Electronics > Repair
Finding fault location for broken power cables in walls
antenna:
too bad it would be a fire hazard, could short other end and inject HV from a fencer or modulated tesla coil and listen for the audio where it jumps lol
watchmaker:
--- Quote from: calzap on December 05, 2024, 07:00:01 am ---Problem with inspection holes is there are vertical studs at about 0.5 m intervals. So, a bunch of inspection holes would be needed for a 4-m stretch. In this particular case, I think things are even more complex. City water comes into the house in the same wall as the dead outlets. That’s why the sprinkler flow switch is in it.
Based on certain structural features, it appears a lot of the PEX and fittings were fastened in or on that wall when the house was replumbed. Then some new studs with lots of notches for PEX were fastened broadside to the wall, and those were covered with drywall extending floor to ceiling. It’s possible that all or most of the original drywall was removed.
And of course, that’s the 4-m section where the fault probably is. No surprise. That’s where the plumbers and carpenters did their sawing, drilling and fastening. So, best guess is there is a layer of drywall, 50 mm gap filled with PEX and fittings. Then maybe another layer of drywall. Then more PEX and electrical cables. There is no knowing at this point whether the new studs line up with the old. That’s why I’d really like to locate the fault as precisely as possible before drilling or cutting holes.
If I can’t do that, simplest fix will be to go in the attic and find the cable from the GFCI outlet. Install a junction box and drop a cable through the wall to the dead outlets. Haven’t been in the attic yet, so it may be more complex than described above.
Mike
--- End quote ---
You have my sympathy. We went thru this with a wall sconce controlled by three switches. After checking all 3 switches I called sparky. He did determine the break was between the primary switch and the sconce (forgot how). Still had to open the dry wall to install a new section.
May be easiest to just bite the bullet. I would cut out the 12' section of drywall at the cable height (12' by 2') and then it is easy to replace the drywall. You would also have the old holes for passing the cable.
Kind of like first aid, first you gotta visualize the issue even when you know it will hurt.
themadhippy:
--- Quote ---could short other end and inject HV from a fencer or modulated tesla coil and listen for the audio where it jumps
--- End quote ---
was thinking similar.personally id run a new cable in,or maybe
timeandfrequency:
Hello calzap,
I could successfully locate a broken cable behind a 5 x 2,5 m drywall with this stuff. Could narrow down the exact location to 10 cm.
You need two transmitters, set with two diffferent codes. Additionnal transmitter here.
Connect the transmitters at both ends of the broken cable.
Follow the cable with the receiver, by beginning close to one transmitter. When the code displayed on the receiver changes, you're spot on.
Read carefully the manual. Best result are obtained when the mains is switched off, but it is not compulsory. The transmitters can be connected to live circuits.
Try with and without ground/earth connexions (the transmitters have two banana plugs, one of those is ground/earth).
Good luck.
Same gear from Fluke. Probably compatible with the one above (same features/ frequency). A bit more expensive^^.
MarkL:
I use one of these telco line toners from Tempo Communications (formerly Progressive Electronics), model 200EP and 77HP:
https://www.amazon.com/Tempo-Communications-701K-G-Generator-Probe/dp/B083Z7V7C2
The transmitter can be connected to a ground and the dead wire, and then traced by walking around with the receiver next to the wall. The reception range is around a foot, but can be varied with the volume/sensitivity control.
This is meant to be used on ***UNENERGIZED*** wires. If you leave the AC on, that will be the end of the transmitter.
Cost is about USD$80. There are plenty of knockoffs for $35 or less if you search for "200EP", but I don't know how well they work. I would stick with the original.
EDIT: It probably goes without saying, but where the tone stops or gets significantly weaker is where the break is in the wire.
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