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Will the current model plug-in units install into the older I Line busway?

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At one time, I-Line plug-in units were offered either with or without a grounding provision to match the integral ground bus.  The integral ground bus was itself an optional feature on early series of I-Line busway.  Today, all plug-in units ship with this grounding provision, and in some instances, it will be necessary to remove the ground stab on the new plug-in unit in order to install it on certain older busway.


The following fusible busway plug-in units are obsolete, and they are replaced by the a new unit with the same catalog number plus the addition of a "G" suffix; however, there are circumstances, outlined in notes below, which may require additional attention for a successful installation.
PQ3203, PQ4203, PQ3603,PQ4603
PQ3206, PQ4206, PQ3606, PQ4606
PQ3210, PQ4210, PQ3610, PQ4610
PQ3220, PQ4220, PQ3620, PQ4620
PS3220, PS4220, PS3620, PS4620
PBQ3240, PBQ4240, PBQ3640, PBQ4640
PBQ3260, PBQ4260, PBQ3660, PBQ4660
PTQ3680, PTQ4680
PTQ36100, PTQ46100
PTQ36120, PTQ46120

  • New 800A or larger plug-in units cannot be installed on Series 1 I-Line busway.  These newer 800A and larger plug-in units have catalog numbers beginning "PTQ" and utilize a bolted connection to busway, requiring the removal of the plug-in base on the busway to make the connection.  Series 1 I-Line busway does not have a removable plug-in base, and therefore cannot be fitted with these 800A and higher "PTQ" plug-in units.
  • The catalog numbers for 800A - 1200A  plug-in units today require, in addition to the "G" suffix, a final "H" suffix for horizontal applications or a final "V" for vertical applications.
  • Today, all plug-in units come with a ground stab, which is designated by a "G" suffix in the plug-in unit catalog number.  In some instances, it may be necessary to remove the ground stab in order to install the new plug-in unit on older I-Line busway.
  • When replacing a plug-in unit removed from a run of Series 1 I-Line busway, it is necessary to remove the ground stab on the new plug-in unit prior to installation.
  • View the plug-in opening on the busway.  If it has four large openings and also a smaller opening in the upper right hand corner, the new plug-in unit will be a direct replacement.  If there is no smaller opening in the upper right hand corner, the installer must remove the ground finger (stab) on the back of the new plug-in unit prior to installation.
  • When installing a new plug-in unit on older busway, a large instruction label on the top of the plug-in unit indicates that the plug-in unit hanger on the right side of the device (when viewed from the front of the device) should align with a notch on the top rail of the busway.  The hanger on the left side of the plug-in unit will NOT align with a notch.  The older series of plug-in units had different alignment arrangements.
  • Older 240V rated plug-in units rated 400A and 600A must be replaced with new 600V rated devices, and the fuse spacing in the new device must be changed in the field to accommodate 240V rated fuses.  This is accomplished by relocating the load side fuse base, a procedure for which is included in the instructions shipped with the new plug-in unit.
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