4.6　The Earthing of Telecommunication Equipment

4.6.1　During the overall planning of telecommunication rooms，the main distribution frame should be installed in the vicinity of cable vaults at the first floor.The earthing connection shall be led in from two directions of the earth grid nearby.

4.6.2　Unshielded signal cables or power cables shall not be laid on the outer wall.In case inevitable，all such cables shall run through shielded metal pipes，and two ends of metal pipes shall be connected to the common bonding network.

4.6.3　The telecommunication equipment should be placed at an area 1m away from the pillar of outer wall.And the equipment cabinet shall not contact the outer wall directly.

4.6.4　For the telecommunication system of the comprehensive telecommunication building，when its subsystems or equipment are interfered due to the earthing mode，one or more local earthing bar（s）should be mounted in equipment rooms.The earthing conductors for different telecommunication subsystems or equipment shall connect with the corresponding local earthing bar firstly and then with the floor earthing bar.

4.6.5　When the transmission equipment is interfered by different earthing modes，anti-interference measures such as the isolation treatment by disconnecting one end of the shielding layer of the shield transmission line shall be taken.

4.6.6　Earthing conductors of telecommunication equipment racks with the demand on individual protective earthing shall be led in from the main earthing conductor or the branched main earthing conductors in equipment rooms.

4.6.7　Digital distribution frame（DDF），ODFs or boards，data servers and racks shall be earthed.

4.6.8　The earthing of DC power distribution system for telecommunication equipment of the comprehensive telecommunication building shall be in accordance with the following requirements：

1　DC-C-CBN system may be designed according to Fig.4.6.8-1.

Fig.4.6.8-1　DC-C-CBN system

2　DC-C-IBN system may be designed according to Fig.4.6.8-2 and Fig.4.6.8-3.

Fig.4.6.8-2　SPC DC-C-IBN system on BR bus bar

Fig.4.6.8-3　DC-C-IBN system with individual SPCB

3　DC-I-CBN system may be designed according to Fig.4.6.8-4.

Fig.4.6.8-4　DC-I-CBN system

4　DC-I-IBN system may be designed according to Fig.4.6.8-5.

Fig.4.6.8-5　DC-I-IBN system

5　DC-C/DC-I mixed type system may be designed according to Fig.4.6.8-6.

Fig.4.6.8-6　DC-C/DC-I-CBN mixed type system