Testing old POTS cables

I've got a three story office building circa 1984 with tons of old phone stuff everywhere. Each floor has around a dozen 66 blocks and of course a mess of tangled phone cables going everywhere. Currently only 1 floor has tenants and pretty much everything else can go. I have a feeling most if not all of these remaining tenants aren't on this old crap, but ya never know. I'd like to get rid of as much of this as possible. I would like to have the owner bring in a phone contractor to identify and demo this stuff, but from past experience, I know that he won't. So to cut down on everyone's frustration for eternity, I'm going to spend some time on this. I am familiar with 66 blocks and testing for active lines with a handset or voltage, but:
Questions:

1. Could someone be getting DSL thru this maze of 66 blocks? How do I test for that? Does it show 50 vdc like POTS?

2. What about something like a T1 line?

3. Any other tips and tricks?
 

fishin' electrician

Senior Member
Location
Connecticut
I would like to have the owner bring in a phone contractor to identify and demo this stuff, but from past experience, I know that he won't. So to cut down on everyone's frustration for eternity, I'm going to spend some time on this

3. Any other tips and tricks?
Yes, before you jump in, just remember, 'no good deed goes unpunished' is never truer than in the electrical trade.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
T1 on a two pair line.
Usually white/blue, white/orange
DSL can also be on a 66 block
Dry loops (DSL with no voice) will have no voltage
You could get lucky and it’s tagged.
 

paulengr

Senior Member
A lineman’s handset can instantly detected all of these. If you hear computer tones/noise it is DSL or T1. If dial tone voice line. Simple.

If it’s an office and comes down to repair often cheaper to just pull a CAT 5E and/or upgrade to IP Phones or voice gateways. Most of that phone line went in during the 1960s and it’s pretty rotted out.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Wow! You are lucky.
"while I'm here, I'll take a minute to fix this also" has bitten me more than once.
 
Unless there's a huge reason to demo, leave it alone! In general, the cable and 66 blocks don't "go bad". If you know most of it is out of service, just pull the cross-connect wires and stop there.
Can you give me quick primer here? Im not clear on how these things are structured. Are the cross connect wires the ones that go to the other 66 blocks? I know that on the split blocks, its somewhat easy to identify the unactive lines because of the jumpers, but if they are solid blocks that method wont work.
 
Start looking at whether wires/cables punch to the outer or inner row of a block. The more permanent stuff will be cables on an outer row. The permanent cables will (usually) be 2-/3-/4-/25-pair jackets coming up under each block and fully-terminated.

Cross-connect wires are just that, they cross/patch from one block to another; they're temporary for the life of the circuit. Usually yellow/blue or white/blue. Hardly ever removed, sigh, the telco certainly doesn't when service is stopped, they just do that at the central office. Heck, most of the time they abandon the equipment since it's not worth the trouble to come out and remove.

Almost anything punched to an inner row is circuit-specific an for a vacant space is probably out of service.

Non-critical voice circuits are almost never tagged; specials like an elevator phone or FA line might be tagged. There's a thing called Special Service Protection (SSP) which put little red bumpers on the 66-block terminals but those almost always remain after the line is shut off.

If I can ID the cables going into a vacant office suite or vacant floor, and am fairly sure that there aren't any lines for elevator/FA/etc, I'd be inclined to pull all the cross-connects (but then I've been working with this stuff since pre-divestiture :LOL: so have an eye for things).
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
I wouldn't touch it! And I know what I'm doing, I AM a phone contractor. All you need is some business coming after you because you killed their internet or phones and they are out of business because of you. Hope you have deep pockets. You also don't know what is used for alarms, elevators, DSL, T1, etc. It's not unusual for lines that have been disconnected to still have battery and even dial tone. It's not unusual for DSL lines to not have anything on them.

Bottom line is that unless the building is completely vacant don't do it!

I once was in a similar situation. New tenant wanted me to get all that unused cabling out of his ceiling. There was at least a 6" bundle running through the space. I told him I don't want the liability and handed him my Sawzall. Here, have at it...

-Hal
 
There is one rule of phone wiring. Do not cut anything that you don't have both ends of.
Oops, violated that one with a few hundred pairs😶.

I think all is good. There are only 5 or 6 tenants left in the building, and the owner wants them out ( of course im not saying I'll happily sabotage their phone service, but keeping them happy isn't part of the equation). If we do take someone out then we'll get a phone contractor in their to fix it.

By the way, this is kinda cool. I went to www.scout.tel and you can enter a phone number and it tells you, among other things, who the provider is. There seems to be only one tenant who is on the POTS provider, and I called them and heard their phone ring.
 

DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
FWIW, I'd never remove properly-installed closet-to-closet 25-pair cables, only unused ones into an office suite- too many times I've needed a few pairs from here to there and the old cable was gone.
Like those old centronics blocks

Sent from my BE2028 using Tapatalk
 

grich

Senior Member
Location
MP89.5, Mason City Subdivision
Occupation
Broadcast Engineer
FWIW, I'd never remove properly-installed closet-to-closet 25-pair cables, only unused ones into an office suite- too many times I've needed a few pairs from here to there and the old cable was gone.
You just never know. Ten years ago I'm putting a small radio station into a 50-year-old former S&L. Marble floors over hollow core concrete slabs. There was a 25-pair cable into what was to be the studio, coming out of a tombstone by the exterior wall. It had an AMP connector on it. The circuit needed to be on the other side of the room so I used a 25-pair extension around the room ending in a "harmonica" (AMP connector to multiple RJ12 jacks). I needed four POTS lines, a fifth jack for a Partner extension line, and a pair for a Startech ethernet extender (basically a short-haul DSL circuit) to a basement office. I started toning out pairs, and after the fourth pair, things stopped lining up. We finally found the 25-pair cable didn't home-run to the phone room, but to a bunch of blocks in a closet, where not everything was cross-connected pair-to-pair.

We had to use the 25-pair cables because the landlord didn't want us drilling the floors and trying to fish our own cable due to asbestos concerns.
 
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