Arizona Public Service Company is the largest electric utility, and the highest tax payer in Arizona, USA, and the principal subsidiary of publicly traded S&P 500 member Pinnacle West Capital Corporation (NYSE: PNW), which in turn had been formerly named AZP Group, when Arizona Public Service reorganized as that holding company in 1985.   Arizona Public Service Company, a vertically-integrated electric utility, provides retail and wholesale electric services in Arizona. The company has ownership interests in or leases the coal, nuclear, gas, oil, and solar generating facilities. Its transmission facilities consist of approximately 5,883 pole miles of overhead lines and approximately 49 miles of underground lines, and distribution facilities comprise approximately 11,381 miles of overhead lines and approximately 17,572 miles of underground primary cable. The company owns or leases approximately 6,370 MW of regulated generation capacity, as well as purchases power. As of April 15, 2013, it served approximately 1.1 million customers in 11 counties in Arizona. The company was founded in 1920 and is headquartered in Phoenix, Arizona. Arizona Public Service Company is a subsidiary of Pinnacle West Capital Corporation.  