The Amalgamated Transport and General Workers Union (ATGWU) have withdrawn strike action due to take place on Monday and will instead hold a further meeting with ESB.
In a statement released this evening the ATGWU said: "The issue of contractor use and their effect on the sustainable jobs, earnings and conditions of all of our members will be a fundamental issue for us at such negotiations.
A prolonged strike at ESB could lead to blackouts, as repairs would most likely not be done to breakdowns in the distribution network
"They are not issues that can be addressed through an agreement that has served ESB well but that now needs to be built upon at the next stage.
"We have been offered a meeting where we have been told we can address scheduling for negotiations on Monday 19 September 2005
"ATGWU withdrew from industrial action due to begin on 12 September 2005 to allow further space for a resolution of this dispute.
"To allow the best possible environment for this meeting to take place we are now withdrawing notice of 1 day's strike action...We will make further decisions when that meeting has taken place."
The dispute is over the extent to which outside contractors are involved in the delivery of a €3.6 billion programme to upgrade and modernise the company's network.
The ESB had earlier said that while there was "no immediate threat" to power supplies, prolonged strike action could inconvenience the public and "damage the economy".
Some 1,700 external contractors are employed by ESB Networks alongside some 2,200 staff technicians, more than half of whom are represented by the ATGWU.
The ATGWU says a number of ESB apprentices are unable to secure jobs with the company because of the extent to which outside contractors are being used. Its members balloted last month in favour of industrial action.
Power supplies will not be immediately threatened if the action by more than 1,000 ATGWU members goes ahead, but a prolonged strike could lead to blackouts, as repairs would most likely not be done to breakdowns in the distribution network.
Earlier today, both the Technical Engineering and Electrical Union (TEEU) and Siptu today said they had no dispute with the ESB.
In a statement issued this afternoon the secretary of SIPTU's Energy Branch, Jimmy Jordan, said: "SIPTU at this point in time has no dispute with the ESB on apprenticeship issues but we are concerned that the proposed action could endanger the future of the remaining apprentices.
"We have been advised by the ATGWU that they will enter into a dispute with the ESB on Monday September 19th, 2005, but we have had no request from that union for support. We also understand that no request for an all out picket has been made by the ATGWU to the ICTU."
"We are therefore instructing our members to report for work on Monday and to carry out their normal duties."
TEEU General Secretary, Owen Wills, also added that the union's executive is instructing its members to report for work and carry out their normal duties on Monday, regardless of whether or not the ATGWU places pickets at company premises.