TM 5-3895-374-24-1 Access  to  the  main  lug,  main  breaker,  or  main switch  compartment  is  gained  through  a  hinged door    The    top    plates    (and    closing    plates    In bottom, if present) are removable for convenience     In     wiring     and     cutting     conduit openings. If  the  cable  is  brought  into  the  top  of  the  motor control center, the cable can be supported at the point of entry and the top plate by a 5" or smaller conduit,  SQUARE-Duct  wireway,  or  a  grommet centered over terminal L2. When  the  entrance  of  cables  is  at  the  bottom and the cables are  required  to  go  to  lugs  at  the bottom  of  the  section,  the  incoming  line  cables can be supported at the point of entry by a 5" or smaller conduit centered on the L2 terminal. Additional  wiring  space  can  be  gained  with  the addition of  a  pull  box  THE  INCOMING  POWER WIRING MUST BE SUPPORTED AND RESTRAINED  BY  THE  CUSTOMER  FOR  THE MAXIMUM AVAILABLE FAULT CURRENT For   available   fault   current   of   25,000   amperes RMS  symmetrical  or  larger,  further  support  can be added by restraining cables with a tight lacing of  3"  hemp  rope  or  a  material  of  equal  strength (such    as    cable    brace)    Begin    lacing    cables together  as  close  as  possible  to  lug  connection points   in   the   incoming   line   compartment   and continue  lacing  to  the  conduit  entry  point  The first and last ties should be anchored securely to the    motor    control    center    frame    to    prevent slipping  All  lacing  ties  should  be  spaced  for  the maximum available fault current In RMS symmetrical amperes nine inches is required for 25,000 amperes, six inches for 42,000 amperes, and   three   inches   for   65,000   amperes.   Where more     than     one     main     lug     compartment     is furnished for required ampacity, refer to Rule 12- 108  of  the  Canadian  Electrical  Code  to  assure equal division of total current among all incoming line cables involved. MAIN LUG COMPARTMENTS Wire Size American Wire Gauge Torque In or MCM Pound-Inches 310-200 200 250-400 250 500-750 300 MAIN & BRANCH FEEDERS Frame Ampere Torque in Size Rating Pound-Inches FA 15-30A 20 35-100A 50 KA 70-225A 250 LA 125-175A 200 200-400A 300 MA 4510DOOA 300 PA 800-2000A 300 Load and Control Wiring I-15B The  top  horizontal  wire  trough  and  the  vertical wire trough provide a convenient area to run load and   control   wires   Openings   between   sections permit the wire to pass through from one section into the next for interwiring. Because  of  the  intersection  of  the  vertical  and horizontal   wire   troughs,   wires   may   be   routed without  the  use  of  fishtapes.  On  7  space  factor construction, where the  bottom  unit  is  3  75"  (95 mm)  from  the  floor,  a  reduced  size  bottom  wire trough is available for bottom entry of user’s wire The  bottom  unit  and  unit  support  pan  must  be temporarily removed to gain access to this area. On  6  1/2  space  factor  construction,  where  the bottom  unit  is  9/2"  (241  mm)  from  the  floor,  a bottom cover plate is removed to gain access to an 8" (203 mm) high wire trough. Control  and  load  wires  are  routed  to  each  unit via wire ports These ports open into the vertical wire trough permitting  control  and  load  wiring  to enter  easily  After  wires  are  installed,  the  wires should be tied down with the wire ties provided in the vertical wire trough (Page 3-128)