On Fri, 05 Jun 2009 15:04:10 +0100, John Rumm wrote:

I don't know how sophisticated the "anti tamper" is - if its just a 12V
hold off without any clever cable impedance change detection, then it
sounds trivial to defeat.

Decide where you want the new cable to go and install it - leaving ends
close to exiting cable. Strip the outer sheath of the existing cable
adjacent to new cable ends, and join using a suitable terminal box[1].
Repeat at other end, now remove unwanted cable section[2]

Yes that would work but it assumes you know which core does what in the
cable. There is no standard for this and indeed there shouldn't be... A
single installation or one done by the same person/company might be
consistent but that is about as far as it goes.

--
Cheers
Dave.