As ESB Networks technicians belonging to the Independent Workers Union hold their fourth day of strike action, the company has said that the level of impact on customers remains "low".

The IWU, which is not recognised by ESB Networks, claims to represent over 500 of the company's network technicians.

However that figure is disputed by recognised unions representing the remainder of the grade (Connect, SIPTU and Unite).

The striking union insists that it is receiving a high level of support from members of other unions refusing to pass their pickets - though the ESB has refused to confirm how many staff have been absent during the four days of strike action.

The current stoppage is due to end at 8am tomorrow - but the IWU Strike Committee will meet later this evening to decide its next move.

The union insists the dispute centres on the right to be consulted over the outsourcing of certain work to the private sector - though other observers claim this is in reality a union recognition row.

It has said it is prepared to attend the WRC and provide emergency cover but ESB Networks has refused to engage with the union.

The company has alleged that the IWU strike is unlawful but has so far stopped short of seeking an Injunction to halt the industrial action.

However, it has launched proceedings against the union for a number of issues including defamation and conspiracy.

In a statement today, the IWU said that by its actions ESB Networks was placing all of the employment law legislation and accepted codes of practice in the State in jeopardy.