* Unions to urge members to join all-out picket
* Talks to be held on Wednesday to resolve dispute
DUBLIN, July 7 (Reuters) - The union representing striking Irish electricians said on Tuesday that other affiliates of the Irish Congress of Trade Unions had agreed to hold ballots and ask their members to support them with an all-out picket.
Employers hope talks with unions on Wednesday will help end the strike they fear could cripple industries already weakened by one of the deepest recessions across the developed world.
But the union representing the 10,500 contractors taking part in the indefinite strike over wages -- the first major industrial action since Ireland went into recession last year -- remained defiant.
"Our pickets have already made an enormous impact on the electrical contracting and construction sectors and this will be multiplied many times over once the all-out pickets are put in place," the Technical Engineering and Electrical Union (TEEU) said.
The dispute centres around wage increases of about 11 percent the electricians say they are owed for a number of years.
Employers have said they cannot afford to give them more money and instead are looking for a wage cut of 10 percent.
At a time when Ireland is struggling to repair damage to its investor image from twin banking and fiscal crises, the strike has hit hundreds of construction sites and hurt production at Irish units of companies such as Intel, Pfizer, Microsoft and Cadbury.
Output has been curtailed in many places as workers not directly involved in the pay dispute did not cross the electricians' picket lines.
A court is expected to decide on Wednesday whether to extend a temporary injunction against TEEU to stop picketing Dublin's St. James's Gate brewery where Diageo makes Ireland's trademark Guinness stout for the Irish and British markets.
SIPTU, one of Ireland's largest unions with 200,000 members, said it would complete its ballot by the end of next week.
"As by far the largest union in construction our involvement in the dispute will see a serious escalation," it said. (Reporting by Andras Gergely; Editing by Matthew Jones)