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Electrical

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Hunterw23

Hunterw23

Electrical
Feb 23, 2023
1
I have a lineup of 4160V switch gear and we are installing 480V switch across from it. According to table 110.34(a) in the NEC handbook there should be a minimum of 5ft between them. Since this is an existing building and the switch is going to be new is there an exception that it can be less than 5ft for medium voltage? I know for low voltage there is an exception but I cannot find one for medium voltage.
 
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Exception based on what? No NEC exception that I'm aware of.
 
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Do you plan on having doors open and exposing live MV parts? 5ft is Condition 2, usually if there will not be exposed live parts, it is Condition 1, which is 4ft.

If you do plan on having live MV parts exposed when the doors are open, are the live parts themselves set back inside the gear? The measurement for Condition 2 is FROM the live parts, not the door of the gear.

What is the LV equipment? Could it be ordered in a fiberglass enclosure? That would not be “grounded”, so even if you plan on exposing the MV live parts, you would be back to Condition 1.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
 
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Rule of thumb, if the inspector measures the available clearance it isn’t enough.

I’ll see your silver lining and raise you two black clouds. - Protection Operations
 
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