Wire mystery

[FiftytoOne]

I need to lay this out there for the experts or who ever would know. About 2 weeks ago one of my valves just quit working. After I determined that the current from my Hunter Pro-C was live and the ground intact I found that using the power from another valve proved the solenoid and valve were functional. So, I ran a new wire to the valve worked fine and irrigation bliss soon followed.

Today, two weeks later, the exact same thing happened to 2 additional valves. They are Hunter valves. And they are working fine. Fortunately, when running the last wire I ran 2 additional wires as well. I changed them out at the valve and controller and presto they're working like a champ.

My concern is that it will continue to happen. I have followed the original bundle of wire from the controller to the valves and can find no sign of chewing or damage.

The fact of the matter is that perfectly good solid copper wire is failing to conduct current to the valve. How could this happen? I am very perplexed at this strange occurrence. Does anyone have and explaination as to why just the wire would fail like this?

 

[hj]

wirw

Continuity check them but the most likely reason is a broken wire.

 

[Sponsor]

 

[FiftytoOne]

I checked continuity for all the wires. Nothing from A to B. The wires are bundled in a sheath of 8 wires. The run is straight and without unusual bends with no wear or tear. It has only been there for 6 months. I found it very unusual for one to go bad 2 weeks ago and and two today. The other 5 wires in the bundle are intact at this point. Any other ideas?

I know everyone is reading this post and thinking it's something simple. I had a buddy who installs irrigation with a lot of experience come over and double check my troubleshooting--he hasn't ever seen anything like this and is baffled as I am.

The only thing I can think is it might have something to do with the current going through the wire. However, it is low voltage and I don't see any melting indicating the wire is undersized.

 

[FiftytoOne]

Continuity check them but the most likely reason is a broken wire.

How do only 3 wires break in a bundle of 8 in a basically static state.

 

[Rancher]

Around here it's gopher damage, I've even lost a run of 12-3 buried 24" underground. I don't bury low voltage cable anymore without conduit.

Rancher

 

[CHH]

Damaged on installation?

Can't say I've had it happen with electrical but have had it happen with poly pipe.

Other possibility is poor quality wire or insulation. Hate to think that it might be the case but it's not impossible to have defects.

 

[FiftytoOne]

Damaged on installation?

Can't say I've had it happen with electrical but have had it happen with poly pipe.

Other possibility is poor quality wire or insulation. Hate to think that it might be the case but it's not impossible to have defects.

So far poor quality wire is the only possibility I can't disprove of the known possible causes. I just have a hard time convincing myself and for sure that would be a rare situation. The fact that I can visually inspect the entire run disproves anything is chewing on it. I would see it. This particular run is only about 30 feet under a crawl space. The wire rests on pipes under the floor so no fasteners were used. Didn't need them. So there shouldn't be a pinch.

I'm so curious, I really want to yank the whole run out and strip the sheath and inspect each wire just to satisfy myself. If I lose another one I will probably do it out of frustration.

 

[Jimbo]

You have pretty much proved that there are broken wires in the cable. The reason is not obvious, but the facts are indisputanle. How can these small solid strand wires be damaged with no visible jacket damage.....kinking, excessive bends, etc. You must carefully strip off the jacket to find the cause. You WILL find the broken wires.

 

[FiftytoOne]

You have pretty much proved that there are broken wires in the cable. The reason is not obvious, but the facts are indisputanle. How can these small solid strand wires be damaged with no visible jacket damage.....kinking, excessive bends, etc. You must carefully strip off the jacket to find the cause. You WILL find the broken wires.

The only thing I haven't done is test the integrity of each (3) of the wires. I'm going to do that today. I needed to get a pulse dohicky and see if it is in fact a break somewhere along the run. I hope your right. At least then I will know. It's the not knowing that kills ya.

 

[Jimbo]

. At least then I will know. It's the not knowing that kills ya.

Well, yes. But with all due respect, it is worrying about this for more than about 10 minutes before just replacing it and moving on.....that will kill ya, too!

 

[FiftytoOne]

Well, yes. But with all due respect, it is worrying about this for more than about 10 minutes before just replacing it and moving on.....that will kill ya, too!

No doubt. But I couldn't just let it go. I'm telling you anyone looking at this in person has just scratched their head.

Well I checked the resistance on all the wires and low and behold..........they failed. So yes, the wire is bad. But, where they are broken along this very straight unpinched run is mind boggleing. The only way I would be able to determine where the break is I would have to take out the entire bundle and strip the sheath the entire way and look for the defect. Well, how they broke is going to remain a mystery for now. If you looked at this line, which you can see in its entirety, you would just be amazed to find that 3 wires could have broken--not to mention after they worked fine for six months. Just amazing.

Fortunately, I ran several new wires to the valves after the first one went bad--I have all my valves in one place-and replaced the bad wiring and everything is running fine for now. What a pain it would have been had all the valves been located at various locations and each wire home run'd from those locations. What a PITA that would have been.

I appreciate your input and aid. If this site used rep points I would surely give you some for you assistance. This problem would usually fall into my no big deal I can see how that could happen category. Not this time. Out here. Phinn