Extensive power outages have affected thousands of customers across the region after Tuesday's storms.

David Crough, from Essential Energy, says Inverell suffered the longest outage.

He's told ABC New England North West's program a cross-arm failed on Inverell's main power pole.

"At around 7:00pm on Tuesday night the network switched off 1,900 customers after sensing a problem and then, when our crews went to investigate, we switched off manually a further 5,600 customers," he said.

"In total, there were about 7,500 without supply and that was all of Inverell and the surrounding rural areas."

David Crough says the network identified damage to infrastructure.

"Basically, wet weather caused a cross-arm to fail [and], while that wouldn't normally be a significant event, this particular power pole is one of our main power poles near our zone sub-station in Inverell," he said.

"It actually contains four sets of power lines, whereas a normal pole will have one set of lines, so it was actually quite complex and a difficult and big job."

Around mid-morning on Wednesday around 3,400 households and businesses in the Gunnedah area were also taken off line.

Essential Energy says the unplanned power interruption also included parts of the Gunnedah CBD.

Power was restored in the Gunnedah area at lunchtime on Wednesday.