Need Help with Landscape Lighting

[HermanTX]

I am trying to find a break in a wire for landscape lighting that was previously installed some years ago. There are 3 wires connected at the transformer in which 2 wires are functioning to their respective lights. The 3rd line is getting 12V at the transformer but the lights are not working on the walkway where the lights are located. Since all 6 lights are out, I assume I have a break in my wire between the transformer and the lights.
I have no idea where the wire was run other than it goes around the pool.

I have read about an underground cable locator that can be used for low voltage lighting. Does anyone have any recommendations for one of these devices? Also, if there are any additional ideas of what I need to check, all ideas welcomed. I am trying to avoid digging up about 70 feet of wire trying to find a break. II have not been able to run a continuity test but I think this undergound cable locator can do that as well.

All help is appreciated.

 

[Mdragger88]

To be honest I would just bury a new wire & abandon the other one.

 

[ajw22]

This one looks like it may be worth a try. I have not used it but have looked around at these wire tracers since I need to find the location of a 12V transformer for some lights in my house with the wire running through the wall.

https://www.amazon.com/dp/B08CKFKX7N

Although it may be less expensive for you to just run a new wire to your lights.

 

[generessler]

Unfortunately no first hand experience. Searching "wire break locator" in Amazon provides a range. I think for $50 I personally would give this one a try based on reviews. If they're fakes, at least they're well done. A chance to avoid tearing up grass and landscaping is worth way more than $50 to me. Ymmv

 

[ajw22]

Unfortunately no first hand experience. Searching "wire break locator" in Amazon provides a range. I think for $50 I personally would give this one a try based on reviews. If they're fakes, at least they're well done. A chance to avoid tearing up grass and landscaping is worth way more than $50 to me. Ymmv

The reviews for that product are sketchy. Many of the 5 star reviews are from a reviewer who go0t a free product to review. They always find positive things to write to stay in the free review program.

The product only has 17 ratings and 4 reviews of which 3 reviews where from the free program. Hardly a good sample.

 

[JoyfulNoise]

Use Fakespot on Amazon to see if stuff is legit. An F score is never good …

 

[Newdude]

So locating the wire is one thing. You'll need an open meter to know it's broken at 37 ft. (Etc). Then on older wiring it may just be finding the first fault, which isn't *the* fault.

I'm with @Mdragger88 that you'll have twice the headache trying to fix it and you'll likely end up replacing it anyway. (For 3X the headache).

 

[dfwnoob]

When I used to do telecom and security installs, we had a TDR tool that could detect breaks in a wire with a "distance to fault" readout, but that was a multi-thousand dollar Fluke tool. I assume something probably exists that's cheaper now. But as @Newdude says, that's just to the first fault OR it could be detecting where a lamp is hooked up. And it won't help you locate it.

I would run new wire.

 

[generessler]

The reviews for that product are sketchy. Many of the 5 star reviews are from a reviewer who go0t a free product to review. They always find positive things to write to stay in the free review program.

The product only has 17 ratings and 4 reviews of which 3 reviews where from the free program. Hardly a good sample.

As I said, ymmv. Lots of products on Amazon have AI-generated reviews mass uploaded. These appear to be real.

 

[Newdude]

@HermanTX if you really want to go for it, (or any future readers do), this Klein meter will tone (wand sold separately) and locate faults.

Meter
Wand

these type toners are really made for toning through sheetrock. Plaster walls, brick or dirt will likely kill the tone.

What about a metal detector ? When you find a line of hits, you got it.

 

[HermanTX]

Thanks for all the quick feedback. I researched about 10 models on Amazon prior to my original post which were different from the ones discussed above. I will continue to review and most likely will purchase one to try. I like new gadgets!!!
However, I know my fallback is to run a new wire, which is quite doable. I just need to ensure I have a cool morning to do all the digging as it is about 70ft.

 

[Mdragger88]

You can run the wire & connect it without burying it first to to test it & be certain it solves the problem before going through all the other effort.
Be sure to disconnect it/ turn it off when burying it of course

 

[phonedave]

If you have a multi-meter that measure capacitance, you can shoot the distance to the open.

The capacitance between the two wires in the circuit is directly proportional to the length of the wires. You can take a known good section of the cable and measure the capacitance and length to find the capacitance per foot, and then measure the bad section to find the distance to the fault. You can get snazzy (and expensive) meters that will do this automatically (like a Sidekick) or use the aforementioned TDR, but they are a lot more expensive. You can also try welding the fault using Megger if you have access to one, that makes it much easier to locate.
However if you don't know where the cable actually runs, then that is not much help.

 

[dfwnoob]

That's a trick I never knew! Thanks, @phonedave !!

 

[Newdude]

That's a trick I never knew! Thanks

I bet there is a handy dandy web calculator these days that takes the gauge, resistance, wire type and wire temp and converts it to footage to the fault like the TDRs.

