Gary Sullivan, president of the Utility Workers Union of America Local 369 in Braintree, said the workers, represented by six UWUA locals, would get an average pay raise of 12 percent over the life of the new four-year contract. He said the British utility company, which runs its U.S. operations out of its Westboro headquarters, would also increase staffing levels in its New England operations by between 20 and 30 percent during the four year period.

‘‘Everybody feels very good,’’ Sullivan said on Friday night. ‘‘Things moved rather quickly today. I think the company realized that we were serious about our needs.’’