Underground joint locator
Underground joint locator
(OP)
Morning gents (and ladies)
I have a job the now at a hydro power station where the client is experiencing a loss in production and believes this is due to moisture ingress into underound electrical joints along the 3km route of the 10core 5 pair BS5308 Type 2 Part 2 hill instrumentation cable. These are supposed to be epoxy scotch cast joints according to the as-builts, which have northing and eastings also kindly provided, however the client doesn't want to entertatin verifying the accuracy of the drawings by inputting the co-ordinates into a suitable GPS device and digging trial holes which I have previously suggested.
The electrical contractor has since went bust, and we have learned the complete route wasn't reticulated in ducting, obviously a £ saving measure on the contractors part.
I have tried the use of the Bicotest T625 time domain reflectometer on site to identify any changes of impedance at these joint locations but also had no joy. Loop continuity and megger testing was also carried out between cores and individual cores to earth and although IR ohmic values has degraded over time, all seems that it should still function as intended as a signal path.
Does any body else have any similar experiences to trying to locate such buried items or ideas how I can keep a diffulcult client happy? [ponder]
Many thanks in advance.
I have a job the now at a hydro power station where the client is experiencing a loss in production and believes this is due to moisture ingress into underound electrical joints along the 3km route of the 10core 5 pair BS5308 Type 2 Part 2 hill instrumentation cable. These are supposed to be epoxy scotch cast joints according to the as-builts, which have northing and eastings also kindly provided, however the client doesn't want to entertatin verifying the accuracy of the drawings by inputting the co-ordinates into a suitable GPS device and digging trial holes which I have previously suggested.
The electrical contractor has since went bust, and we have learned the complete route wasn't reticulated in ducting, obviously a £ saving measure on the contractors part.
I have tried the use of the Bicotest T625 time domain reflectometer on site to identify any changes of impedance at these joint locations but also had no joy. Loop continuity and megger testing was also carried out between cores and individual cores to earth and although IR ohmic values has degraded over time, all seems that it should still function as intended as a signal path.
Does any body else have any similar experiences to trying to locate such buried items or ideas how I can keep a diffulcult client happy? [ponder]
Many thanks in advance.





RE: Underground joint locator
Lost energy isn't "lost". it goes somewhere and any amount of energy dissipated at a connection will usually progress to a complete failure fairly soon.
Bill
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"Why not the best?"
Jimmy Carter
RE: Underground joint locator
Joints could then be examined externally for any possible ingress of moisture due to damage or poor jointing procedures.
All suspect joints could be cut out & replaced.
RE: Underground joint locator
Way I look at it, the lient needs to trace and mark the complete cable route anyway for future fault finding purposes, it should have been done in the initial works. If it had been, along with joint markers, this job would have been a hell of a lot easier.
RE: Underground joint locator
I was called in to troubleshoot a 4kM long cable that was newly installed to remote control a Large Pump Station.
After locating under ground joints using as built drawings(???) & TDR I found a 300m middle section had been carefully joined to itself!!
The Company Consultant's excuse was that since the Installation Contractor's qualifications were scrutinised before contract was awarded, they did not consider that the installation should be checked or supervised!
Consultant & Contractor were stuck off bidding list.
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