Find Wiring with Oscilloscope

Handymen or women know the problem: You would like to drill a nice hole in your living room wall in order to hang some pictures or install a TV or lamp wall mount. No biggie! You just get your beloved HILTI ready and get really excited about using this awesome tool, showing the concrete wall who’s boss! But wait! You remember distantly that your landlord said there might be some electrical wiring hidden somewhere, where you wanted to drill, because the electrician didn’t follow standard procedure. Bummer!

Oscilloscope Wiring Waveform

Picture Credit: “COS6100A OSCILLOSCOPE 100MHZ” by mikael altemark is licensed under CC BY 2.0

Usually wiring is horizontal or vertical

Best practice for electrical wiring is to always go horizontally or vertically. So if there’s a power plug right above where you wanted to drill, chances are high you might hit wiring. But sometimes, especially in older houses, these rules weren’t really considered and wiring just goes criss-cross. So how to find that hidden wiring? My colleague, who is of course an engineer like 80% of the German population (the other 20% are Beamte), had an amazing idea when she was trying to find some wiring in her rented flat.

There’s an easy way and there’s a German way

Where many of you consume-oriented inhabitants of the capitalist world might just go to the next hardware shop an buy a cable finder, doing so would be way too easy for a German engineer. We do it complicated but correct! Therefore we borrow an Oscilloscope from work (as said before, we are all working at engineering companies, where this is standard equipment), plug some unshielded cable into it and bring that close to the wall. Thus the cable works like an antenna, catching the 50 / 60 Hz frequency of alternating current. Eureka! There’s our wiring! Now you can safely go ahead and drill without the risk of getting electrocuted! After that you really earned yourself a Feierabendbier!

Disclaimer: Needless to say, I don’t assume any responsibility for you drilling into your walls! You do this at your own risk! 🙂


Do: Use Oscilloscope to find wiring
Read: The user manual
Listen: To the hum of 50 Hz

Featured Image Credit: “Tektronix Type 453 Oscilloscope” by stanhua is licensed under CC BY 2.0

Written by Tom

Day-time engineer (of course!), free-time vinyl-nudger and uber-organised model citizen. When living together with Julia, we never thought we could be good examples.

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