by these specifications. When necessary, the Contractor shall relocate outlets so that, when fixtures or other fittings are installed, they will be symmetrically located according to room layout end will not interfere with other work or equipment. Only zinc-coated or cadmium plated sheet-steel boxes conforming to the requirements of Federal Specification W-0-82la, of a class to satisfy the condition for each outlet, shall be used in concealed work. Boxes snall be installed in a rigid and satisfactory manner, eith er by wood screws on wood, expansion shields on masonry, or machine screws on steel work. Fixture outlet boxes on ceil ings shall be not less than 4-inch octagonal. Fixture out- let boxes in concrete ceilings shall be of the 4-inch octag onal concrete type, set flush with the finished surface. Fixture outlet boxes on plastered ceilings shall be fitted with open covers set to come flush with the finished surfac Switch, telephone, and receptacle outlet boxes shall be not less than 4-inches square, fitted with appropriate plaster covers, where necessary, to set flush with the finished sur face. One-piece gang boxes not less than 2 inches deep shall be utilized where necessary. Outlets in exposed work shall be of cast steel or alloy fitted with appropriate cov ers. Cast-metal fittings shall conform to the requirements of Federal Specification W-0-806. a. Outlet Devices shall be type specified on the drawings and shall be standard vapor-proof, watertight or explosion-proof as noted. 16-24. PULL BOXES AND CABINETS: The following requirement shall apply for pull boxes and telephone and signal system cabinets: a. Pull Boxes: Pull boxes shall be constructed oi code-gage galvanized sheet metal, of not less than the minimum size recommended by the National Electrical Code. Box+ shall be furnished with screw-fastened covers. Where several feeders pass through a common pull box, they shall be tagged to indicate clearly their electrical characteristics circuit number, and panel designation. b. Telephone and Signal System Cabinets: Each cé inet box shall be constructed with interior dimensions not less than those indicated on the drawings. Each trim shal: be fitted with hinged door and flush catch. Doors shall provide maximum-size openings to the box interiors. Boxes shall be provided with a 5/6 inch weatherproof-grade-plywoo backboard having a two-coat insulating varnish finish. 16-9