* Union negotiations to resume Tuesday * Five-day heatwave to end Sunday By Scott DiSavino NEW YORK, July 8 (Reuters) - New York power company Consolidated Edison Inc said the voltage reductions, also known as brownouts, ended on Sunday morning as the brutal heatwave eased its grip on the Big Apple. Con Edison, which has been talking to its locked-out 8,000 member unionized workforce about a new contract, reduced the voltage in some neighborhoods in Brooklyn and the Bronx last week as replacement crews mostly made up of managers worked in the heat to fix some broken equipment serving those communities. Con Edison told customers in the affected neighborhoods they could keep running their air conditioners despite the voltage reduction. Most customers do not even notice a voltage reduction, which mostly affects incandescent lights, hot water heaters and some motors. The company however did ask all of the 3.2 million homes and businesses it serves in New York City and Westchester County to use energy wisely during the heatwave. High temperatures in New York reached 92 degrees Fahrenheit (33 degrees Celsius) on Wednesday, 95 F on Thursday, 93 F on Friday, 97 F on Saturday and 90 F on Sunday, according to AccuWeather.com. As the heatwave baked the Big Apple, Con Edison and the union participated in negotiating sessions to end the lockout, which started on July 1 after the company told the union employees not to report to work after the settlement ended without a deal last weekend. The union and company had their last negotiating session on Saturday and were expected to meet again on Tuesday at noon Eastern Time (1600 GMT). The heatwave will ease its grip on the city later Sunday. Temperatures next week will return to near normal levels with highs expected in the mid 80s Monday through Friday, AccuWeather.com said.