Transformer clearance

[paul]

I have a 480 to 120/208 75KVA xfmr installed. However, a 400KW generator was placed 6" too close to the xfmr. I have 6" behind the xfmr to the brick wall. Nameplate says on the front to allow that 6". I have a call into the Sq D rep right now to see if we can vent it another way so I can put it all the way up against the wall. Is there any way I can get around 110.26 to make this legal? Otherwise I have to move it to another spot, which requires ALOT of work and a night cutover at my expense.

Any help would be much appreciated.

 

[charlie b]

Re: Transformer clearance

I would not advocate anything that ?gets around? a requirement that has a direct impact on personnel safety. The Square D rep might be your best bet. Perhaps they can retrofit another vent on a different side.

But who put the generator in the way? If not you, then any changes should be at their expense.

 

[paul]

Re: Transformer clearance

Originally posted by charlie b:
But who put the generator in the way? If not you, then any changes should be at their expense.

GC provided and installed the genset, but it's all part of the same job. I was first in with the transformer, but that is to little avail. Bottom line, my fault as I didn't even realize it before energizing and transfering existing loads. Transformer is easier and less expensive to move. Genset is going to stay put.

 

[iggy2]

Re: Transformer clearance

You probably cannot make the existing ventilated one comply, but is it easier/cheaper to change the transformer out to a non-ventilated type? At least then you would not have to relocate it....

 

[paul]

Re: Transformer clearance

After thinking it over and consulting with another, I believe I'll rotat the transformer 90 degrees. I don't believe I'll have any issues if I do this. Here's a pic with the genset hidden.

 

[caj1962]

Re: Transformer clearance

Just curious but does the transformer impede on another pice of electrical equipment that would need to be examined while energized? If not then I would say leave it alone, there is no way you should take that cover off while the transformer is energized. Just HMO of course.

(A) 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), (2), and (3) or as required or permitted elsewhere in this Code.

 

[steve66]

Re: Transformer clearance

I am not sure everyone agrees that transformers are "likely to require... while energized". Why would a "step-back" space (like that required by 100.26) apply to a suspended transformer? If it doesn't apply to a suspended transformer, why would it apply to one on the floor?

See 450.13.

Steve

 

[rb]

Re: Transformer clearance

I received an opinion from NFPA a couple of years ago that said a transformer does not require servicing or adjustment while energized.

 

[charlie]

Re: Transformer clearance

Rb, as you have stated, it is indeed an opinion. It carries no more weight than an opinion you get right here. The exception is if you get a formal interpretation from the NFPA. Along that same line, Indiana has removed the NFPA and inserted the State Building Commission as the interpreter of the Code and the final authority. I suspect some other jurisdictions have done the same thing. Check your local Codes.

 

[tom baker]

Re: Transformer clearance

Whats the voltage? If 480 its 42" to conductive parts and 36" to insulated parts.
I installed an MCC once and it was 20" deep instead of 15" I was 6" too close to a 12" water elbow to a fire pump. I checked with the AHJ, and he allowed me to put an insulating cover on the elbow. I had a boat cover mfg make an red insulating cover or herculite. I wrapped the elbow with sheet rubber to be extra safe.
So could you insulate the generator with some rubatex foam?