Model 6 Motor Control Centers – Instruction Bulletin PDF
80459-641-01, Rev. 10

Expansion

The MCC’s modular design permits easy expansion to keep pace with an expanding electrical system. When space is available in the existing MCC, starter units can easily be added. Units can be rearranged where necessary. Additional MCC sections can be added to an MCC when space is available. In some cases, units can be replaced with higher-rated units of the same physical size, for example, a 12 in. (305 mm) high, NEMA size one starter unit can be replaced with a 12 in. (305 mm) high, size two starter unit.

Ordering Information

NOTE: Arc-rated MCCs must only be expanded or added onto with arc-rated units/sections to maintain the arc containment ratings. Arc-rated units and sections have special labels identifying them as AR (arc-rated), typically in the locations shown in Typical Arc-rated Label Locations on Sections and Units. Customers must provide the previous arc-rated MCC factory order number when ordering additional arc-rated MCC equipment from the factory.
NOTE: Prepared spaces or unused spaces in arc-rated MCCs must be filled with arc-rated empty units. Arc-rated empty units can be ordered for use when rearranging units in an arc-rated MCC.

Typical Arc-rated Label Locations on Sections and Units

When ordering additional MCC equipment, include the following information:

  • Type of equipment supplied

  • Supply voltage, frequency, system type

  • Enclosure type

  • Enclosure finish

  • Control circuit voltage and frequency

  • Optional control circuit components required (control transformers, push buttons, pilot lights, selector switches. other items.)

  • Special features

  • The factory order number of the original MCC (the number is stamped into the structure nameplate on the vertical wireway door; the unit label inside each control unit also contains the factory order number)

When ordering new vertical sections, also provide the following information:

  • Horizontal and vertical bus capacity, material, and plating

  • Bus bracing (or available fault current)

  • Enclosure type and dimensions

Modifying MCC Units

DANGER
Hazard of Electric Shock, Explosion, or Arc Flash
  • Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E, NOM-029-STPS, CSA Z462, or local equivalent.
  • This equipment must only be installed and serviced by qualified electrical personnel.
  • Turn off all power supplying this equipment before working on or inside equipment.
  • Always use a properly rated voltage sensing device to confirm power is off.
  • Replace all devices, doors, and covers before turning on power to this equipment.
Failure to follow these instructions will result in death or serious injury.

Most MCC units are designed for easy removal from the MCC structure. Some units are not removable due primarily to the physical size of the unit.

De-energizing Equipment and Identifying Unit Type

Identify whether the unit intended for modification is a removable style or a fixed position unit. All removable units have stab connections to the vertical bus as shown on the electrical schematics and one-line diagrams provided with the MCC. Most removable units also have a twin handle cam mechanism (see Pulling the Twin Handle Cam Mechanism Forward). One notable exception is the Compac 6 control unit (see Operator Handle in the OFF Position), which is removable but does not have the twin handle cam mechanism.

NOTE: Modifications to arc-rated MCC units or structures can adversely affect the arc containment features and/or performance. Modifications to control circuit wiring are allowed. Modifications specifically covered in this instruction bulletin are allowed. However, additional components, changes to the power circuit, or mechanical modifications to the unit saddle or MCC exteriors must be approved by Schneider Electric. Contact your local Schneider Electric representative for more information.

If the unit is removable, follow the instructions below. If the unit is a fixed position unit, follow the instructions for Modifying Fixed Units.

Modifying Removable Units

  1. Turn off all power supplying this equipment before working on or inside the equipment and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm the power is off.

  2. Remove the MCC unit from the structure. See the procedure for Maintaining the Control Unit.

  3. Perform the required modifications. Use thread-forming screws to mount devices. Do not use bolts and nuts, as they could loosen over time and cause property damage or personal injury. The hardware must not extend beyond the back of the MCC unit saddle more than 0.25 in. (6 mm) or beyond the sides and bottom pan by more than 0.125 in. (3 mm).

  4. Maintain proper electrical spacings

    • Through air between live parts (301–600 V)-In motor control units: 0.375 in. (9.5 mm); in other MCC units: 1.0 in. (25.4 mm).

    • Over (insulation) surface between live parts (301–600 V)-In motor control units: 0.5 in., (12.7 mm); in other MCC units: 2.0 in. (50.8 mm).

