source, or while the generator set is paralleled to another set which is op- erating. WARNING Do not attempt to connect the paral- leling cable while either or both of the sets to be paralleled is operating. Make sure that there is no input to the load from another source. Failure to observe this warning may result in death by electrocution. CAUTION Precise generator sets equipped with the electric governor system cannot be paralleled with sets that have the electro  hydraulic  governor  system. (1) If the generator sets are to share a load greater than the KW rat- ing of a single set, connect load ter- minal boards as shown in figure 2-3A. This  arrangement  allows  for  sharing  or transferring of the load between gen- erator  sets. (2) Open the left access door to the set compartment and remove the safety cover from the terminal board (figure  2-3). (3) Insert load leads through plate and sleeve assembly (figure 2-3) located to the left of the generator set air intake. NOTE The load terminal boards will accommo- date 2-wire single phase and 4-wire three phase loads. One or more single phase loads can be served alone or in combinations  with  three  phase  loads;  but the load on any one phase must not ex- ceed 100 percent of the current rating of that phase. Be sure that wire sizes are correct for load to be carried. (4) Connect the load to terminals marked L1, L2, L3 and L0 (figure 2-3). NOTE Make certain that the load terminal boards of the sets to be paralleled are connected  properly. Reading left to right, phase rotation for the phase loads is L1, L2, L3. Be sure L1 is connected to L1, L2 is connected to L2, etc. (5) Connect load leads and paral- leling cables as shown in figures 2-3A and  2-3B. NOTE After  load  connection,  tighten  binding nuts  with  plastic/phenolic  box  end wrench and install safety cover. NOTE Paralleling  of  tactical  precise  genera- tor  sets  requires  that  paralleling  ca- bles be installed and the shorting plug located on one of the paralleling re- ceptacles of each generator set be re- moved. 2-15.   Exercise   of   Engine   on   Standby   Service. A   diesel   engine   on   standby   service   that   is   custom- arily   operated   under   optimum   conditions   should   be exercised   at   least   every   30   days.   However,   under environmental   conditions   involving   extreme   tempera- tures,   humidity,   dust,   sand,   etc.,   it   maybe   found necessary   to   shorten   the   interval   between   exercise periods   teas   often   as   weekly.   Exercise   period should  be  long  enough  to  enable  the  engine  to  attain normal   operating   temperature   (160°-200°F)   while carrying,  if  possible,  at  least  50  percent  of  its normal  load. To   exercise   engine,   proceed   as follows: a.   Perform   the   preparation   for   starting   instruc- tion   shown   in   figure   2-6.   Make   complete   visual inspection  of  unit  to  be  sure  it  is  in  operating  condi- tion. b.   Start   engine   as   shown   in   figure   2-7.   After   an acceptable  warm-up  period,  run  engine  at  rated  speed with   whatever   load   is   available,   up   to   full   load,   for Change   12 2-18.1/(2-18.2 blank)