Earth Potential Rise in Public Spaces
The traditional telecommunications networks were housed in buildings and in shelters and cabinets in well gated areas, often several hundred meters or more away from areas of very dense populations. The new word in telecommunications is densification. The densification of the network unfortunately also means that in the modern telecommunications network, telecommunications facilities will be closer to the public domain and often in densely populated area. Examples of such infrastructure could include small cells, macro cells, fiber cabinets and other facilities. Most of these facilities when located in metropolitan areas would be powered via the AC mains from the local power supply network and would require a local telecommunications earth electrode and perhaps an additional AC protective earth electrode as well.
The author has noted two new trends and concerns that have emerged with the faster proliferation of telecom facilities in the public domain.
- EPR Due to Lightning on Telecom Tower: In countries where there is extreme population density close to macro cell sites, with a telecommunication mast present, significant earth potential rise, EPR problems can occur near the facility due to lightning strikes to the facility. This EPR problem has known to have resulted in damage to equipment in nearby residences and commercial facilities. Lightning surge that couple onto to power lines due to these near and other far lightning strikes have also known to cause damage to nearby neighbors, as often there is no or insignificant surge protection at these neighboring facilities. This problem causes significant headache and cost to telecom facility owners often resulting in large monetary compensations to neighbors, dissatisfaction about the carrier near presence and concerns about personnel injury or even potential death due to these events.
- EPR Due to Faults at Electrical Substations: Where the telecom service earth electrode or the AC protective earth electrode of the telecommunication facilities is inadvertently located in high EPR zone close to an electrical substation or HV transformer, large and sometime prolonged electrical currents from power system faults can migrate across to the telecommunications service earth electrode and get to the ground via unwanted paths. This can be a potential public hazard, a fire risk or a risk to electrical damage to equipment.
This paper will look at methods of grounding and surge protection at location where the above two EPR problems exist. The outcome of this paper will enable audience to implement practices in grounding, bonding and surge protection at sites in public domain where the above EPR risks are anticipated. The outcomes could potentially influence methods of grounding contained in future telecommunications standards related to grounding and protection of telecommunications facilities in densely populated areas are at facilities near electrical substations.