Wellington, March 16 NZPA - A faulty signal was the cause of an electricity outage in the Queenstown region this morning, Transpower says.

About 11,000 customers in the Wakatipu Basin were left without power for just over an hour when the fault occurred in a 110,000 volt overhead power line between Cromwell and Queenstown.

Power was lost to Queenstown, Frankton, Arrowtown, and Glenorchy about 8.40am and restored by 9.50am.

Transpower spokeswoman Rebecca Wilson said the Cromwell substation had sent a wrong signal to the Frankton substation.

"It sent a wrong signal essentially, so that's why the line tripped out of service," she said.

"We've taken that piece of equipment at Cromwell out of service and we'll be investigating that further."

Ms Wilson said the fault was unusual and had not occurred in at least the five years.

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