Nos. 99-1137, 99-1139 Argued January 19, 2000 Decided May 9, 2000 On Petitions for Review of an Order of the National Labor Relations Board. Marilyn S. Teitelbaum argued the cause for the petitioners in Nos. 99-1137 and 99-1139. Stacey A. Meyers was on brief for Local 702, International Brotherhood of Electrical Workers, AFL-CIO, the petitioner in No. 99-1137. Cary Hammond and Greg A. Campbell were on brief for petitioner International Union of Operating Engineers, Local 148, AFL-CIO in No. 99-1139