workspace clearances

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Jhaas5@nycap

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Location
Albany NY
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electrician
i have a clearance issue that is probably not an issue. I have 2 480v transformers installed across from one another sharing the same workspace. that work space is 42" deep from opening to opening. an engineer has stated the requirement of 126(a)1 dictates a condition 3 requiring 48". he used an exhibit from the handbook 110.12 showing two switchboards across from on another stating they are both considered exposed electrical equipment........ By the nec definition wouldn't they be considered "Enclosed" electrical equipment, therefor making them simply a grounded surface. Follow up, isn't it about time we defined a transformer as a non serviceable piece of electrical equipment? The clearance issue has been a problem for my entire 30 year career and still remains open to opinions that differ widely.
 
Yes, opinions differ widely. My opinion is that transformers do not fall under the working clearance requirements of 110.26. I believe you only need 6" all around the transformer to allow for heat dissipation.

I acknowledge that others will say that thermographic inspections of the transformer windings must be done live, would constitute "requiring examination while energized," and would therefore bring 110.26 into play. I disagree, and will offer my (admittedly weak) reasoning that you are looking at, but not touching, the inside of the transformer enclosure.
 
I thank you for the quick response. I have received the same perceived understanding of the code from all electricians and AHJ officials that I have posed the question to. Wish the NFPA 70 would address it. also its always been my understanding we can remove covers and visually inspect but "breaking the plane" is what constitutes work, servicing or maintenance. Additionally, we are all becoming familiar with very stringent commissioning procedures after the TTR tests are completed, Megger test are performed, Torques are done and recorded. Upon commissioning the transformer we close the transformer open the secondary main and voltage check is done at the first disconnect, never done at the transformer. No one should ever have a reason to "break the plane" on an energized transformer. Seems like proper procedure ensures transformers are not serviceable.
 
I agree with Charlie since you have two transformers the working space requirement is not applicable. If it did apply it would be condition 3.
 
Jhaas5@nycap said:
..........................................................The clearance issue has been a problem for my entire 30 year career and still remains open to opinions that differ widely.
Click to expand...

and, as you state, unfortunately it will remain a grey area until some official document addresses transformers.
I agree with charlie-b (Post #2) but, all our posts will be opinions.
 
ok guys thanks for your input. Tell me if i'm crazy on this....... transformers have their own article 450. within the article 450.13 Accessibility is the only reference to space and clearances we need to maintain ventilation and distance from combustibles. no reference to other articles in the code or to 110.26 and no other article calls out a transformer. Therefore i have no need to follow any other requirements. If i go to 408 Switchboards, switchgear, and Panelboards. 408.2 specifically instructs me to follow other articles that apply. Am I crazy or does on this or am I simply supposed to follow the article on transformers for my transformer installs? No referance to workspace is intentional because there is no requirement?
 
Try not to overthink this. 110.26 stands by itself; no other article need be consulted. It requires working clearance for anything that requires maintenance (or certain other tasks) while energized. So it boils down to whether a transformer meets that description. I have already stated my opinion that it does not.
 
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