Panasonic KX-NCP500 Installation Manual page 57

Outside Installation
Trunk
PT-interface CS
If you install an extension outside of the building, the following precautions are recommended:
a.
Install the extension wire underground.
b.
Use a conduit to protect the wire.
Note
The surge protector for an extension and CS is different from that for trunks.
Installation of an Earth Rod
Surge Protector
Trunk
Earthing
Wire
(Underground)
(Main Building)
Surge Protector
Trunk
Terminal
Board
Extn.
Extn.
Extn.
SLT
PT
CS
PBX
Earth Rod
Extn.
PBX
Surge
Protector
Earth
Extn.: Extension Line
3.2.9 Surge Protector Installation
(Another Building)
SLT
PT
PT-interface CS
CS
Installation Manual 57