Panasonic KX-TDA15 Installation Manual page 57

Outside Installation
Surge Protector
Trunk
Terminal
Board
Extn.
SLT
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)
Trunk
Hybrid
IP-PBX
Extn.
Extn.
PT CS
Hybrid
IP-PBX
Earth Rod
2.2 Installation of the Hybrid IP-PBX
(Another Building)
SLT
PT
Extn.
CS
Surge
Protector
Earth
Extn.: Extension Line
Installation Manual 57