atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring 20-pair cable

I just came across what resembles a standard 25-pair cable, but it only has 20 pairs. The wiring is standard color code, but the pairs stop at yellow/slate. I've never seen this before. Is this simply very old, or just rare? :shrug:

something tells me Ed has it in his warehouse

i have never seen or heard of it...but anything is possible in this business!

The old 1A stuff used 20 pr cable.

Make sure you get a credit from the disributers for the missing 5 pairs.

Probaby an old key system cable made specifically for that type phone system.

How much of this cable do you need, Mike?

Seriously, I have heard of 100 pair cables with five "AMP" connectors (fingers) wired with 20 pairs each. I can't say that I have seen 20 pair cable though. I have seen 18 pair cable and line cords on phones but that's about it.

No Jeff, I only have 8, 12, 16, 25, 50, 75 and 100 pair cable in "the warehouse". 20 pair is a stumper to me.

The tie cables that our local Bell monopoly uses to connect our collocated equipment to the frame is a 262A cable with 5 20-pair binder groups. I asked the oldest person I could find why it was 20 pairs but he didn't know. :-)
They still use it and install it, some of the cable was just placed for me.

8 and 16 pair cable? What for?

I stumbled across it while removing some old, unused horizontal blocks. The cable was still wired down to the backside of the block, but the other end was cut and buried with the other cables. I was told that the block was used for an old alarm circuit tie cable. It certainly stopped me in my tracks.

I supply 800AS 20PR 26AWG as well as 1249C 20PR 26AWG cable to Lucent. Both are shielded.

Jeff:

We use 8 and 16 pair for tie cables where 25 is too much.

The 5 x 20 pair cables (100 pr) were used for the old 30 button call directors that had 5 vertical rows of 6 lines each. One binder per amphenol. Because the violets were spare in each finger, Bell saved money on the cable.

Had a similar discussion on this about a year ago. The only difference was it was a 32-pair cable. Also a point of interest was the 32-pair cable was part of military inventory. The reason I mention that is if I remember correctly Mike, you are a civilian contractor working on a military facilities.

John, Thanks for sharing that! I found the 32-pair cable thread that you mentioned. You guys beat that topic into submission. I'm so glad you decided to let everyone live to see another day! :rofl: (BTW, not a contractor, I'm Civil Service.) Thanks for mentioning the older thread; I've personally never seen the 32-pair cable.