TM 5-6115-593-12 TO 35C2-3-463-1 c.  Indoor Installation.  Keep the area well ventilated at all times, so that the engine generator set will receive a maximum supply of air.  If a free supply of fresh air is not available, provide duct work, with an opening at least as large as the radiator, to the outside of the installation.  If louvers are used at the air entrance, increase the duct work size by 25 to 50 percent.  Loosen the screw and nut which secure the weather cap to the exhaust outlet and remove the weather cap.  Install a gas-tight metal pipe exhaust outlet to the outside of the installation.  The termination of the exhaust pipe shall be such that hot gases or sparks will be discharged harmlessly and will not be directed against combustible material or into an area containing flammable gases or vapors.  Use as few bends in the pipe and as short a pipe as possible.  The exhaust pipe should include a low point with suitable means for draining of condensate. Provide metal shields, 12 inches (305 mm) larger in diameter than the exhaust pipe where the line passes through flammable walls. Wrap the exhaust pipe with asbestos if there is any danger of anyone touching it. Refer to figure 4-6 for dimensions, air flow requirements. WARNING Do not operate the engine generator set in an enclosed area unless the exhaust gases are piped to the outside.  Inhalation of exhaust fumes will result in serious illness or death. d.  Leveling.  Set up the unit as level as possible (within 5 degrees), and keep it as level as possible during operation. e.  Grounding.  The engine generator set must be grounded prior to operation.  The ground can be, in order of preference: (1) an underground metallic water piping system, (2) a driven metal rod, or (3) a buried metal plate (figure 4-7).  If the effectively grounded portion of the buried metallic water pipe is less than 10 feet (3 m) due to insulated sections or joints, this preferred grounding method must be supplemented by an additional driven metal rod ground or a buried metal plate ground.  A driven metal ground rod must have a minimum diameter of 5/8 inch (16 mm), if solid, or 3/4 inch (19 mm) if pipe, and driven to a minimum depth of 8 feet (2.4 m).  A buried metal ground plate must have a minimum area of 9 square feet (0.8 m ), minimum thickness of 1/4 inch (6.4 mm), and be buried at a minimum depth of 4 feet (1.2 m).  The ground lead must be at least No.  6 AWG copper wire.  The procedures for making a ground connection are shown in figure 4-7. f.  Slide Hammer Procedure. WARNING Nuts must be tight on the slide hammer rod. Loose hardware may result in serious injury. CAUTION The slide hammer (figure 4-7, sheet 2) striker plate and top nut must be tightened to the end of the threads on the slide hammer rod.  The slide hammer rod and ground rod section must make firm contact inside the ground rod coupler.  Damage to rods, plate and couplers could result if left loose. NOTE If the slide hammer is assembled, go to step (b). (a) Connect the slide hammer striker plate (1) to bottom of the slide hammer rod (2). Tighten to the end of threads. Connect lockwasher (3) and nut (4) to bottom of the slide hammer rod (2).  Tighten firmly against the striker plate (1). Connect the ground rod coupler (5) to the bottom of the slide hammer rod (2).  Connect the ground rod section (6) to the other end of the ground rod coupler (5).  Tighten the ground rod section (6) to make firm contact with the slide hammer rod (2). (b) Remove nut (4) from the top of 4-12