EN 60728-11-2017 pdf download.Cable networks for television signals, sound signals and interactive services -Part 11: Safety.
Note that galvanic isolators, in case of improper design, can radiate or pick up inadmissible high-frequency energy. Therefore, compliance with the requirements of IEC 60728-2 should be checked carefully.
NOTE 7 Galvanic isolators can be damaged by overvoltages.
i) When changing or removing active or passive pieces of equipment (e.g. amplifiers, taps. etc.) or coaxial cable, care shall be taken to avoid hazardous voltages between the Interrupted parts (inner and/or outer conductors) by opening the loop caused by leakage currents from subscriber equipment. Provision shall be made to maintain continuity of the outer conductor system while units are changed or removed to avoid electric shock (shock currents). Examples are shown in Figure 6 and Figure 7. In addition, the inner conductors shall be safeguarded against contact
Note that before applying a temporary solution for equlpotential bonding the parts to be disconnected (e.g. the F connector of a disconnected cable) should maintain continuity to the temporary equipotential bonding link during the complete dc-installation/installation process.
NOTE 8 For requirements In Norway, see C.2.2.
j) Every connection of an protective bonding conductor or an earthing conductor to an earthing terminal shall be readily accessible and soundly made by the use of crimps, clamps, welded or hard-soldered joints.
k) All metallic enclosures, housings, mounting bays, racks and mains-supplied equipment, shall be provided with an external earthing terminal complying with IEC 60065 or
EC 60950-1.
Line-powered amplifiers, taps, splitters and transfer points should also be fitted with earthing terminals.
I) For antennas, which, according to Clause 11, do not have to be grounded, it is strongly recommended that at least the outer conductor of the coaxial cable connected to the antenna should be included in the equipotential bonding. Furthermore, all interconnected, conductive, accessible parts of the installation should be included in the equipotential bonding. For these connections, either of the following solutions is permitted.
• Connection to a bonding terminal or bonding bar by means of an protective bonding conductor (according to 6.2 c).
• Connection by means of the shielding of the coaxial cable. The DC resistance to the nearest point of equipotential bonding (or PE) shall be less than or equal to 5 ≤ in order that no hazardous touch voltage appears on exposed conductive parts (see also Annex A). The connection of the shield of the coaxial cable to the protective conductor shall only be disconnectable by means of a tool.
NOTE 9 For requirements in Norway, see C.2,2.
6.3 Equipotential bonding in meshed systems
6.3.1 References to other standards
Equipotential bonding shall comply with IEC 60364-4-44, IEC 60364-5-54. EN 50174-2, and
EN 50310.
6.3.2 General on AC mains
Due to the varying load, locally and versus time, of the individual phases of the AC mains supply in a building high balancing currents can occur in the neutral conductors. The neutral conductor currents are even increased by harmonic currents, which are emitted by certain electric loads like switching power supplies, energy-saving lights, etc.
NOTE For example, the third harmonic currents of the mains frequency in the three phases add knearly in the neutral conductor
6.3.3 AC power distribution and connection of the protective conductor
6.3.3.1 General
In low-voltage installations, different systems are distinguished by the type of earthing connection on the one hand and by the exposed conductive part otherwise (lEG 60364-1 or
EN 50310).
6.3.3.2 TN systems
There are three different TN subsystems with the following general characteristics.
a) TN-S system: Separate neutral and protective conductors throughout the system connected at the earthing point of the system.
NOTE No neutral conductor currents flow in the protective conductor.
b) TN-C system: Neutral and protective functions combined in a single conductor throughout the system.
c) TN-C-S system: Neutral and protective functions combined in a single conductor in part of the system.
6.3.3.3 TT system
The TT system has one point directly earthed, the exposed conductive parts of the installation being connected to earth electrodes electrically independent of the earth electrodes of the power system.EN 60728-11-2017 pdf download.