Cadent engineers have started banning overtime from 10th May.
The move comes one month after thousands of workers at Cadent Gas voted for strike action over a pay dispute.
The overtime ban includes stopping working additional hours and members will withdraw from pre-planned overtime to cover gaps.
The GMB Union said the industrial action could potentially cause outages at homes and businesses throughout five regions in England; North West, East and West Midlands, East Anglia and North London.
Gary Carter, GMB National Officer, said: “Despite members voting overwhelmingly for strike action, as a gesture of goodwill members will begin with a short-term overtime ban.
“But workers will not hesitate to escalate to strike action if the company doesn’t come back to the table with an improved pay offer.”
Martin Rimmer, Chief of People at Cadent stated: “We are disappointed that an agreement was not reached with the GMB regarding the balanced whole package pay deal we have offered our operational field force.
“We would like to assure our customers that we will continue to provide them with a safe and reliable gas network throughout any action.
“Whilst the GMB has concentrated on asking for a higher pay increase, more than the 6.08% pay increase over two years that we have offered, they have not taken into consideration the whole pay package.
“Especially the pay increase to our lowest paid colleagues to a minimum of £10 per hour, ensuring that they are paid above the Real Living wage. We also gave £750 lump sum payment to our field force and have made significant changes to the terms & conditions of some contracts based on colleagues’ feedback.
“The pay review and negotiations had been productive over the past 18 months, with the majority (c. two thirds) of our workforce agreeing the pay increase, and this has been paid to them.
“Despite the rejection of the pay deal, we have implemented the pay increase to our lowest paid to a minimum of £10 per hour, ensuring that they are paid above the Real Living wage. We believe this is the right thing to do.
“Whilst all of our colleagues will receive a 6.08% pay increase, the impact of the £10 an hour minimum wage means that 37.5% of colleagues on our new contract will receive more than a 13.9% pay increase over the two years from June 2021, if the pay deal is accepted.
“This is in addition to the £750 lump sum payment made in January 2022 to our field force and staff colleagues.
“It is disappointing that an agreement could not be reached on the fair pay deal and the broader package offered to colleagues.”