David wrote:
"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.

Maybe it had been a common problem along the 2km length of fibre. 29 people
before him damaging the cable outside their house such that he was the
unfortunate person who hit the 6db limit...

Certainly glad it wasn't me with the bill though!

D