliffe to Darlington

The 33 kV line from Newton Aycliffe to Darlington EDS-designed uprated line masts and strengthened angle supports. Existing 10° masts are to the EDS design but with extra strength. The 50° angle towers are strengthened; details on this change is currently not known.

The 50° type can be seen in both earthwire-inside and earthwire-outside configuration even though no earthwire arms exist.

Tower details

Crossarm width is the total width across the longest crossarm on each side.

Note that Riley and Neate gave the tower heights to the bottom of the top crossarm. The 40-foot line tower is 40′–3″ (not 40′–0″) to the top crossarm but 42′ overall. The 40-foot angle towers are 42′–9″ tall when the top crossarm/peak is taken into account.

† best guesses due to illegible figures on the drawings

Locations

Out of range.