More than 10,000 electricians are due to go on strike tomorrow in a dispute over pay.
The strike will see pickets placed on hundreds of construction sites, including high-profile projects such as Dublin's new airport terminal and the Lansdowne Road football stadium.
The action follows the collapse of talks at the Labour Relations Commission.
Earlier, the SIPTU General President gave his support to the electricians.
In a statement, Jack O'Connor said SIPTU would make a strong recommendation to its members to support the electricians in a ballot as soon as the TEEU seeks support through the ICTU.
He said the electricians must be supported by workers because the employers' objective of cutting pay and tearing up agreements reflects the aim of the wealthy to preserve their own assets and priviliged position.
