Hi.
An electrical joint causes problem during data transmission
I have two questions:
1. Why it produces noise in a telephone line while it is twisted enough to make sufficient contact with other wire.

2. Does it causes problem with even power transmission(i.e. transmitting power for home appliances.240V 50-60Hz.)

 

Initially, when the wires are clean, there will be good contact between the two wires - no problem.
After some time, the wires will oxidise and there will be a high resistance contact between them. As the wires move, the resistance may change causing a variable volt drop across the joint, and so the telephone signal will be noisy.

At higher power, there is sufficient voltage to "burn through" the high resistance joint.
The joint will get hot, there could be a large volt drop across the joint, but unless the resistance becomes very high, you may not notice the problem.

JimB

__________________
Experience is directly proportional to the value of the equipment ruined.

 

Capacitive coupling, is the answer, the two wires with an insulator between them form a capacitor which can pass AC signals and result in crosstalk.

__________________
I also post at the following sites:
http://www.stop-microsoft.org http://www.heated-debates.com
Screen name: Aloone_Jonez

 

Wires you want to keep connected for any length of time should be soldered or at least taped to keep them from oxidizing.