One of the most damaging industrial disputes in the country may have come to an end after Ausgrid power workers suspended four months of work bans after striking a surprise pay deal.

The Electrical Trades Union reached the in-principle deal with the Sydney and Hunter Valley energy supplier after a night of intensive bargaining on Tuesday, with pay rises of 7 per cent, 3 per cent and 3 per cent over three years, guaranteed role progression and allowance increases.