Testing buried cables for faults

[Spoon242]

Guys,

I had a call today from a campany who has a large cable buried over 100M and believe it to be damaged somewhere along the run. I have not looked at it......
This is not something I have encountered before, but how do you go about testing such a cable and working out where to dig?

 

[Chrisnic]

this is a specialised field really mate used to do it when I worked for the dno usess specialist meter echo pulse shows a wave form with reflections where there are faults and joints or you can cut into sections start at the centre and eliminate good sections and re joint back then go again but walk the run first you may see where there has been recent excavations that might point to someone having damaged the cable

good luck if you take it on

Chrisnic

 

[Spoon242]

Thanks for your quick reply.

I have a feeling that its not worth me getting involved in for a couple of reasons.
1 - I dont have the meter and not trained in it
2 - It 52 miles from travel for me.

Anyone in Portsmouth who would be interested, PM me and I will pass details on to the company

 

[Engineer54]

this is a specialised field really mate used to do it when I worked for the dno usess specialist meter echo pulse shows a wave form with reflections where there are faults and joints or you can cut into sections start at the centre and eliminate good sections and re joint back then go again but walk the run first you may see where there has been recent excavations that might point to someone having damaged the cable

good luck if you take it on

Chrisnic

That's the problem with those electronic echo pulse detectors, they don't only show the fault location, but if there are any joints in a long or very long cable, they show them too.

It's never been an easy task to locate faults in buried cables, the old system was to use a ''Wheatstone Bridge'' megger, just as accurate (if you were experienced in using the kit) but would still see joints as well as the fault itself.

As Chrisnic suggested, this is best left to a specialist company, that will have all the test equipment to locate the faulty section of cable!!!

 

[mogga]

CAT and GENNY Genny produces a signal and the CAT ( preferably RD400) company name is Radio Detection hence RD will pick up genny signal This is easy stuff IF you have had the training and 3 days plodding around a field where there are numerous broken cables burried faulty cables for you to find There are instruments that can tell how far along the cable the fault is ect and use the RD400 to find the cable its one ot those"Black arts" some guys just couldnt do it some picked it up straight off I would liek to think I could still do it but havent had practice for a few years

 

[Short Circuit]

i had a similar job a couple of months ago, i hired a cable tracer from a tool hire shop and it couldnt find a cable if it were in the wholesalers - i tried a few holes where i thought it might've been with no results, other than a bad back then ended up getting a friend who works for the DNO to find the fault and he pin pointed it, within a foot or so! Cant remember the name of the tester he used but no doubt simlar to that Chris has mentioned. The fault was rock that had been dropped on top of the cable and pointed down which eventually broke through into the cores! Easy to fix once we found it!

 

[HandySparks]

Guys,
I had a call today from a campany who has a large cable buried over 100M and believe it to be damaged somewhere along the run.

Just out of interest, did they say why they thought the cable was damaged? What were the symptoms?

 

[Spoon242]

Just out of interest, did they say why they thought the cable was damaged? What were the symptoms?

There were talking of intermittant drop in a phase.
They also mentioned that years ago there was a join introduced and recently, August 2011, there was a drain installed which looks like the brickwork is sitting on the cable.

The join they said took 1.5 days to dig up with a jcb, Haha!

 

[Engineer54]

There were talking of intermittant drop in a phase.
They also mentioned that years ago there was a join introduced and recently, August 2011, there was a drain installed which looks like the brickwork is sitting on the cable.

The join they said took 1.5 days to dig up with a jcb, Haha!

Did they say how deep it was buried?? must have been a good few metres down to take a JCB 1.5 days to reach it!! lol!!

There you go, only 2 places to dig, and one being a good chance, of being where the fault is ...lol!!