** Oppenheimer upgrades energy contractor Quanta Services PWR.N to "outperform" from "perform"; sets an $800 price target

** Says it is now taking over analysis of Quanta Services from Kansas City Capital

** Brokerage says utility and tech spending supports long-term growth, with additional upside from power, pipelines and transmission projects

** Adds Quanta's large workforce positions it to take on some of the biggest upcoming U.S. infrastructure projects

** Shares down 1.3% at $724 in early trading

** 23 of 31 brokerages rate the stock "buy" or higher, 8 "hold"; their median PT is $800 - data compiled by LSEG

** Including session's moves, shares up 72.4% YTD