    • Between live parts and grounded metal (0–600 V)-in motor control units: 0.5 in. (12.7 mm); in other MCC units: 1.0 in. (25.4 mm).

    Spacing values above can also be used at lower voltages. For conditions other than those noted, contact Schneider Electric. * in the unit.

  5. Use a vacuum cleaner to remove all debris left in the unit due to the modifications. Do not use compressed air to blow out the unit, because all debris may not be fully removed.

  6. Perform the recommended maintenance procedures beginning in Maintaining the Control Unit.

  7. Make sure that vertical bus closing plugs are in place (except for one plug where the MCC unit stabs on the vertical bus). If other vertical bus closing plugs are not in the proper position, make sure that all power is removed from the vertical bus and reinstall the vertical bus closing plugs.

  8. Use a megohmmeter to perform an insulation test as outlined in Insulation Test.

  9. Look for and clear any obstructions that does not permit proper energizing of the MCC unit.

  10. Reinstall the MCC unit and follow the procedures for Energizing the MCC.

Modifying Fixed Units

  1. Turn off all power supplying this equipment before working on or inside the equipment and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm the power is off.

  2. If drilling holes in the back of the MCC unit saddle is required, do not drill through the back of the saddle more than 0.1875 in. (5 mm). Use a drill stop device for this procedure.

  3. Perform the required modifications. Use thread-forming screws to mount devices. Do not use bolts and nuts, as they could loosen over time and cause property damage or personal injury. The hardware must not extend beyond the back of the MCC unit saddle more than 0.25 in. (6 mm) or beyond the sides and bottom pan by more than 0.125 in. (3 mm).

  4. Maintain proper electrical spacings

    • Through air between live parts (301–600 V)-In motor control units: 0.375 in. (9.5 mm); in other MCC units: 1.0 in. (25.4 mm).

    • Over (insulation) surface between live parts (301–600 V)-In motor control units: 0.5 in., (12.7 mm); in other MCC units: 2.0 in. (50.8 mm).

    • Between live parts and grounded metal (0–600 V)-in motor control units: 0.5 in. (12.7 mm); in other MCC units: 1.0 in. (25.4 mm).

    Spacing values above can also be used at lower voltages. For conditions other than those noted, contact Schneider Electric. * in the unit.

  5. Use a vacuum cleaner to remove all debris left in the unit due to the modifications. Do not use compressed air to blow out the unit, because all debris may not be fully removed.

  6. Perform the recommended maintenance procedures beginning in Maintaining the Control Unit.

  7. Use a megohmmeter to perform an insulation test as outlined in Insulation Test.

  8. Follow the procedures for Energizing the MCC.

Installing Additional MCC Units

DANGER
Hazard of Electric Shock, Explosion, or Arc Flash
  • Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E, NOM-029-STPS, CSA Z462, or local equivalent.
  • This equipment must only be installed and serviced by qualified electrical personnel.
  • Turn off all power supplying this equipment before working on or inside equipment.
  • Always use a properly rated voltage sensing device to confirm power is off.
  • Replace all devices, doors, and covers before turning on power to this equipment.
Failure to follow these instructions will result in death or serious injury.

  1. Turn off all power supplying this equipment before working on or inside the equipment and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm the power is off.

  2. Position the midshelf (see Shelf and Door Installation, A) in the appropriate area of the structure.

    NOTE: Arc-rated MCCs have a midshelf specifically designed for arc-rated MCCs (see Shelf and Door Installation). This midshelf includes arc pressure relief flaps and must be used when installing arc-rated MCC units to maintain the arc containment ratings.

    Shelf and Door Installation

    Shelf Installation Kit Parts

    Item

    Description

    		 Qty Assemble per
    A

    Shelf

    		 2*

    Steps 2 and 3
    D

    Flat head screws

    		 4

    Step 3
    F

    Unit door

    		 1

    Step 4
    H

    Round head Torx® screws

    		 4*

    Steps 4 and 5
    J

    Quarter turn fastener receptacle

    		 2*

    Step 5

    Midshelf for Arc-Rated MCCs

  3. Place the mounting foot (see Shelf and Door Installation, B) of the shelf into the mounting pan slots (see Shelf and Door Installation, C). Secure the shelf at the mounting foot end, the left side, and the right side with flat head screws (see Shelf and Door Installation, Detail A, D).

