Panasonic KX-TDA15 Installation Manual page 52

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