A tool for installing various configurations of electrical boxes to framing studs during building construction includes a staff having graduations indicating distances from an end of the staff. A mounting fixture is slidably disposed on the staff and can be secured at a desired position along the length of the staff corresponding to a desired installation height for the electrical boxes. The mounting fixture may include pins for engaging apertures on an electrical box, and magnets for magnetically engaging metal electrical boxes, to help retain the electrical boxes on the mounting fixture during installation.