Telco line question

If anyone is familiar with telco construction practices, maybe they can answer this one.
The local telco was installing a brand new overhead line from the
central office near me a few months ago. I stopped by and asked one of the linemen what kind of cable they were stringing and he told me it was thousand pair, 26 gauge (why they are still using such old technology is a topic for another post). Later, I noticed that every few blocks, where they had to tie into an underground lateral, they would route the cable down a pole, into a splice cabinet and then back up the pole to continue on. When transitioning from the overhead line to the riser on the pole, they installed a splice box on the overhead line and then run a separate section of cable down the riser, through some conduit and into the cabinet. The downstream circuit goes back up the pole and into another overhead splice. As far as I can tell, all of the pairs are spliced and routed through the underground section. There are only two cables in and out of the overhead splices, so I assume that they aren't splitting a subset of the cable pairs out and running it to the cabinet.
My question is: Why can't the overhead cable be routed through the short sections of conduit and into the splice cabinet? It appears that the labor to make up each overhead splice is about a week for one person, which is not cheap. Its probably more expensive to make the overhead splices (working up a pole) than it is to work in a ground level cabinet (not a vault, just a pedestal style cabinet).
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"Paul Hovnanian P.E." wrote:

Are you sure they have to splice every pair overhead? I've seen where they drop X number of pairs to the pedestal and leave the other pairs alone in the splice housing. A housing to splice 1000 pairs would be quite large and heavy.
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You probably *should* make another post. What is it about 26 gauge copper cable that you think inappropriate today?

That is unlikely, though with a 1000 pair cable it might be. Probably some suitable subset of the total actually break out at the junction box, even if they all do go down the pole. It is also likely that the cabinet at the bottom of the pole contains a variety of equipment, in addition to a junction box. There could be loading coils, T1 repeaters, cable carrier, or even an entire remote switching unit.

But even if there is no cable between two overhead splice boxes (in which case clearly all pairs do go to the cabinet below) that would not necessarily mean that all pairs are broken out and made available in side the cabinet.

The overhead cable and the cable going down the pole are of different physical construction. I doubt the overhead cable can be bent into a tight enough curve to bring it down the pole.
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Floyd L. Davidson <http://web.newsguy.com/floyd_davidson
Ukpeagvik (Barrow, Alaska) snipped-for-privacy@barrow.com
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"Floyd L. Davidson" wrote:

Good question. I'm not familiar with the state of the art, but some other companies are going 100% fiber for new installations to within a few thousand feet of their customers. This is a 5 mile circuit from the CO.

Actually, I got a peek inside one. No such equipment, Just terminal blocks.

True. But they did terminate everything running into the splice box from the overhead cable. They may have run a smaller group down the pole into the cabinet and left some pairs unused, but eventually they will have to make up some more splices overhead or the cable's capacity can't be used.

They can turn some pretty tight corners with the overhead cable. In fact the underground cable looks like it doesn't bend as well.
I used to work for a local power company and some of the stuff we pulled through vaults and up risers didn't bend very well. You just use larger radius conduit.
Also, the economics of installing utilities is such that labor is most of the cost, not the materials. I'd think one would spend more on the equipment if one can save a few thousand splices.

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wrote:

was
is
continue
separate
they could be getting ready to roll out DSL. this requires a DSLAM every 15,000 ft (to subscriber)
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Fiber is fine between telco facilities, but is not viable for customer loops. Or, it is not viable without also having some form of copper along with it, to supply emergency power. As a result you'll see a great deal of long haul fiber, but most local outside plant is still going to be copper for quite some time into the future for residential areas, and much so even for local distribution in business areas.
We might note too that the state of the art with 26 gauge cable is vastly different than it was say 3 decades ago. Both the cable itself (which once used paper insulation and now uses plastics) and the equipment directly connected to it are modern technology.

Was that after the project was completed? If so, that explains even more about why it is copper. This must be a feeder line, from which a number of other cables cross connect to route to individual drop locations??? Hence, with a 1000 pair cable there might be something like 10 of these junction boxes, each with perhaps 200 pairs (some of which show up at other junction boxes too). (Given your later comment about "underground cable", this probably feeds a network of buried cables that go down individual streets to homes?

I'm not getting a clear enough picture yet of what you are seeing to be sure what it is. If there are one or two splice boxes on the pole, and there is a cable between them, then you can be fairly certain that not all of the pairs appear at the junction box in the cabinet at the bottom of the pole. That's pretty much standard procedure. But even if they ran the whole 1000 pairs down the pole and back up, I doubt they would want to put 1000 terminals in at each pole rather than just splice 8 or 9 hundred of them. Usually the splicing would be done on the pole, not in the cabinet though.

