One hundred and twenty control room staff at the Electricity Operations Control Centre, Wokingham; and the Network Operations Centre, Warwick, will start their action.

The decision to go for a ban was taken by ballot in January by a 93% majority, after protracted negotiations with National Grid. The company has committed to harmonising the arrangements for shift staff working overtime as currently different payments are made to gas and electricity shift staff.

Detailed discussions commenced over a year ago but without an implementation date being agreed. Prospect members are demanding that improvements to overtime are backdated given the length of time it is taking to reach a final agreement.

Prospect National Secretary Emily Boase said: “It takes a lot to push control room staff, who are professional engineers dedicated to safe and continuous operation of the nation’s power supply, to take industrial action. But National Grid has done it by its refusal to set a date for change.”

Prospect’s National Grid branch remains open to talks with the company at any time. It is seeking a range of improvements to overtime arrangements with effect from July 2008.

Shifts and overtime are worked regularly by all professional staff in ENCC and NOC as both control rooms are 24-hour operations. A joint working group was set up with the company in 2005 to harmonise terms and conditions for staff covered by the National Grid and gas staff handbooks, but a final package has yet to be agreed.