Milliken T169

Contents

• Overview
  • General data
  • Progress
• Lines
• Tower forms
  • Road crossings
  • Examples
• Tower details

Overview

T169 is a distribution tower type designed by Milliken Brothers for the Antrim Electricity Supply Company.

The drawing schedule seems to contain only a limited number of tower types, chiefly “Double Circuit Tower”, “Double Circuit Strain Tower”, “Single Circuit Tower” and “Single Circuit Strain Tower”. The “strain towers” appear to be standard Milliken 132 kV S30 and D30 angle towers—of the type used by CS PL1—with only the suspension towers being new designs.

Termination at Ballymena substation used what appeared to be a CS PL1 S30 with square-ended crossarms (not an ST), while termination at Poguestown used a D30 (not a DT); both ends of the line are now gone. The old terminal tower at Ballyclare substation—since demolished and now only viewable on Google Street View—is of a strange design. The line is undergrounded through Ballyclare, resurfacing on an “NWE”-style DT just as is found outside Poguestown. The lines from Larne substation to Ballyclare and to Poguestown both terminate on PL16 towers (DT and DT90 respectively).

Based on analysis of drawing number ranges, the “XM” range of LT429 implies a project date of somewhere within 1929. This is consistent with using the CS PL1 towers instead of the revised design, although that might have been simply a case of CS PL1 towers being smaller, and the extra clearances of the revised design not being called for at only 33 kV.

General data

Designed for	Antrim Electricity Supply Company
Design contract	Milliken Brothers T169
Found
Height (straight line tower)
Voltage	33 kV
Dates back to	ca. 1929
Known conductors	Single
Design conductor	?
Circuit count	Single Double
Drawing ranges	T169 / LT429

Progress

Lines

There are three lines in County Antrim that appear to use this tower type:

• Ballymena to a tee at Doagh (outside Ballyclare): single circuit
• Doagh to Larne substation: double circuit
• Larne substation to Poguestown (Larne): double circuit (tower 1 was Poguestown, Larne, now demolished)

Ballymena–Doagh (single circuit) and Doagh–Larne (double circuit) are both route AG.

Tower forms

Northern Ireland Electricity Networks don’t own the drawings of their own towers: these are the property of National Grid, despite Northern Ireland having never been part of the CEB, CEGB or National Grid. As such, no material is expected to be available and they refuse to provide any clues, such as tower heights.

The angle towers appear to be copied straight from CS PL1, but this is not proven; the only new towers in T169 appear to be the suspension towers. These have a rectangular cross section, tapered only on the transverse faces.

With no conceivable access to the dimensions, and not a single sign of a height extension on any tower on any of the lines (although the drawing schedule indicates that height extensions were designed) the suspension towers are drawn to a very roughly estimated crossarm spacing of 6′–9″, a compromise based on vain attempts to size the towers based on what little can be seen of the original porcelain insulators (now mostly if not entirely replaced with polymeric units). This has resulted in differing bottom crossarm heights between the single- and double-circuit suspension towers; matching the ground clearance would mean different crossarm spacing.

The replacement terminal towers appear to be derived from NWE SL4, specifically the metricated SL4(c) from 1996–97. The diagrams below are adapted directly off NWE SL4 D60, as the SL4 DT drawings were never found. The Ballyeaston Road terminal tower in Ballyclare goes back to the earliest Street View coverage from 2008, while the Ballysnod Road example in Larne was erected somewhere between 2011 (prior to undergrounding) and 2022, indicating that the latter tower is almost certainly metric section.

The strain tower diagrams below are to the standard 12 px/m scale if these towers were indeed cloned from CS PL1. The replacement terminal tower diagrams are to scale if those towers were indeed taken or derived from NWE SL4. The suspension tower diagrams are not shown on the line tower comparison page because of the impossibility of determining the sizes.

Single circuit:

Double circuit:

Replacement terminal tower (a) alongside Ballyeaston Road is missing the horizontal ties above the bottom crossarm; (b) alongside Ballysnod Road is also missing the ties above the middle crossarm.

Road crossings

Triangular single-to-double strain plates can be seen on the Strain Towers adjacent to roads, suggesting that the road crossings originally use duplex insulator strings:

The only entries in the drawing schedule are T169-47 “Strain Plates for Duplicate Tension Insulators” and T169-48 “Tension Plates for Duplicate Insulators”, with no mention made anywhere of roads or crossings.

The dimensions of the strain plates relative to the crossarm bars in the diagram above are only very approximate.

Examples

Out of range.

Tower details

No material.