The Electricity Authority's report in to a toppled pylon has found the collapse was entirely avoidable.

The Transpower pylon north of Helensville fell - cutting power to 88,000 people in Northland - after unsupervised, inexperienced maintenance crews undid three legs at once.

The report found there was evidence removing all the nuts wasn't a one-off event.

ZB senior political correspondent Barry Soper says this incident came with significant economic impacts to Northland.

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