Thanks a lot. I just killed my phones or phone line.
I use overvoltage protection extension cords with protection also for phone line.
I forgot that earth is connected to phone line trough varistors.
Strangely ADSL still works.
Edit:
Now when the telephone line is disconnected there is no leak current between two PCs.
Just a thought. These extension cords are pre ADSL so the varistors maybe have too low value.
What voltages are used in adsl?
This is what 8mA and some time do to a varistor:
**broken link removed**
Edit2:
Here is what happened: When I connected earths, leakage current got earthed trough phone line.
Mains unconnected earth is connected trough two varistors to both wires of the phone line.
Varistor to earthed phone line wire burned out, and then trough the other one leakage current killed my line.
I notified telephone company and I am hoping they don't find out what I did.