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by autocracy 2913 days ago
Yeah, you have to remember that in pulse dial days a central office station had a reach of roughly 3 miles. The longer you go, the more you're paying for cable, repeaters, or just losing quality. 90 volt AC for ringing has a limited range!
1 comments
walrus01 2913 days ago
People who've never seen it in person find it amazing that things like 1200 pair phone cables exist... Here's a photo of just a 100-pair:

https://imgur.com/gallery/f1EGp

on this page is a photo of a 1200-pair: http://cityinfrastructure.com/single.php?d=RuralOutsidePlant...

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foobar1962 2913 days ago
How do they colour-code the wires to identify them?

"Ah there's your problem: you've patched the Fire Engine Red pair, it's meant to be the Ferrari Red. Rookie error."

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tmm 2913 days ago
> How do they colour-code the wires to identify them?

It’s actually pretty simple. There are only 10 colors: blue, orange, green, brown, slate, white, red, black, yellow, and violet. They’re grouped in “binders” (using colored strings). You’re likely familiar with the first four pairs from network cables (which omit the white/slate pair). After cylcling through blue through slate paired with white through violet (25 pairs), the wires are bundled with binders starting with blue/white string. That gets you to 625 pairs (the first picture posted above is 600 or 625 pairs). After that, the binder groups are bound in a similar fashion (typically if you’re going beyond 625, the slate/violet binder is omitted to get a nice round 600 in the first group).

Wikipedia has a good article: https://en.m.wikipedia.org/wiki/25-pair_color_code

100-pair cable is only about 3/4” diameter. I have a 24-line 1A2 telephone that uses 75 pairs just to connect to the phone switch and two 100-pair cables feeding a telephone display case in my living room.

It takes me about a half hour to punch down 100 pairs on a 66-block. Old school telecom guys could probably do it in under 10 minutes.

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scoggs 2912 days ago
What about if you are color blind? Change professions?
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walrus01 2912 days ago
Yes. Same problem for fiber fusion splicers. Worked for an ISP that hired a color blind person as a field tech, he didn't last long.
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freeflight 2913 days ago
I'm pretty sure we have Human Rights Conventions to protect people from having to crimp a mess like that.

At least I hope so, if not, then they really should exist.

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