** Shares of US construction and engineering firm Emcor Group EME.N fall 1.54% to $634.74

** Co announces sale of its UK building services unit to OCS Group UK Ltd for ~190 mln pounds ($255.36 mln) enterprise value

** The company states the deal will improve its operating margin profile

** Emcor plans to use the proceeds to expand electrical and mechanical construction and mechanical services businesses

** Despite the session's drop, shares are up 40% year-to-date

($1 = 0.7440 pounds)

(Reporting by Krisha Bhatt)

((Krisha.Bhatt@thomsonreuters.com))