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S A F E G E A R ® M O T O R C O N T R O L C E N T E R /A R C - R E S I S TA N T M E TA L - C L A D C O N S T R U C T I O N
23
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Plenum installation
General instructions
Refer to the specific applicable General Arrangement and Floor Plan drawings for the plenum location. Follow
the specific applicable plenum routing shown on the floor plan. Instructions are the same for 1200, 2000,
3000 A main bus.
1.
Install plenum sections on MCC roof as shown on the General Arrangement drawing. Each section is bolted to the
roof base and also to the adjoining plenum section.
2.
Install additional plenum sections for venting outside of the building, in accordance with the field boundary. See
Figure 4 and 5.
3.
As each section installed is supported by the adjoining section and roofs, start with the first plenum section. The
plenum bases should be able to support the weight of each section, in accordance with local building code
requirements.
4.
The exhaust vent section, shown in Figure 3, should be installed in the building wall and connected to the last
plenum section as shown in Figure 4. The opening of the exhaust vent section cannot be installed pointing
upwards due to environmental considerations.
5.
The area outside the plenum exhaust vent needs to be kept clear of personnel and equipment due to the potential
for pressurized exhaust gasses that would be expelled in the area in case of an arc fault in the MCC. Specifically, a
horizontal cylindrical volume, with an 8 foot diameter, centered on the plenum exhaust vent and extending out 15
feet, as shown in Figure 5, needs to be clear all the time.
6.
Ensure that all bolts are correctly installed; a wrong assembly could allow toxic gas to escape through any given
space left.
7.
Do not remove exhaust mesh; incandescent particles might go outside the MCC in case of an arc fault.
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01
Plenum sections
Vent mesh
Exhaust
Two-sections plenum
End cover
One-sections plenum
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