Underground cable? I'm confused about what is there. Aerial cable and underground cable are indeed going to be different things, as is the cable coming down the side of the pole to the cabinet.

I was assuming that whatever comes down the pole necessarily has some tight bends in it.

Depends on what part of the country.
With a feeder cable distributing to multiple end runs, they want to install it with maximum flexibility to avoid having to install more new cable in the future.
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Floyd L. Davidson <http://web.newsguy.com/floyd_davidson
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"Floyd L. Davidson" wrote:

I don't think we'll be seeing fiber subscriber loops for quite some time. But I'd expect a more rapid migration to digital (either copper or fiber) feeders up to some local cabinets where the conversion is done.
The local cable TV company is pretty sucessful at maintaining their CATV and digital telephone services with pole mounted battery packs every few thousand feet.

Its possible that the telco wants to stick with copper and go with some sort of high bandwidth over copper technology. In the future, that is.

Yes. Every few blocks, this feeder dips underground to a splice cabinet and then goes back overhead again. All of the neighborhoods have underground wiring. When I peeked into an open cabinet one day, there appeared to be 4 or 5 cables entering it. Other then the two risers, these go into the local neighborhoods.

No. That's the point. There is no cable between the OH boxes. They appear to transition the overhead cable into an underground drop into a splice cabinet.

Then, I'd expect to see a single OH splice box and a single riser from the pad mounted cabinet. That would still save them one set of overhead splices compared to what they have now.

This is how it is set up (view with fixed font):
oh splice oh splice from CO +---+ +---+ to next riser >-------- oh cable -----+ +-+ +-+ +----- oh cable ------> +---+ | | +---+ | | | | | | +---------+ cable risers in conduit(2) ->| | | | padmound cabinet | | | | | | ++---+---++ | | | | | | +------+ | | +--------------+ V ug laterals
The major question I have is why they can't eliminate the two OH splice boxes and just run the overhead cable down through the conduit runs into the cabinet. Then, make up whatever splices in there just once.

No tighter than a bend in the overhead line turning a corner in mid span.

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The method our teleco has been using for the last several years, is fiber to the neighborhood. They set up a medium sized (appears to usually be either a single or double 4') padmount box near the neighborhood, and run fiber to it from the main switch building. From there throughout some set radial distance, it is copper wire. All runs between main switch buildings are ug fiber, and have been for many years. They are actively replacing long copper runs with the fiber/box set up all over the area. This teleco does offer DSL, and this seems to play into the design of the system.
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Anthony

You can't 'idiot proof' anything....every time you try, they just make
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I went on a tour of NJ Bell a little over 30 years ago. This was a week long effort to let us know what the "real world" was like.
Anyway, the technology was fairly mature by then. The "new" cables had plastic insulation rather than paper and the various "splice" gadgets were in common use. Bell Labs had computer programs to simulate these wires so that the operation of special circuits could be predicted. While I'm sure there was some room for progress I doubt that someone who went to sleep 30 years ago would be very surprised by the copper wire part of the "outside plant" today.
The Bell System liked to have as much of the equipment safely in climate controlled buildings rather than in boxes on the ground or on poles or in the customers' buildings. It's just easier to maintain (and power) stuff in the central office than out in the middle of nowhere.
Back then, the cost of your basic POTS wire was on the order of $50/pair/mile. (That's everything: cable, splices, poles, whatever.) Even in you factor in inflation, that's low enough to want to keep the fancy stuff in the CO as much as possible.
Beyond some point, of course, they have to install equipment outside of a CO (or "wire center"). But copper wire is plenty good for most customers.

"Modern," as in less than 40 years old, maybe.
"Modern," as in less than 5 years old, I don't think so.

