The Energy Networks Association has described the storm damage in the North Wales as "nothing less than devastation for large parts of that area."
"The result is that we still have over 17,000 people centred in that area off power," said Tony Glover, from the trade body.
"The debris that flew around in North Wales were quite incredible and the impact it had on the electricity networks has resulted in a level of devastation that I don't think has ever been seen in the area, certainly not for decades," he added.
More than 2,500 schools in the North West of England could be affected today as teachers stage a walkout over pay, pensions, working conditions and jobs.
Members of the National Union of Teachers (NUT) and NASUWT will take part in a strike, the first in a planned national rolling programme of strikes across England and Wales which will continue in the Autumn term.
Twenty two authorities, and a possible 2,765 schools, across the North West will be affected as joint rallies are held in Liverpool, Manchester, Chester and Preston.
Chris Keates, General Secretary of the NASUWT, will address the rally in Liverpool at midday.
A walkout by Public and Commercial Services (PCS) union members is set to hit workplaces across the UK this afternoon.
Starting at 1pm, PCS members will take part in a half-day strike to tie in with a three month campaign over pay and pension disputes.
PCS general secretary Mark Serwotka said: "These walkouts, following our strike on budget day, are part of an ongoing campaign of industrial action and protests to put pressure on a government that is refusing to even talk to us.
"We have asked for talks but ministers and senior officials have refused, so we are taking action to oppose and shine a light on what are deeply unfair and unnecessary cuts to the living standards of hard-working public servants."