nvpowerdoc
Member
- Location
- Las Vegas, NV
Do the same working clearances apply to 600V nominal or less transformers as that of panels?
Situation: 300kVA dry-type 480V - 208Y/120V transformer installed in a fire rated electrical room under condition 2 (i.e., the distance from the face of transformer to a grounded wall).
The only article that specifically mentions transformers and accessibility (or there lack of) is 2002 NEC 450.12(A):Open Installations. Dry-type transformers 600 volts, nominal, or less, located in the open on walls, columns, or structures, shall not be required to be readily accessible.
Per 110.26(A), the working space for equipment operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the dimensions of 110.26(A)(1), (2), and (3) or as required or permitted elsewhere in this Code, may or may not apply.
The question is, does a transformer fall under "likely to require examination,...while energized"? And yes, I do know that folks take covers off transformers, the question is should it be done "energized"?
Could one post an "Arc Flash" label indicating "unsafe at any distance or Caloric protection while energized" prohibiting the opening of the transformer while energized?
Situation: 300kVA dry-type 480V - 208Y/120V transformer installed in a fire rated electrical room under condition 2 (i.e., the distance from the face of transformer to a grounded wall).
The only article that specifically mentions transformers and accessibility (or there lack of) is 2002 NEC 450.12(A):Open Installations. Dry-type transformers 600 volts, nominal, or less, located in the open on walls, columns, or structures, shall not be required to be readily accessible.
Per 110.26(A), the working space for equipment operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the dimensions of 110.26(A)(1), (2), and (3) or as required or permitted elsewhere in this Code, may or may not apply.
The question is, does a transformer fall under "likely to require examination,...while energized"? And yes, I do know that folks take covers off transformers, the question is should it be done "energized"?
Could one post an "Arc Flash" label indicating "unsafe at any distance or Caloric protection while energized" prohibiting the opening of the transformer while energized?
