* Con Ed, union agree to resume talks on Tuesday * Voltage reductions lifted in city neighborhoods * New York City bakes as heat wave persists July 7 (Reuters) - Contract talks between Consolidated Edison Inc and locked-out union workers ended on Saturday after a few hours with both sides agreeing to meet again on Tuesday as New York City baked in extreme heat. Con Ed spokesman Alfonso Quiroz confirmed negotiations between the company and the union had concluded and will resume Tuesday at noon. Saturday's negotiations started at about 10 a.m. EDT and went until around 1 p.m. EDT, he said. In a statement, the union said talks with Con Edison will continue on Tuesday at a New York area hotel. John Melia, the spokesman for the Utility Workers Union of America Local 1-2, representing 8,000 Con Edison union workers locked out by the company on July 1, could not be reached after Saturday's session. However, hours before talks began, Melia told Reuters: "They locked us out, it's really up to them. We've given them an hour and if they come up with nothing, we have our federal mediators with us. We can imagine they're just as frustrated as we are." In addition to health care costs and wages, one of the major sticking points is the company's insistence that defined benefit pensions be changed to a 401(k) type of retirement savings account. Meanwhile, a heat wave broiled the Big Apple for a fourth straight day, further straining air conditioners, the city's power grid and replacement crews staffed mostly by Con Edison managers. Temperatures in New York were in the 90s (30s C) on Saturday and were expected to ease to about 90 F (32 C) on Sunday before returning to more normal levels around the mid-80s next week, according to AccuWeather.com. Friday night Con Edison lifted the 5 percent voltage reduction in some city neighborhoods that was imposed earlier in the week. Voltage reductions were made to protect the overall system and maintain service as crews repaired lines feeding power to communities. The reductions were the first since the company locked out the union workers after contract talks broke down. Con Edison said the voltage reductions were unrelated to the lockout, noting the company had reduced the voltage in parts of Brooklyn and Queens during a heat wave before the lockout in June.