2N Door intercom 2N Helios - Manual, 1322 v3.0 - Manual (Page 31)

31
Grounding Terminal Connection - Mandatory
Any person that gets in contact with 2N® Helios may carry an electrostatic charge of
several thousands of Volts. Drawing one‟s finger near to the 2N® Helios metal panel
may result in spark discharge. The purpose of the grounding terminal is to protect the
product against this discharge. The terminal carries the charge from the panel to the
ground directly, not through the 2N® Helios circuits.
Where no grounding cable is available, it is possible to connect the grounding terminal
with any of the telephone line terminals*). In some telephone systems one line
terminal is directly connected with the ground, the others carry current to the ground
through overvoltage protection.
Note
 This connection eliminates direct connection of the line conductor onto the
panel because there is a protective element between the panel and the
grounding terminal.