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Many thanks to Alastair Thomson for permission to publish his notes here.

This article first appeared in the July 2003 edition of Model Rail in the Reader to Reader Q&A section.


How to Scratchbuild your own Overhead Catenary System.

I am indebted to Alastair Thomson for providing me his notes and experiences on constructing the essential of Modern Image Modelling.

Introduction from Alastair:

I built my own 'OO' scale system from scratch using little more than polystyrene 'H' columns and standard electrical cable from a 'DIY' store. Construction was simplified by standardising the design which can accomodate spanning multiple tracks, station platforms and junctions. It is loosely based on ECML which tends to have cables for support in preference to the lattice structures seen elsewhere. Inevitably, there had to be compromises in scaling down to ensure functionality on a small scale, and yet simple enough to be built in a reasonable timescale. Spacing between masts is 40-50cm with curved wires around bends giving a reasonable appearance but still giving the conductor wires enough support and rigidity.

Constructing the Overhead Wire:

Constructing a Single Track Mast:
The Mast itself:

The Arms:

All overall mast heights based on Triang Super 4 track 6mm from base to rail tops.

Mast Arrangement using a Cantilevered Beam in a Station:

Mast Arrangement for Spanning Multiple Tracks:

Terminus/Siding Mast:

Power Feed Mast:

Mast Bases (Common for all mast types):

Arrangement for Crossovers and Points:


  1. Erect all masts and wire supports.
  2. Then put up overhead conductors on main lines. Soldered end joints to be on top conductor.
  3. Start with a curved part of a main line.
  4. Bend the wires to fit between the rails at sleeper level.
  5. Solder together several sections while sitting on the sleepers. Use a bulldog clamp during soldering both to clamp sections together and to act as a heat sink to prevent unwanted melting of existing joints.
  6. Lift the wire up and tack solder to overhead supports. Check alignment with a pantograph loco.
  7. Make any adjustments and complete soldering.
  8. Repeat with straits.
  9. Repeat with any branch lines.
  10. Cut and bend any sections for junctions etc
  11. Solder junction sections to wires already erected.

Materials List:

  •  1.0 mm2 Twin+Earth Single strand cable
  •  1.5 mm2 T+E Single strand cable (Earth usually 1.0mm2)
  •  Single strand 0.5 mm dia telephone cable
  •  6- 9mm hard plywood or sheet plastic
  •  Panel pins
  •  “Plastruct” Polystyrene H section columns 4.8 x 4.8 mm
  •  Polystyrene Microstrip size 2.0 mm x 0.5 mm
  •  Polystyrene cement
  •  Solder


  •  Bases: Matt concrete
  •  Insulators: Gloss brown
  •  Masts and cable supports on single masts: Metallic zinc
  •  Cables: Matt black or leave as bare copper

All the text and images in this article are copyright Alastair Thomson and may not be reproduced without permission.

This page last updated on
8 April, 2014


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