My son asked his contractor to arrange for 14-50 outlet. Instead of a surface mount, he installed a standard, plastic 4" box, and none too well -- it wiggles a bit. We installed the outlet, but the 4" galvanized 14-50 box does not fill the 4-1/2" hole the contractor cut in the sheetrock. Is there a standard 4" cover with a 2-1/8 in hole for the 14-50 receptacle? Have you dealt with this issue?