Grounding system in marinas: The micro-system approach

The Micro-System design approach of electric systems has the purpose to improve their safety, maintenance, operation and reliability. The Micro-System design approach can be applied to the case of marinas, where pleasure craft may be moored. Marinas require a structured architecture for the shore electrical power distribution system, which supply power to distributed loads. In addition, the design must provide for solutions to electrical hazards, as possible stray currents circulating through the earth and the water. The Island-grounding system, which utilizes separation transformers grounded at the mid-point of their secondary sides, allows to supply loads divided into “islands” as independent electrical areas. This distribution system is an effective way to protect persons from shock hazards in installations with contained demand load, and to greatly limit electrical interferences among systems. According to these authors, the TN-Island-grounding system is the best option to supply shore power to pleasure craft in marinas. This paper substantiates that the TN-Island-grounding system allows the development of “hybrid” solutions that lend themselves to the application of either the NEC-USA or the IEC-UE codes and standards. This important achievement would contribute to eliminate technical obstacles and discourage market barriers still existing worldwide.