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snipped-for-privacy@crosslink.net (John Gilmer) wrote in

It is possible that the system spec's, or whatever VZ is using today in place of the old BSPs, say that for underground applications jelly filled cable must be used, thus the necessity of a splice at each riser. As to 26 Ga copper being "old", it depends on the application. In short distance, urban applications, it is probably as viable both technically and economically as fiber. Fiber to the premise, using passive optical networks, is beginning to be deployed in the local loop more and more. Subscriber interfaces with battery backup are approaching the reliability of wireless, but have a long way to go before matching copper. That being said, there are continuing breakthroughs both in batterey technology and circuit design that will extend the battery life and eventually approach copper reliability. I don't think it's going to be long before customers and regulators begin to accept a trade-off of bandwidth for emergency availability.
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One of the interesting things I leaned on my tour 30 years ago was that the "jelly" stuff was introduced because when the plastic insulation got wet the water would travel up and down the cable and "find" every pin hole in your 1000 pair (or whatever) cable until the next splice. The old paper insulation would swell and confine the damage to a short section. With "luck" and some dry nitrogen the cable might be kept in service. The original jelly was some stuff that resisted most normal solvents so it was a messy PITA to splice. That definitely would be an area where one would home some improvements have been made.

and
long
Maybe. But I always keep one "low tech" telephone about just in case the power fails.
There's a guy who works for the telephone company in one of the churches we go to. Next time I see him I will try to pump him for information. He may just know enough to do his job and nothing else, however.
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Tom Lager wrote:

I was at Bell Labs in 1949. We sent base-band video, (B&W), over 26 GA copper all over Manhattan. It did require a bit of "equalization".
Later, at Holmdel, I worked on "guided wave" technology. The idea was to use a TE01 waveguide to achieve large bandwidths. The "optical waveguide" has proved much more practical.
Without fiber to the premise, a lot more can be done with copper. A simple example with large economic pay-back, is to replace manual electrical, water, and gas meter reading with data sent back on the existing premise wiring. This requires no technological break-through, but does involve mundane things like company structure and unions objection.
Moving away from base-band signaling has probably saved more POTS bandwith than anything else, independant of the transmission medium.
One thing seems to be certain: The use of bandwidth will rise to meet its availability, even though we may not now even know its uses! AT&T thought they could sell "picturephones" using the new bandwidth.
--
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My, my!
I spent the winter of 1973/74 at Holmdel.
That was around the time it finally sunk in that AT&T had wasted HUNDREDS (in 1960s $dollars) of $millions lars trying to make "PicturePhone" work on your POTS wires.

objection.
Well, there are two generations of technology beyond that.
First generation required the meter reader to "wave a wand or point a LED gadget toward the meter. The second generation just requires the meter reader to just drive about the neighborhood. In the case of the water meter, I think it requires that the batteries be replaced every few years. I suppose that the next "breakthrough" would have the batteries be charged by the water flow.

As mentioned, "Picturephone was one of the two or three BIG mistakes taken by AT&T management.
(In case you wonder, the 2nd was the decision to get out of "military work" a few years before RR was elected.)
The 3rd was the decision to overspend on fiber and cell phones and other "broad band" nonsense. AT&T had a REVERSE SPLIT to keep its stock listed on the Big Board.
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Wow, you became an expert of "modern" telecommunications in 1 day over 30 years ago. Impressive.

Actually, it had just started. Today it is fairly mature.

The point that needs to be made is than in 1975 there was still a great deal of paper insulated lead sheathed cable in use. However, by then I don't think anyone was still installing anything but "modern" cable plant.
The difference is that today those old cables have virtually all been replaced for a variety of reasons, with maintenance cost and poor performance being the two major causes.

Rip VanTelecom would not be surprised at the cable plant, where incremental improvements are not likely to be visible improvements (better materials that look almost identical or at least do not have obvious differences). But the way it is used would be an absolute shocker. *Nobody* (except perhaps Vint Cerf and Bob Khan et al) expected anything like what has happened. In fact, the Telecom Industry were the last techie types to actually get a clue about what was happening when it did!

It was then, but it isn't now. The computerization of telephone switching changed that. The cost of a software load for a major switching unit is upwards of a million dollars, and typically requires replacement every three years at a minimum. That has made the proliferation of CO switches very expensive compared to the use of Remote Units to increase switching capacity.
And shortly after that mindset changed the topology of a telco's network, the need for higher bandwidth to many more subscriber locations became a driving force which caused even greater dispersal of equipment into the field as opposed to a Central Office. Subscriber Line Carrier units became the norm rather than a rare adjunct.

Depends on where your "most customers" are and what they want to do. It makes no sense whatever to run copper pairs to an industrial complex, as one example. It probably makes no sense to run fiber in a sprawling and sparsely packed suburb either.

For cable plant, anything 5 years old is experimental. The "Modern" age for cable did indeed begin about 40 years ago. Meaning that a plastic cable installed in 1965 is *not* going to be replaced for purely technical reasons (while a PAP cable installed in 1955 will almost certainly be replaced just to have a better cable).
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Ukpeagvik (Barrow, Alaska) snipped-for-privacy@barrow.com
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