EDF Energy faces two days of strikes after 486 UK workers voted to take the industrial action in a row over pay.
The French based utility giant, which employs more than 16,000 workers in the UK, will face walk-outs in London, South Eastern, South West and Eastern regions on 6 and 8 May.
Trade Union Unite, which represents the workers, claimed the dispute means there will be delays in fixing and installing meters for customers.
"Unless the management of this highly profitable company sits down and engages in constructive talks, more industrial action is on the cards," warned Kasab Onay, a Unite regional officer.
The union said the dispute has three elements, including the company's 2013 pay offer of a 2% rise and a non-consolidated, one off payment of £200 for the year April 2013 to April 2014.
"The 2% pay offer fails to take account of the true cost of living," Onay argued.
"The argument is really quite simple. Those who make handsome profits for the company, our members, have a right to expect a pay rise that at least keeps up with the cost of living."
EDF sent IBTimes UK the following statement:
"We have offered employees working in our metering division a final pay offer of 2% with an additional lump sum of £200.
"The negations relate to the 2013 pay deal, which once agreed would be backdated to last April.
"We believe our final offer is fair and competitive. This is part of our commitment to our customers to ensure our costs are controlled and affordable.
"An identical offer was accepted last year by the vast majority of a much larger group of employees in the same part of our business - including those working in our customer service centres.
"We have been in continous talks with Unite and other unions for more than 12 months to agree the pay increase and we remain open as always to meeting employee representatives."