Square D Model 6 MCC Midshelf Assemblies
A Square D Model 6 MCC midshelf is easy to overlook until the bucket does not fit.
The shelf has to match the lineup. Standard, Model 5 retrofit, arc-rated, auto-shutter, and CDR setups are not all the same.
Quick Midshelf Match
| Setup | Use it when | Watch for |
|---|---|---|
| Model 6 in Model 5 | Model 5 MCC made after May 1992 | Terminal block rail holes, side latch holes |
| Arc-rated Model 6 | Arc-resistant Model 6 section | Barrier flap / top bracket hardware |
| Arc-rated + auto shutter | Arc-rated section with automatic shutter | Shutter clearance and two-screw mounting |
| Standard Model 6 | Most regular Model 6 sections | Standard vertical bus closing plugs |
| Standard + auto shutter | Regular Model 6 with automatic shutter | Relief cutout for shutter travel |
1. Model 6 Unit in a Model 5 MCC
Used when a Model 6 plug-on unit goes into a Model 5 MCC made after May 1992.
Check for:
- Terminal block rail mounting holes
- Side latch mounting holes
- Model 5-style hardware layout
Why it matters: Model 5 units did not use the same saddle bottom plate setup as Model 6 units.
2. Arc-Rated Model 6 Midshelf
Used in Model 6 arc-resistant MCCs without auto shutter.
Check for:
- Arc-rated label
- Barrier flap hardware
- Top bracket assembly
Do not treat arc-rated hardware like standard hardware. The shelf is part of the arc-rated setup.
3. Arc-Rated Model 6 With Auto Shutter
Used when both are true:
- The MCC is arc-rated
- The section has automatic vertical bus shutters
The shutter mounts beside the midshelf and fastens with two screws. The shelf must clear the shutter and still match the arc-rated construction.
4. Standard Model 6 Midshelf
This is the common one.
Used for:
- Standard Model 6 sections
- Standard vertical bus closing plugs
- CDR units, meaning closed-door racking
Do not confuse CDR with auto shutter. They are different options.
5. Standard Model 6 With Auto Shutter
Used for standard Model 6 sections with the automatic vertical bus shutter option.
Check for:
- Shutter mechanism beside the shelf
- Relief in the shelf for shutter movement
- Two-screw shutter attachment
If the shutter is there, use the auto-shutter shelf.
Send These Photos Before Ordering
Send photos of:
- MCC nameplate
- Bucket opening
- Existing midshelf
- Door and handle
- Latch area
- Auto-shutter hardware, if present
- Arc-rated labels, if present
Email sales@mccdepot.com or call 307-442-0382.
Bottom Line
Before ordering a Model 6 midshelf or replacement bucket, confirm:
- Model 5 or Model 6
- Manufacture date
- Arc-rated or standard
- Auto shutter or no auto shutter
- CDR or no CDR
Need help matching it? Start with Square D Model 6 replacement buckets or bucket identification help.
Safety Note
MCC work should only be done by qualified electrical personnel. Follow lockout/tagout and site safety rules.
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