Condom conductivity test. Condoms being tested for holes. The condoms are filled with water, attached to electrodes (white) and placed in salty water. Rubber is an insulator and therefore the electric current from the electrode should not be conducted out of the condom. However, if the condom has a hole in it the current will be conducted to the salty water, triggering an alarm. All condoms must undergo the conductivity test before sale. Photographed at the National Testing Laboratory, France.