 

[phonedave]

I bet there is a handy dandy web calculator these days that takes the gauge, resistance, wire type and wire temp and converts it to footage to the fault like the TDRs.

Not quite. Resistance per foot of a given wire gauge at a given temperature is readily available. And that works great if you are trying to shoot to a dead short. You measure the resistance of the loop, take half of that (because it is a loop) and then you calculate your distance. In old school copper telephony, if you do not have a dead short, instead you have a high resistance fault, perhaps caused by some pinholes in the insulation that now got wet, you can make it a dead short. You used to do so by using a breakdown set - applying high voltage to ionize the moisture and weld the pairs together. Breakdown sets have not been used for quite some time - because much of the copper is plastic instead of pulp insulation now, and if you do not use the set correctly, things go on fire, or worse, people get hurt or killed. Now they make a set called the ToneRanger (others exist) that uses a combination of relatively low AC voltage (200V or so) and then a superimposed DC voltage to break down oxidation on a fault.

Anyway, all of that was how to shoot to a short. The OP is looking to find a open. To do that, you need to measure the capacitance between the two wires in the cable (or the broken wire and the sheath if it is a sheathed cable). That is a lot less standard because it depends on the distance between the two conductors in the cable, as well as the actual characteristics of the copper itself.

The TDR does it because it knows the rate of propagation of a signal in the copper cable (based on gauge and temp). When the signal hits a fault, part of it is reflected back. The TDR (Time Domain Reflectometer) measures the round trip time of this reflected signal, and calculates the distance. Same way an OTDR works in fiber, but its got that O - for Optical. Sends out a light signal instead of a electronic signal.

I haven't had to mess around with this stuff in years - I do project management and process improvement now - had to dust off some cobwebs in my brain here.

 

[HermanTX]

Not quite. Resistance per foot of a given wire gauge at a given temperature is readily available. And that works great if you are trying to shoot to a dead short. You measure the resistance of the loop, take half of that (because it is a loop) and then you calculate your distance. In old school copper telephony, if you do not have a dead short, instead you have a high resistance fault, perhaps caused by some pinholes in the insulation that now got wet, you can make it a dead short. You used to do so by using a breakdown set - applying high voltage to ionize the moisture and weld the pairs together. Breakdown sets have not been used for quite some time - because much of the copper is plastic instead of pulp insulation now, and if you do not use the set correctly, things go on fire, or worse, people get hurt or killed. Now they make a set called the ToneRanger (others exist) that uses a combination of relatively low AC voltage (200V or so) and then a superimposed DC voltage to break down oxidation on a fault.

Anyway, all of that was how to shoot to a short. The OP is looking to find a open. To do that, you need to measure the capacitance between the two wires in the cable (or the broken wire and the sheath if it is a sheathed cable). That is a lot less standard because it depends on the distance between the two conductors in the cable, as well as the actual characteristics of the copper itself.

The TDR does it because it knows the rate of propagation of a signal in the copper cable (based on gauge and temp). When the signal hits a fault, part of it is reflected back. The TDR (Time Domain Reflectometer) measures the round trip time of this reflected signal, and calculates the distance. Same way an OTDR works in fiber, but its got that O - for Optical. Sends out a light signal instead of a electronic signal.

I haven't had to mess around with this stuff in years - I do project management and process improvement now - had to dust off some cobwebs in my brain here.

This is all very useful. Thanks for sharing.

 

[Toxophilite]

Do you know if they were wired hub and spoke or daisy chain? If latter, you might go to closest light not burning on string and find the tee connection bad.

 

[HermanTX]

Do you know if they were wired hub and spoke or daisy chain? If latter, you might go to closest light not burning on string and find the tee connection bad.

I can only surmise based on the 1 cable that is working and is visible. The lights are mounted on a pergola and there is a cable running the length on top of the beam and each of the lights is tee'd off of it. So, I do not know if one of those tee junctions is faulty would it affect the lights further down or just the 1 light it runs to.

I do plan to dig up around that first non-working light to look at that connection.

 

[Toxophilite]

I can only surmise based on the 1 cable that is working and is visible. The lights are mounted on a pergola and there is a cable running the length on top of the beam and each of the lights is tee'd off of it. So, I do not know if one of those tee junctions is faulty would it affect the lights further down or just the 1 light it runs to.

I do plan to dig up around that first non-working light to look at that connection.

You have 3 runs on your transformer to 3 individual strings if I read right. 2 strings work fine. 3rd string doesn't. I'm assuming the lights for the 3rd string are all teed into that one cable wire. At each light, the power cable is cut and spliced with the fixture wire for each fixture and to continue on to the next. If a connection is bad at a splice, the power can't continue on. Only would need to verify voltage at first in string, or, first not functioning. Pic of wire splice: