Telegraph poles

Telegraph poles are used to carry wires supporting:

• telegraph circuits
• telephone circuits
• signalling circuits of many kinds.
• electric power circuits

Construction

Telegraphs poles were originally made from straight tree trunks about 20 metres long. The part of the pole in the ground is often treated against rotting with creosote, etc.

Poles are fitted with crossarms which may have 2, 4 or 8 insulators made of porcelain that support the wires.

The wires are typically copper or galvanised iron, the choice being determines by the electrical resistance that can be tolerated. The wires are not normally insulated, as they are far enough apart so as to prevent short circuits.

The pole is fitted with stirrups that allow the electrician to climb the pole for the purpose of maintaining the wires.

The terminal poles are fitted with braces (aka stays), which enables the wires to be put under tension, which reduces the tendency to sway and touch, touching causing undesirable short circuits.

Metal braces, both 0 degree and 45 degree, are fitted to the crossarms, so that these crossarms do not sag to improper angles, which may cause wires to short circuit.

The highest voltage of any wires carried on telegraph poles is probably about 120V.

Electricity poles

Electricity poles carry a small number of wires, which are more widely spaced because of the much higher voltages involved. The insulators on higher voltage electricity circuits tend to have several segments, rather like an acordian.

Gallery

• Telegraph poles
• 
  Pole at near Bron Madog
  Appears to have 3 crossarms.
• 
  Telegraph pole.
  A few unused J-insulators for terminating wires.
  Stirrups underneath.
  0deg and 45deg braces.
• 
  Blank
• 
  High Voltage electricity pole,
  with lightning arrester wire on top.
• 
  Image: Telegraph pole with 3 crossarms of 4 wires (zoom)
  (yellow arrow)
• 
  (green) Brace
  (red) J-insulator
  (purple) tap-off wires
  (yellow) Climbing stirrups.
• 
  Blank
• 
  Electricity pole with lightning arrestor wire on top.
• 
  David Lloyd George heading an up train through Boston Lodge Halt

See also

• S&T reference folder 1969 - many sources including plans of typical telegraph poles.