Irrigation pivot fault finding

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Cow

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Eastern Oregon
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Electrician
I know there are a few on here that deal with farmers and pivots.

Have any of you had any luck finding faults where the wire is installed in conduit? Let's assume there hasn't been any recent digging, subsoiling, new fences, etc to give a guy a headstart on where to look.

We have a pretty expensive RD7000 locator that works great for locating and finding faults in regular direct buried wire. No problems there. But anyone that has done any locating and ran into the occasional fault in a conduit knows the fault finder/locator will lead you right to the couplings or poorly glued joints where water/moisture seeps out, and not to the actual fault location. This turns into a snipe hunt. Leads to lots of digging and speculating, not a lot of finding and repairing.

I have a Megger CFL510F TDR I bought new years ago, but haven't even made time to learn it and figure out if it'd be useful or not for situations such as this.:roll:

Thanks.
 
Cow said:
I know there are a few on here that deal with farmers and pivots.

Have any of you had any luck finding faults where the wire is installed in conduit? Let's assume there hasn't been any recent digging, subsoiling, new fences, etc to give a guy a headstart on where to look.

We have a pretty expensive RD7000 locator that works great for locating and finding faults in regular direct buried wire. No problems there. But anyone that has done any locating and ran into the occasional fault in a conduit knows the fault finder/locator will lead you right to the couplings or poorly glued joints where water/moisture seeps out, and not to the actual fault location. This turns into a snipe hunt. Leads to lots of digging and speculating, not a lot of finding and repairing.

I have a Megger CFL510F TDR I bought new years ago, but haven't even made time to learn it and figure out if it'd be useful or not for situations such as this.:roll:

Thanks.
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First good luck. We have managed to find a few via the cracks in the conduit. Note crack. They seem to be close to the fault or the few we found anyway.

We have a couple TDRs but my luck with those are very marginal, especially if the wires are not cabled together. The twisted triplex or quad will help considerably. Go to your supply house and find a cable of known length and the same size. Set it so you get the length you need to find the open end and then short them. You should see the deflection at the same distance. I found where the cable was bent at a sharp angle on the test spool I used. Right at the beginning. Unfortunately it also finds where you enter the ground. The water as it surrounds the cable in the conduit, etc. From what I read on mine the distance is plus or minus 10%.

We gave up and pulled the new in while pulling the old out. My faults were not even close, but I did not have cable conductors. They were loose.
 
Cow

i worked for Irrigators, Inc. in Moses Lake in the 1990’s. They are a Zimmatic Dealer. Don’t know how many circles they sell now, but back then, we installed around 50 every year. 100% of the underground we installed was inside conduit. We would get a service call for an underground fault every few weeks during the irrigation season. I don’t know what fault finding equipment they had back then, but the main service guy could find the fault fairly quickly and accurately. You might give them a cal, and ask their service Dept what their procedures are.
 
The aggravating part of the locate above was we installed it just over two years ago. One of the breaks I could not tell what caused it. The second looked like somebody hit it hard with a shovel. It was far enough into the run that it had to have come from where it was spooled for us. Custom cut. Only #2 Al.

Share what you figure out
 
The few times I have had to find open conductor in conduit I didn't have too much trouble. I have an older Rycom locator with a snooper probe and a return probe. The snooper probe if for general locating, the return probe is for locating faults by sensing where current is leaking and returning to the transmitter.

One locate I specifically remember was one where another electrician said it would be impossible to find that fault. I told owner I'd give it a shot. Connected snooper probe to first get a general locate of the conductor path. At a certain point the signal suddenly dropped in strength. Connected transmitter to other end and located from other direction - signal suddenly dropped at about same point. Told them to dig there and was within 5 feet of the open conductor. That is IMO reasonably accurate on an 1800 foot run.

Thing with fault finding is you have to do it to learn.

Had a direct buried line once make me dig a couple holes and find nothing. Both spots were questionable but was best indication I could come up with at the time. Then it occurred to me, I was digging in very dry soil (was a very dry year then) and that dry soil would affect return current for the fault finder. I seen a hose and sprinkler on the place (owner wasn't there at the time) and set it to water the conductor path and came back a few hours later. Found the fault real easily in this condition. Lesson learned.

Also learned (the hard way at times) when having hard time pinpointing things to make sure you have isolated what you are trying to find so you are not putting out signal on things you aren't trying to find. Occasionally this means turning things off for a general location when there is multiple items in the vicinity to carry your signal.
 
Our cable locator is supposed to find an Open as Kwire indicated. Signal drops, flag. Inject signal on other end, find where signal drops, flag. Open is between flags. IDR having much success with that method but a guy I used before I bought equipment did. I drove the path as he waved it out the window. Then we would get the fault finder out.
 
ptonsparky said:
Our cable locator is supposed to find an Open as Kwire indicated. Signal drops, flag. Inject signal on other end, find where signal drops, flag. Open is between flags. IDR having much success with that method but a guy I used before I bought equipment did. I drove the path as he waved it out the window. Then we would get the fault finder out.
Click to expand...
Occasionally I will get lucky and find fault with the cable locator function, signal suddenly drops. This usually works when it is a clean break for whatever reason. Farmer pulls ripper through conductors that are not all that deep, steel post driven into conductor, someone trenched something but claims they never hit anything....

The more difficult ones are when the fault is near the end of the run. If you don't locate from both ways those are usually difficult to determine.
 
This is not a pivot I'm dealing with directly, I just got a call from another EC asking me if I was good enough with my TDR to try and find it for them. Unfortunately, not!

The RD7000 we have now is a combination fault finder/locator. We used to have an older locator, with a separate fault finder we'd get out after we marked the path. I've been able to find opens just as Kwired mentioned by simply locating from each end until the signal goes away.

That was earlier this spring when a subsoiler tore several feet out of three different pivot feeders. That was pretty easy to find with a big gap between the wires working from both ends. The 16" wire depth in the middle of the circle probably didn't help....

We did dig down to it with a shovel quick though!

Thanks for the replies everyone.
 
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