Page 533 - IRSEM_Main Book

22.2.5 The normal height of the contact wire is 5.60 meters at supports. The normal
height of the catenary at its highest point is 7.05 meters. In tunnels as well as
underneath bridges, where clearances are limited, the contact wire may be as
low as 4.58 meters for Broad Gauge and the catenary is also lowered suitably
or terminated at the face of Bridges or Tunnels. The clearance diagrams have,
however, been drawn to suit the extreme positions of the catenary and the
contact wire. In addition, the diagrams make allowances for the stagger as well
as displacement of wires by wind.

22.2.6 Clearances for Safety

In the matter of electrical clearances, the fundamental rule to be observed is
that no one is allowed, under normal conditions, to approach closer than 2
meters from the extreme positions of the live parts of the O.H.E. The following
protective measures shall, therefore, be adopted.

(a) If any portion of a signal post or its fittings where signalling staff have to
work, falls within 2 meters of a 25 KV live conductor, or any metal part
electrically connected to this conductor such portion shall as far as
practicable be protected by an iron screening of approved design solidly
connected to the structural work.

(b) If for any reason it is not practicable to provide the protective iron
screening as mentioned above, a Caution Board of approved design shall
be provided on the signal post at a height of 3 meters above the rail level,
to caution the signal staff.

Note: Technical personnel shall exercise particular care to protect themselves while
working on signal posts not provided with protective screens. If there is any likelihood of
any part of their tools or equipment coming within 2 meter of live equipment, they shall
take a power block as detailed in Chapter VI of the Manual of AC Traction-Volume II
(Part-I). The same precautions are also required in the vicinity of return conductors, which
should be treated as live.

(c) The SSE/JE(Signal) shall explain these instructions to the staff working
under them and ensure that they are correctly complied with.

22.2.7 Drg. Nos. 22-D4 and 22-D5 illustrate the location of signals on the left-hand
side and right hand side of Broad Gauge track and the figures indicate the
minimum heights and distances of Signal from the track to avoid electrical
infringements.

Chapter 22: Requirements Of Signalling in 25 KV AC Electrified Area Page 476 of 535