The 28-day break was prompted by major maintenance at the plant until June 13, Egat official Woraphoj Inthong said.
He added that the break would mean a daily absence of 700 megawatts while the overall output in the Southern region was 2,300 megawatts, or 100MW short of the actual demand each day.
Egat said the demand of electricity would reach 3,000MW by 2017, when more power plants would be needed.