The ESB has been warned it could lose more than 40,000 business customers if it fails to prevent a strike over employees' pensions in the run-up to Christmas.
Retail Excellence Ireland (REI), which represents 11,000 stores in the country, said it has had 50 calls over the last few days from members who are worried about the impact on their trade.
Another 200 emails from members have backed the threat to leave the ESB supply.
Chief executive of the organisation, David Fitzsimons, said if the industrial action leads to power cuts the energy company will lose thousands of business accounts.
"I would have thought late last week it would have been resolved but as time goes on it's getting more concerning," he said.
"It's no good for consumer sentiment. We have dealt with enough crap over the last six years, and a lot of it was from outside the country - for an Irish state-owned company to lead us back to recession, it's really pretty disgusting.
"It's quite ludicrous this could not be dealt with in a closed room with mediation. It's disillusioning."
Three unions have agreed to industrial action to take place from 8am on Monday December 16 if a row with ESB management over a pension fund cannot be resolved.
The Technical Engineering and Electrical Union (TEEU), Unite, Siptu, the Union of Construction Allied Trades and Technicians (Ucatt) and the Energy Services Union meet ESB bosses on Thursday over the threat.
Ahead of the talks, Mr Fitzsimons' retail group estimated that about 44,000 company accounts would leave the ESB in the New Year if the strike hit business in the busy run-up to Christmas.
He said fresh fruit suppliers are most concerned about the prospect of power cuts and called on Minister for Communications, Energy and Natural Resources Pat Rabbitte to bring in emergency legislation to stop ESB from striking.
ESB has about 88,000 accounts in the small and medium enterprise sector.
The pensions row centres on claims by the unions over the level of a deficit and also over the company switching retirement plans from defined benefit to contribution, meaning workers are not guaranteed a certain level of payment.