Today, we just replaced the phone line which was damaged due to moisture and were causing a great deal of disturbance and noise in the phone. What exactly causes this noise? Does the signals gets broken by the water entering the phone line?

  • \$\begingroup\$ Would you immerse a battery in water? Does your cell phone work properly after an immersion in water. \$\endgroup\$
    – Andy aka
    Dec 22, 2014 at 18:38
  • \$\begingroup\$ No, but a phone line seems like just a piece of copper wire. \$\endgroup\$
    – cpx
    Dec 22, 2014 at 18:39
  • \$\begingroup\$ Maybe the sheild get damaged and more ambient noise goes on the line \$\endgroup\$
    – GmodCake
    Dec 22, 2014 at 18:53
  • \$\begingroup\$ @gmodcake common cat 3 and 5 used in residential wiring is unshielded Anyways \$\endgroup\$
    – Passerby
    Dec 22, 2014 at 18:58

2 Answers 2


Too long for comment: To expand on @passerby a bit - the noise you hear is the result of the water forming a partial short-circuit between the two wires that come to your house from the telephone exchange; because of various chemical effects due to electrolysis, gassing, etc this is a lot more noisy than bridging the line with the equivalent resistor. Often the characteristics of this partial short are such that it will 'ring on' - ie application of the higher-voltage AC ringing will cause the resistance to drop; this appears to the exchange equipment as if you have answered the phone, and it will stop the ringing current and open the transmission circuit; this kind of fault is called 'Ring Trip' in (British) telephone engineering jargon.


Copper can tarnish and corrode/pit from moisture contact on loose or broken insulation or connection points. It can also make shorts occur between multiple conductors.


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