4 ms·

I think this is common in places where they don't expect moisture to reach, but then things change and it gets there anyway. If your POTS lines are down and th

I think this is common in places where they don't expect moisture to reach, but then things change and it gets there anyway. If your POTS lines are down and the telecom company is telling you a "wet pulp repair" is underway, your phones are going to be down for a while because a bunch of paper-insulated cables need to be manually rewired because they got wet and corroded. I found this interesting: http://etler.com/docs/bsp-archive/629/629-295-300_I3.pdf http://etler.com/docs/bsp-archive/629/629-295-300_I3.pdf - guess it's standard practice to dry out the lines, wrap in cloth, put dessicant and then seal it.

deleted 5y ago
[deleted]
jcims 5y ago
I know there are some telecom folks on here that may be provoked to correct me but pulp was standard before the advent of cheap plastic insulation in the 1950s on up. I live in the midwest and my brother is a lineman for AT&T. There is an astonishing amount of pulp-insulated phone line still in service today. In order to keep it dry, the conduit that the pulp lines are run through is pressurized to 5-10psi. Anyone that has worked with air compressors knows that pumping ambient pressurized air down into underground pipes is a recipe for condensation, so high capacity air driers are required to remove the water before it goes underground. Any kind of outage on the compressor or dryer is effectively an emergency because water infiltration can happen almost immediately, creating an outage and extremely expensive repair.
- ComputerGuru 5y ago
  > I know there are some telecom folks on here that may be provoked to correct me Aka Cunningham’s law > Any kind of outage on the compressor or dryer I’m confused: isn’t a bigger concern any physical damage to the conduit anywhere in the run that is too large for the compressor to overcome? Or are we talking football-field-sized compressors here?
  - BoorishBears 5y ago
    http://www.airtalk.com/z_ref-4_1.html http://www.airtalk.com/z_ref-4_1.html
  - Johnythree 5y ago
    The gas flow on each line was monitored with flow gauges, so any increase could be attended to before it became a problem.
- stefan_ 5y ago
  The more you learn about this ancient cable technology the more absurd it becomes. We shower these fuckers with money but they would rather keep their paper insulated phone lines with permanent compressors and dryer running than braindead simple fiber. No wonder it is permanently broken and they can't keep a single 9 of reliability.
  - jcims 5y ago
    I would bet this is a capex/opex thing.
  - oasisbob 5y ago
    Fiber may be simple, but the way we use it is not. Unlike copper, a GPON fiber install is going to have active electronics and splice trays for every several dozen subscribers. Plenty of opportunities for water ingress to still cause problems.
    - namibj 5y ago
      Don't go for GPON, if you have a chance. Direct cabinet-to-apartment single-mode fiber (can be a pair that gets BiDi optics if one of the fibers fails, though only worth it if correlated failures aren't the bulk of issues) is future-proof. Also GPON tends to not get anywhere near the awesome pings 1G-LR and 10G-LR provide in sub-lightpseed regional situations.
    - kazen44 5y ago
      Also, sending a singal across fiber is definitely not easy. ADSL is basically modulating a radio wave over a cable directly to another device. Fiber requires high quality optics, high quality lasers, tons of active hardware if you want to do it at scale. (not to mention the mind boggling physics and manufacturing required for things like DWDM, optical path switching etc). Fiber optics have existed since the 80's yes, but prices of high quality fiber solutions have only dropped massively in the last decade or so.
      - stefan_ 5y ago
- djweis 5y ago
  There is still a lot of it in service. Sometimes you'll see a tank of nitrogen chained to a pole. It is there to put pressure through the cable to keep water out of a cut/nick on the lead sheath. The lines are pressurized normally from the central office and if the monitoring shows a drop in pressure (a cut in the sheath), they roll out cable maintenance.

deleted 5y ago

[deleted]

jcims 5y ago

I know there are some telecom folks on here that may be provoked to correct me but pulp was standard before the advent of cheap plastic insulation in the 1950s on up. I live in the midwest and my brother is a lineman for AT&T. There is an astonishing amount of pulp-insulated phone line still in service today. In order to keep it dry, the conduit that the pulp lines are run through is pressurized to 5-10psi. Anyone that has worked with air compressors knows that pumping ambient pressurized air down into underground pipes is a recipe for condensation, so high capacity air driers are required to remove the water before it goes underground. Any kind of outage on the compressor or dryer is effectively an emergency because water infiltration can happen almost immediately, creating an outage and extremely expensive repair.

ComputerGuru 5y ago
> I know there are some telecom folks on here that may be provoked to correct me Aka Cunningham’s law > Any kind of outage on the compressor or dryer I’m confused: isn’t a bigger concern any physical damage to the conduit anywhere in the run that is too large for the compressor to overcome? Or are we talking football-field-sized compressors here?
- BoorishBears 5y ago
  http://www.airtalk.com/z_ref-4_1.html http://www.airtalk.com/z_ref-4_1.html
- Johnythree 5y ago
  The gas flow on each line was monitored with flow gauges, so any increase could be attended to before it became a problem.
stefan_ 5y ago
The more you learn about this ancient cable technology the more absurd it becomes. We shower these fuckers with money but they would rather keep their paper insulated phone lines with permanent compressors and dryer running than braindead simple fiber. No wonder it is permanently broken and they can't keep a single 9 of reliability.
- jcims 5y ago
  I would bet this is a capex/opex thing.
- oasisbob 5y ago
  Fiber may be simple, but the way we use it is not. Unlike copper, a GPON fiber install is going to have active electronics and splice trays for every several dozen subscribers. Plenty of opportunities for water ingress to still cause problems.
  - namibj 5y ago
    Don't go for GPON, if you have a chance. Direct cabinet-to-apartment single-mode fiber (can be a pair that gets BiDi optics if one of the fibers fails, though only worth it if correlated failures aren't the bulk of issues) is future-proof. Also GPON tends to not get anywhere near the awesome pings 1G-LR and 10G-LR provide in sub-lightpseed regional situations.
  - kazen44 5y ago
    Also, sending a singal across fiber is definitely not easy. ADSL is basically modulating a radio wave over a cable directly to another device. Fiber requires high quality optics, high quality lasers, tons of active hardware if you want to do it at scale. (not to mention the mind boggling physics and manufacturing required for things like DWDM, optical path switching etc). Fiber optics have existed since the 80's yes, but prices of high quality fiber solutions have only dropped massively in the last decade or so.
    - stefan_ 5y ago
djweis 5y ago
There is still a lot of it in service. Sometimes you'll see a tank of nitrogen chained to a pole. It is there to put pressure through the cable to keep water out of a cut/nick on the lead sheath. The lines are pressurized normally from the central office and if the monitoring shows a drop in pressure (a cut in the sheath), they roll out cable maintenance.