NoteThe surge protector for an extension is different from that for trunks.Installation of an Earth RodTrunkPBXEarth Rod(Underground)Surge ProtectorEarthingWire1. Connect the earth rod to the surge protector using an earthing wire with a cross-sectional area of atleast 1.3 mm2.2. Bury the earth rod near the protector. The earthing wire should be as short as possible.3. The earthing wire should run straight to the earth rod. Do not run the wire around other objects.4. Bury the earth rod at least 50 cm (20 in) underground.Note• The above figures are recommendations only.• The length of earth rod and the required depth depend on the composition of the soil.3.2.10 Backup Battery ConnectionThe backup battery and Back-up Battery Cable provide a backup power supply to allow full use of the PBXin the event of a power failure. In case of power failure, the backup battery automatically maintains the pow-er to the PBX without interruption.User-supplied Items• Backup Battery: VRLA (Valve Regulated Lead Acid) 12 V DC × 1• Back-up Battery Cable: KX-A227WARNING• There is a danger of explosion if a backup battery is incorrectly replaced. Replace only with thesame or equivalent type recommended by the battery manufacturer. Dispose of used batteries ac-cording to the manufacturer’s instructions.• Make sure that you do not short the backup battery or cables.CAUTION• Make sure that the Back-up Battery Cable is securely fastened to both the backup battery and thePBX.• Make sure that the polarities of the backup battery and wiring are correct.• Use the correct type of Back-up Battery Cable for the PSU.3.2.10 Backup Battery Connection58