Nearly 500 workers at EDF energy struck on Tuesday of this week, against a national 2 percent pay offer and two regional pay disparities.
They are members of the Unite union, and include workers who fix and install electricity meters.
Unite said the strike caused delays for EDF customers.
The strike hit EDF centres in Bexley Heath, Bristol, Camden, Crawley, Exeter and Plymouth.
Workers were set to strike again on Thursday of this week, with a demonstration at the firm’s headquarters.