…exact, in fact I need to detect power failure (troubleshooting) in a 50V direct current circuit, normally traversed by a current of about 0.2A. The circuit is about 100 m, the pair of wires is sectional 1,5 mm2, placed inside a corrugated. The absence of contact is useful because I have no possibility to dissect the installation. If that's not possible, I can dissect i 50 Vcc and inject a frequency signal to search for it with a paired receiver, do you think it is possible?