Break in line, in wall,

[bqtchef]

How do I locate a break in 22/2 wire within the wall? I've used a tone so I know the route within the wall it's unfortunate their two lines because the tone bleeds into the other line. I really don't want to cut a bunch of holes in the wall searching for the break and want to keep everything hardwired. Suggestions?
Thank you

 

[c hris527]

How far is the run? Are you able to disconnect them from the sources and tie it off on one end and test for open with a OHM meter? or continuity tester. If it shows open then you might find a halfway point and open it up there and then you can test that way and work in the direction of the break, perhaps you can even tie on and do a pull from that half way point. You claim you know where they are in the wall with a toner so it should not be too bad to figure. If you cannot do a new pull starting from either end then you will no doubt being probing your wall at some point.

 

[bqtchef]

It's a short run from the Motion to door contact (approx 20 ft) The continuity test failed on red, black is ok. I was hoping in the 21st century we have a tool for checking such thing but guess not.
I will definitely try tieing /pulling the line through but I believe there are too many 45 degrees bends in the way.

 

[Netwalker]

Tone generator will find approximate location of the break if you can get the probe a handful of inches away. I believe they may even make some for cat 5. Check Amazon.

 

[Rakin]

TDR (time domaine reflectometer). There are several types of TDR s out there from basic digital display to full on graph display. You just need something basic. Try to find someone who has one. Mine is an $8000 piece of equipment but I use it daily. Tone and probe won’t work for an unbalanced open because the bleed over will have you all over the place.

Try checking the most obvious points first. Like any splice or connection, or anywhere that may have been compromised. Keep in mind you may not visually see the break even when you are looking right at it. Wire can break under the insulation from stress like hard bends and being under tension.

 

[bqtchef]

I've looked at a few TDR (thank you btw) what do you think of the VDV Scout Pro 2?
I'll see if I can borrow one but if not how accurate are they at pinpointing the break in line?

 

[Rakin]

I've looked at a few TDR (thank you btw) what do you think of the VDV Scout Pro 2?
I'll see if I can borrow one but if not how accurate are they at pinpointing the break in line?

I have no experience with that particular instrument. The lowest cost device I’ve used is a fluke ts100 and it was good for short lengths of a few hundred feet or less and was best the shorter the length of cable being tested. Which was the main reason I used it, for instance when I had gotten so close to my short or open and cut up a road or parking lot and made an opening and couldn’t see the fault with my $8000 TDR because I was say only feet away from it the ts100 was a life saver. Or if I was chasing shorts and opens in 20’ of inside house wire it was great.

Might look on eBay for something used. That stuff is on there all the time, probably telco techs selling their company issue stuff. And then you can always turn around and get your money back from it on eBay. Or if you know anyone that works in telco they might have one or have access to one if they are in outside maintenance. May be a few networking guys that have one but I doubt it.

If you don’t mind give me as much details of the cable you have issues with and I can probably run through some of the most common problems I see.


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[cage771]

Yup.....you need a TDR for this. My CAT5/6 MAP tester has a simple but effective TDR built in (just an inexpensive MAP tester from Amazon).

From experience with what you are facing, create a pair of RJ45 pigtails (one for the transmitter and one for the receiver). Connect the 22/2 to a pair on the pig tail. Run the length test twice (one in either direction). This should get you very close to where the open is.

Good luck!

 

[Holbs]

question: what caused a break in the cable? Only time I've seen a break was because of a new random screw or other remodeling in the area was done.
And was this resolved?

 

[Rakin]

question: what caused a break in the cable? Only time I've seen a break was because of a new random screw or other remodeling in the area was done.
And was this resolved?

I’m curious also.

In my experience repairing inside wire Ive seen rodents chew lines, Bad splices. Constant moisture coupled with dc voltage causing it to go open. Things settling on top of it in the attic or the house settling and getting pinched between truss and joist. Lightning burning it, usually at a weak spot or a place with low insulation or splice. And of course improper install, being pulled or kinked causing weak spot. A lot of the time it’s a combination of these things that eventually does it in.






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[bqtchef]

"time domaine reflectometer" My IT Director had one so we did an experiment. We created the same issue without the wires being in the wall and it didn't work. I think the lines were too short.
The house was built in 2005 same time the alarm was installed and the line never worked. The installer used a wireless contact to solve the issue.
I wasn't about to poke holes in the drywall just be 100% all hardwire so I did the same.

 

[tangent]

"time domaine reflectometer" My IT Director had one so we did an experiment. We created the same issue without the wires being in the wall and it didn't work. I think the lines were too short.
The house was built in 2005 same time the alarm was installed and the line never worked. The installer used a wireless contact to solve the issue.
I wasn't about to poke holes in the drywall just be 100% all hardwire so I did the same.

I think whether you can make a toner or tdr work in this application would depend on the frequency and amplitude of the signal used. In the case of TDR, the characteristic impedance of the cable may also be relevant. Signals behave a bit differently in coax / cat cable compared to 22/2.

 

[Rakin]

I think whether you can make a toner or tdr work in this application would depend on the frequency and amplitude of the signal used. In the case of TDR, the characteristic impedance of the cable may also be relevant. Signals behave a bit differently in coax / cat cable compared to 22/2.

Every tdr i have owned or used had Vp control settings for the gauge and characteristics of cable being tested. A toner will just bleed over usually.


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