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We just moved into a home that has a renovated basement and all of the receptacles have two CAT5 wires pulled to them (one for telephone and one for data) but none of the wires are labeled or terminated in RJ45 or RJ11 jacks. How do I test the wires to tell if they have data or phone signals?

  • Do all the cables go to a central closet or panel? how are they connected in there? – diceless Feb 4 '15 at 17:30
  • To add to the confusion there is no central patch panel and while i have found other lose CAT5 wires in the utility room there are yet other CAT5 wires that seemed to be hooked to a telephone junction box - I am trying to figure out which wires are which. Can I put a meter across any of the twisted pairs to confirm a phone signal ? If so which ones? – MLind Feb 5 '15 at 2:33
  • You can do that - you'll see around 48VDC of voltage across the pairs (if all phones are "on-hook"). If all you see are unterminated pairs, then the only answer to "which pair" is "whichever pair is connected to the phone network". If the cable is terminated, the inner 2 pairs should correspond to the phone line (the next outer pairs would be the second line). In standard telco color coding, that's the red/green pair for line one, yellow/black for line 2. I'm not sure what, if any, color coding standard exists for CAT-5 used for analog phone service. – Johnny Feb 5 '15 at 3:00
  • I found which wire was which from 9 unmarked Cat 5 cables by selecting a pair in each cable (orange white/orange for example; touch a 9V battery to the 2 wires at one end and touch a LED spot to the 2 ends of the pair at the other end of the cable. You need 2 people to make it quicker but it worked. – user55208 Jun 14 '16 at 15:33
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Since they went to the trouble to wire a pair of CAT-5 cables at each receptacle, they likely wired them all back to a central patch panel in a closet or wall cabinet that looks something like this:

enter image description here

If that's the case, then none of the outlets are "live" and would need to be patched over to the appropriate service (data or phone). Unless they are patched to something, then they are not live. How to actually patch to phone or data varies depending on how the phone and internet service are wired to the wiring closet.

If they really just left the other ends dangling and unterminated, the best thing to do would be to terminate the to a patch panel like the one pictured (which is surprisingly easy with the right punch down tool)

If the jacks/wires are not labeled, you can trace (and test) them with a cable tester like this:

http://www.kleintools.com/catalog/cable-testers-accessories/vdv-scout-pro-tester-kit enter image description here

this is just one example of a cable tester - there are lots of cable testers out there of varying quality, but this is moderately priced and works well for home use. There are cheaper testers that just use an array of LED's to show you the cable status, and there are (much) more expensive testers that will do a full cable qualification to certify that it will run at the rated speed. I've used this model and it works well for home use, one nice feature it has for cable tracing multiple cables is that it has several numbered terminators that you can plug into one end, then when you plug the meter into the other end, it will tell you which one it sees

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If they are not terminated, they have no signals at all, until you terminate them and connect them to something.

Blue/white(with blue stripe) is normally the "line 1" pair in cat 5 cable used for phones. Green/white(with green stripe) is the standard line 2 pair, in the presently unusual case that you actually have 2 land-lines. Pins 4&5 for blue, 3&6 for green, on an 8-pin RJ-45. I would open the box (or the "Customer side" of the box if it's a Telco disconnect, not as likely inside the house - normally inside the house wiring is all yours) and look.

If you have a meter, it's easy (if tedious) to sort out the unconnected ones, if you are saying that you have a utility room that has a bunch that not terminated there either - strip a little and connect a 9V battery to a wire pair, then go looking for the other end with 9V across the wires you put it on. Label as you go, and it will get faster as you'll have fewer to check. Test leads with clips make this process easier but are not absolutely required.

Use reasonable care when testing for live phone lines - if it happens to ring, the voltage is significantly higher than the 48V you see when the phones are on the hook. On the other hand if it's completely dead (not as common with E911 laws) there may be no voltage at all.

  • I think he means terminates at the jacks. IMO the best bet is to do a visual. Find out where they go then you'll see what's feeding them. Then you can get a cheap tester to identify each one. – Speedy Petey Feb 4 '15 at 21:10
  • That's correct - bear wire at the wall plate. To add to the confusion there is no central patch panel and while i have found other lose CAT5 wires in the utility room there are yet other CAT5 wires that seemed to be hooked to a telephone junction box - I am trying to figure out which wires are which. Can I put a meter across any of the twisted pairs to confirm a phone signal ? If so which ones? – MLind Feb 5 '15 at 2:13

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