eircom and Pressurised Fibre Ducts?

yuloni

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rugrat69

Normally an Otdr is used to pin point an exact break in the fibre cable if the cable is cut etc. More than likely they may have been blowing fibre in the ducts.
Although having said that I have not heard of eircom blowing fibres they normally just run in standard bulk cable.

FSL

A break in the ducting does not necessarily mean a break in the cable. If the detection of a break in the duct meant it could be rectified before any damage was done to the cable it could be a quite cost effective system.

swampgas

Pressurised ducting was (is?) also used to prevent water leaking in and damaging the cables.

See this reference for example

yuloni

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yuloni

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swampgas

Nope - the duct is pressurised, to keep it water free. That keeps the cables dry. Obviously fiber isn't affected by water ingress as much as older twisted pair copper, but AFAIK the cables themselves are not pressurised.

* Edit* the link I gave was not the best example of duct pressurization!

yuloni

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arctan

fibre subducts arent pressurised ... they would be sealed, but not pressurised ...

pressurisation happens on the copper cables from exchange to exchange, and exchange to local cabinet ....

the reason is to prevent cable damage from water ingress and as a system to notify when cable breakdowns occur .... along the course of the pressurised cable ducts are transducers, so when pressure drops below a certain level and alarm is set off in the monitoring centre and a investigation team sent out.....

fibre usually has a loop back to the monitoring centre and when a link goes down, the loop back is broken, hence triggering alarms

yuloni

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arctan

yes its a fairly labour intensive process with lots of epoxy resin ...
cant remember the figures off hand, but its not always constant, there'll always be losses and the compressors in the exchange work all the time and trigger when the pressure drops too low to top up the pipe

10belowzero

All main cable distribution across the network , are pressurised and monitored.
The individual cable's are pressurised , not the duct's that carry the cable, as it would be next to near impossible to maintain air / water seal integrity due to subsidence , vermin , creepage , etc ,except outside of the most controlled environments.
Every exch + main dist cable is monitored , which in it's self is a vast internal network within eircom , which is monitored nationally 24/7 - 365 .
Half of our time is taken up opening up and resealing air tight cables , pressure testing , recording etc .

mk6705

arctan wrote: »

fibre subducts arent pressurised ... they would be sealed, but not pressurised ...

pressurisation happens on the copper cables from exchange to exchange, and exchange to local cabinet ....

the reason is to prevent cable damage from water ingress and as a system to notify when cable breakdowns occur .... along the course of the pressurised cable ducts are transducers, so when pressure drops below a certain level and alarm is set off in the monitoring centre and a investigation team sent out.....

fibre usually has a loop back to the monitoring centre and when a link goes down, the loop back is broken, hence triggering alarms

Exchange to exchange cables are either:
- Coaxial cable (Which it is possible some of which may be copper)
- Radio linked (By point-to-point microwaves) or
- (In the vast majority of cases) fibre.

Not copper cables.

Solair

Trunk cabling between exchanges in this day and age is more than likely all fibre.

Pressurised cables would mostly carry bundles of individual copper lines to cabinets / junctions and out to end users, not fibres between exchanges.

Those copper bundles are extremely sensitive to water ingress, which is why they go to such lengths to ensure they're kept dry..

Copper reacts with water (i.e. rusts), so if the cables get wet, it would be an absolute disaster and you'd have to replace large lengths of expensive cable that carries hundreds of individual lines.

When they were used for trunk lines (between exchanges) faults, crossed lines, poor signal quality etc etc were very common.

Fibre to cabinet is probably a lot easier to install, handle and work with than heavy copper cables and it is far less likely to be damaged by normal environmental conditions as it's just a bundle of insulated glass fibers (usually only a few of them).

It's much thinner, it's more flexible, does not require shielding from RF, electric cabling or anything else and not damaged by water.

So, if anything rolling out fibre down existing ducts that are carrying huge thick bundles of individual lines should be really easy and actually reduce installation problems and maintenance.

Also, with copper prices as high as they are, I would imagine a run of fibre might be much cheaper (it's only silicone!)

The only issue fibre really has is if someone digs it up / cuts the cable.