From: stephen@sprunk.org
On 07-Jul-14 14:36, Robert Heller wrote:
> At Mon, 07 Jul 2014 11:07:21 -0500 Stephen Sprunk
> wrote:
>> On 07-Jul-14 08:05, Adam H. Kerman wrote:
>>> hancock4@bbs.cpcn.com wrote:
>>>> When say the "copper is worn out", do you actually mean the
>>>> insulation of each wire and the sheath of the cable itself? I
>>>> would think the copper itself doesn't wear.
>>>
>>> Huh? Copper can oxidize, like any other metal.
>>
>> Yes, but like aluminum oxide, copper oxide forms a protective layer
>> that protects against further oxidation. It's not like iron
>> oxide.
>
> I believe that copper is non-conductive. And the phone wires are
> actually copper plated steel (for strength).
Maybe long ago or in special applications, but all the stuff I've ever
seen is solid or stranded copper, no steel. Phone wires don't _need_
strength; they need flexibility and conductivity, both of which pure
copper does a far better job of than steel.
> Plus as the cables move in the wind and the shething rubs against
> the copper wires, the copper oxide layer is rubbed off, exposing
> fresh copper.
There is no rubbing of anything against the copper itself, just one
piece of insulation against another. Oxidation only happens at the very
ends where the insulation is stripped to make connections, and strain
relief is used in those locations for exactly that reason.
>> Of course. One of the things the insulation is protecting against
>> is air, which contains water (among other things).
>
> And the *insulation* breaks down over time and exposure to UV rays.
The insulation on the wires is not exposed to UV rays; only the sheath
is, and modern materials are designed for UV resistance. Yes, the old
stuff had problems, but that's why better materials were developed
decades ago.
> And it too has fatigue issues (moving in the wind, etc.).
The entire cable sways, but the stress on the individual wires is
negligible because they're suspended from a steel carrier.
> Note: I am NOT saying the fiber optic cable will last longer than
> copper cable -- both have fixed lifetimes -- just that the cables
> (copper) that are *now* on the poles in Western Mass are generally
> near, at, or past their intended lifetimes, since *Verizon* has not
> bothered to do the needed maintaince (eg replace them in a timely
> manor).
That's entirely possible; nothing lasts forever, and that area would
have some of the oldest wires in the country.
> At this point it is not really a matter of whether to replace
> them or not, but what to replace them with: new copper or new fiber
> and what really makes more sense in the long term. Given that in time
> (10 years? 20 years? 30 years?) there will likely be need for more
> bandwidth than copper can ever handle, it makes little sense to put
> up *new* copper and then tear it down well before it wears out. We
> might as well future-proof ourselves and put up fiber. We may not
> need the bandwidth *now*, but in the future we will, and probably not
> in all that distant a future.
OTOH, the labor and equipment to terminate fiber is more expensive,
which is why every other telco in the country is doing FTTN.
The last few hundred feet from the SLC to the home don't gain anything
from fiber; copper works just fine for such distances, and already has
100+ times the capacity of what is needed today. If fiber is eventually
needed for those runs in the far future, for some reason, they're
relatively easy to replace.
The trunk lines are the real problem, and those _are_ being replaced
with fiber everywhere, whether FTTN or FTTH.
S
--
Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking
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