  4. Install the hinge leaves of the door (see Shelf and Door Installation, Detail A, E) into the hinge slots (Item G), which are on the structure corner channel. Fasten the hinge leaves to the structure corner channel using Torx head screws (see Shelf and Door Installation, H).

  5. Install fastener receptacles ( see Shelf and Door Installation Detail B, J) into the bracket slots (see Shelf and Door Installation, K) and fasten with Torx head screws (see Shelf and Door Installation, H).

  6. If a grommeted wireway barrier is supplied, locate the vertical wireway grommet (see Cutting the Vertical Wireway Grommet) nearest the bottom of the control unit. Cut the grommet following the instructions on the grommet. See the second paragraph under Load and Control Wiring.

    Cutting the Vertical Wireway Grommet (when supplied)

  7. Remove the manual bus shutter(s) (see Removing the Manual Bus Shutter) to allow insertion of the new control unit; slide out the top bus shutter.

    NOTE: Do not remove the tether.

    Removing the Manual Bus Shutter

  8. Insert unit into MCC as follows:

    All Units Except Compac 6 (six in. high) Units

    1. Confirm the cam mechanism is in the open position and the disconnect handle is in the off position; position the mounting slides of the control unit onto the slots of the midshelf. Slide the unit inward to engage the cam mechanism (see Engaging the Cam Mechanism).

      Engaging the Cam Mechanism

    2. Press the handles inward until they are flush with the face of the MCC (see Handles Flush with the Front of the MCC).

      Handles Flush with the Front of the MCC

    3. Turn the screw on the control unit lock-in panel (when supplied) located at the bottom front of the control unit (see Tightening the Control Unit Lock-in Panel), until the lock-in pawl is latched to the support shelf below the control unit.

      Tightening the Control Unit Lock-in Panel (when supplied)

    Compac 6 (six in. high) Units

    1. Position the mounting slides of the control unit onto the slots of the midshelf. Slide the unit inward until the unit is halfway in, then move it inward with a quick push. This movement easily overcomes the compression of the stabs as they engage the vertical bus (see Reinstalling the Compac 6 Control Unit).

      NOTE: The interlock is spring loaded and engages automatically when the control unit is inserted with a firm push to the operator handle. Pressing the structure interlock release is not necessary.

      Reinstalling the Compac 6 Control Unit

  9. Pull the power leads from the vertical wireway through the grommet and into the control unit.

    All Units Except Compac 6 (six in. high) Units

    1. Connect the power leads to the power terminals in the control unit (see Power Leads Connected to Power Terminals).

      NOTE: To provide additional working clearance, grasp the control station plate on the right side and pull gently, allowing it to hinge open (see Connecting Control Leads to the Terminal Blocks).

      Power Leads Connected to Power Terminals

    Connecting Control Leads to the Terminal Blocks

    Compac 6 (six in. high) Units

    1. Connect the power leads to the power terminals on the starter. Refer to the torque label on the right inside wall of the unit for load terminal wire and torque requirements (see Typical Unit Torque Label).

      Typical Unit Torque Label

      NOTE: Removal of the control station plate may be necessary to install power and control wiring. For detailed steps, refer to step 4 in Removing the Compac™ 6 Control Unit.

  10. Pull the control leads from the vertical wireway through the grommet and connect them to the terminals of the top (removable) portion of the control pull-apart terminal blocks (see Connecting Control Leads to the Terminal Blocks and Pull-apart Terminals).

    All Units Except Compac 6 (six in. high) Units

    Compac 6 (six in.) Units

    Pull-apart Terminals

    10 A Control Wire Terminal Block

    • To separate or remove the top portion of the terminal block from its base, grasp the top half and pull apart as shown.

    • Each terminal is rated for one 16-12 AWG wire or two 16 AWG wires.

    • Torque terminal screws to 5 lb-in. (0.5 N•m).

    NOTE: If removal of the control station plate was necessary, reinstall the plate by reversing the steps used to remove the plate (step 4 in Removing the Compac™ 6 Control Unit).

  11. Close the unit door and secure the fasteners.

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