On Thu, 24 Jun 2010 07:43:08 +0100 someone who may be "Kev Lawrence"
wrote this:-

Is there not a way that a spare core or two of the cable could carry a nice
deterrent voltage to stop this?

If they steal the wrong cable they have to contend with the
signalling supply, up to 650V.

A core of the cable could carry a higher voltage, if the insulation
of all cores is suitable for the higher voltage and this is
maintained throughout the system. However, what would happen to
signalling components if exposed to a higher voltage? Vital
signalling equipment needs to be treated with care if the potential
for a crash is to remain as low as reasonably practical.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000...#pt3-pb3-l1g54