(AP) - Demand for air conditioning tightened supplies of electricity Monday as a heat wave that's blamed for at least 11 deaths in the past week covered much of the eastern half of the nation. Heat advisories were posted Monday from Kansas eastward through the Ohio Valley, and over parts of the Southeast. Seven deaths were linked the heat during the weekend in Ohio's Hamilton County, which includes Cincinnati, with five of the victims found Sunday in homes where the temperature was about 98, said Coroner Carl L. Parrott. The heat was expected to continue for a sixth straight day Monday in Illinois, where four deaths were blamed on the combination of high humidity and temperatures in the 90s. Louisville, Ky., peaked at 100 degrees Sunday, the city's hottest day in eight years. And Monday was expected to be the 11th-straight day with temperatures in the 90s. In New York state, more than 1,000 people were treated for heat exhaustion and dehydration at the three-day Woodstock '99 concert. New York state has had 11 days in the 90s so far this summer. That's typically the number of such days for the entire summer. The utility Cinergy, parent of PSI Energy which serves 655,000 customers in central and southern Indiana, said it would interrupt electrical service Monday to certain large-volume customers under special contracts to reduce electricity loads.