GROUNDING TESTING AND ADJUSTING SUBJECT: Grounding SRCR and SR 4 Generators BUSINESS: Building Services, Marine, Material Handling PRODUCT/APPLICATION: Generator Sets 1.    In  any  generator  set  installation,  the  frame  of  the generator  must  be  positively  connected  to  an  earth ground or to the hull of a vessel.  This connection is the first one made at installation, and the last one to be  removed.    If  the  generator  set  is  on  flexible  or resilient    pads,    the    ground    connection    must    be flexible to avoid possible breakage in later operation. Ground  connection  cable  or  straps  should  have  at least the current carrying capacity of the largest line lead   to   the   connected   load.      Joints   in   cables   or straps  must  be  clean,  free  of  electrical  resistance, and    protected    from    possible    oxidation.        Bolted ground  connection  joints  eventually  oxidize,  and  are frequent   sources   of   radio   frequency   interference. Silver   soldered,   bolted   joints   are   electrically   and mechanically sound. a. The  radio  frequency  noise  suppressor  in  early SRCR generators (below S/N 2000) is connected  to  the  generator  frame.    Inadequate frame   grounding   can   result   in   interference   to communication or audio equipment and improper operation of electronic governors. b. Where  local  codes  permit,  an  effective  ground connection  can  be  made  to  an  underground  all metallic  water  piping  system.    The  growing  use of  plastic  and  cement  type  water  pipes  makes water   pipe   connections   hazardous   as   well   as ineffective.      One   or   more   approved   corrosion resistant   ground   rods,   driven   at   least   ten   feet (three  meters)  into  damp  soil,  are  effective.    In dry,   sandy   soil   an   extensive   wire   ground   mat may be required. 2.      "Y"-connected   generators   should   have   the   neutral (and    frame)    grounded    when    the    generator    is installed    unless    definite    measures    are    taken    to prevent     grounds     on     the     load     side.          (NOTE: Noncurrent  2400-Volt  generators  are  manufactured with   the   neutral   wire   connected   to   the   generator frame.) a. If the neutral wire is not grounded and one of the load     phase     leads     becomes     grounded,     the resulting  voltage  surge  may  damage  the  noise suppressor   on   SRCR   Generators   with   serial numbers below 2000. b. If  the  neutral  wire  is  grounded  and  one  of  the phase  leads  becomes  grounded,  the  excessive current   will   open   the   load   circuit   breaker   or collapse    the    generator    voltage.        The    result depends   on   the   particular   generator   electrical characteristics,  type  of  fault,  and  circuit  breaker trip   rating.      An   under   voltage   device   may   be required     to     provide     adequate     short     circuit protection. c. There    are    some    instances    in    which    it    is undesirable to ground the neutral wire.  In these applications   where   definite   measures   (ground fault   protective   circuits)   have   been   taken   to prevent     grounds     to     the     phase     leads,     an ungrounded generator neutral lead is acceptable.      Ground   fault   protection   requires that  the  entire  group  of  distribution  circuits  be studied  and  treated  as  a  system.    The  owner should  engage  a  competent  consultant  if  a  new distribution  system  is  being  developed,  or  if  an existing system is to be modified for ground fault protection. 120