Last-ditch talks are to be held to avert a strike over pay by workers at energy giant EDF.
Around 500 members of Unite in London, the South East, South West and Eastern regions are set to walk out for 24 hours next Monday.
The union warned that the stoppage will delay the repair and installation of meters, as well as hit revenue protection.
The strike will be followed by a work to rule, unless the deadlock is broken during talks at the conciliation service Acas on Thursday.
Unite regional officer Onay Kasab said: "EDF Energy has a further opportunity to reach an agreement with Unite in last-ditch talks on Thursday and avoid major industrial disruption."