Transformer min. clear distance

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Bernardoc

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Location
Florida
Occupation
Designer
We are working on an existing building, the transformer is 480 V, 215 kva and it is located next to the exist door, the inspector is asking to clear the transformer 3 ft. from the edge of the door frame, under code section 110.26 C 2A. But 110.26 Working Space "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 A2 and A3. My argument is that a transformer will not be energize if it need servicing, so the section will not apply. Does any body have an opinion.
 

augie47

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Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Locally the inspectors agree with your opinion ie: not subject to servicing while energized.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
I don't get it. 110.26 C 2A says nothing about clearances, C is just about entrance and egress, then (2) is only regarding 1200A and above and (a) just says "unobstructed".
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
As a design engineer, I only provide a minimum of 6" all around the transformer. That is for air circulation, not for working space. I do not consider a transformer to require work while energized.

The best argument I have heard for the opposite position is that you can't do thermographic inspections unless the item is energized. That opinion considers thermography as a means of "examination," a word that does appear in 110.26(A). I disagree with the opinion. You are "examining" the item at a significant distance; you can do thermography from inside the space normally occupied by the transformer's enclosure.
 
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