gauge for measuring the diameter of wire
- On electrified lines of the Irish and Northern Irish networks, the IRL1 Irish standard structure gauge and the necessary clearances define the nominal contact wire height.
- The nominal contact wire height may be higher on lines with mixed freight and passenger traffic to permit the operation of trailers with oversize gauge, but the maximum wire height stated in table 4.2.9 shall not be exceeded.
- For electrified lines in Categories II and III, the electrification infrastructure (except for the contact wire and registration arm) shall not enter the gauge envelope defined in the diagram (see Annex F); this is an absolute gauge, and not a reference profile subject to adjustments.
- The nominal wire height adopted in future on upgraded lines in the Great Britain will not be less than 4700 mm. However where constraints require it, the minimum permissible wire height is 4140 mm, sufficient to allow the passage of electric trains built to UK1B gauge.