"David Hearn" wrote in message
...
David wrote:
snip
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I would want to know why they replaced 2km of cable rather than
using a couple of splice enclosures and a patch in the cut cable..
The system margin should have been able to cope with this fairly
easily and the material cost would be perhaps £100, add in the
labour and I'd look at less than a grand.

Looks like an excuse to upgrade the link and get somebody else to pay
for it.

Firstly I can only assume the cable must have been near the boundary wall.
I doubt a fibre cable would go through someone's garden. No idea though
how
deep it was buried and how protected it was. Maybe the guy was using a
digger?!?

As for why 2km of cable was replaced - joints in fibre do add losses.
Depending on the length of the cable (in this case, 2km) a joint may have
reduced it to unsatifactory levels. I would have expected a joint to have
been possible - but I've no idea as to the infrastructure in place in that
guy's situation.


In general a system is designed to cope with increased losses of 6dB to
account for aging of components etc. Each splice/joint should add less than
0.1dB excess loss(typically 0.02dB for a decent splice). They would need two
splices to remake the connection, to give a max of 0.2dB excess loss which
should still leave a margin of 5.8dB.

even if the cable had say 100 fibres the cost of connecting them all would
be in the region of 100x2 x £20/splice, to give £4000 + £1000 for
enclosures and other sundries.

depending on the system even upgrading the source/receiver units could be
more economical than relaying the cable

Something is certainly missing from the story... but then again the the guy
who went through the cable must also have been very careless, every cable is
generally enclosed in a green plastic pipe, which should be fairly obvious
at the time.

cheers

David