I came across this picture I took from the train going to Pisa from Florence.
Most of the trains in Europe are electric. They use suspended electrical cables to power the engines.
It makes sense to have warning signs cautioning people not to touch them.
You have to respect a country that uses a skull and cross-bones on their warning signs.
Translated at babelfish.altavista.com it says:
NOT TOUCHED THE THREADS
DANGER OF DEAD WOMEN