Northern Ireland Electricity (NIE) said the blackout was caused by an issue with the high voltage transmission network.

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It also wants any new high voltage transmission lines to avoid areas of outstanding natural beauty, national parks, world heritage sites and green belt land.

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It fell onto the main north-south high voltage power transmission line.

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Now there is growing concern that a really big storm might collapse much of the global electric grid, particularly in places with long high-voltage transmission lines such as Australia, Canada, China and the United States.

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The network of high-voltage "transmission" lines in the U.S. is rapidly aging and no longer can adequately support the country's growing demand for electricity.

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Transmission, especially long high-voltage lines that cross states, is extraordinarily hard to get approved, sited, permitted and paid for.

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That is the reason why the current emphasis in China is on the construction of 500kv extra-high-voltage lines and long-distance power transmission.

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Midwest ISO, which supervises 94, 000 miles of high-voltage lines, is considering ways to spread the costs of new transmission beyond local ratepayers and taking part in preparing a broad plan for the eastern interconnection.

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