75kva Dry type secondary Transformere clearences

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DEMASTER0524

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Okay, I'm on a job that is requiring us to wall mount a 75kva dry type transformer above another dry type transformer. I have been looking for clearances that are permitted but the only thing I can find is a 12 inch clearance for fire ratings, and a 6 inch clearances as long as it has fresh air ventilation. I was wondering if there are any other clearances that will dictate how far apart I mount this transformer from the other one?
 
According to 450.9 the ventilation should be clearly marked on the trany. I guess you go with what they gave you but I would tend to give more room than 6"
 
DEMASTER0524 said:
Okay, I'm on a job that is requiring us to wall mount a 75kva dry type transformer above another dry type transformer. I have been looking for clearances that are permitted but the only thing I can find is a 12 inch clearance for fire ratings, and a 6 inch clearances as long as it has fresh air ventilation. I was wondering if there are any other clearances that will dictate how far apart I mount this transformer from the other one?
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Simple clearance is one thing but the lower transformer will heat the air which will rise to the transformer located about which may cause the transformer located about to run warmer. This may not be an issue but never the less should be considered..
 
DEMASTER0524 said:
Okay, I'm on a job that is requiring us to wall mount a 75kva dry type transformer above another dry type transformer. I have been looking for clearances that are permitted but the only thing I can find is a 12 inch clearance for fire ratings, and a 6 inch clearances as long as it has fresh air ventilation. I was wondering if there are any other clearances that will dictate how far apart I mount this transformer from the other one?
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What about 110.26? Wouldn't these general requirements apply?
 
electrofelon said:
What about 110.26? Wouldn't these general requirements apply?
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110.26 applies to everything electrical, including the recpts required by 210.52(B) in your kitchen, which are in violation of 110.26. It's kinda the NEC version of the time traveller paradox where one tries to kill one's own grandfather....


450.13 says it is okay to stack transformers.
 
We stack them fairly often in new construction due to the fact the architect does not provide enough room to do otherwise.

We usally leave about a foot between them. I suspect they do fine because they are often under loaded anyway.
 
iwire said:
We stack them fairly often in new construction due to the fact the architect does not provide enough room to do otherwise.

We usally leave about a foot between them. I suspect they do fine because they are often under loaded anyway.
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Even though I pointed out my concern I have not ever received any feedback where stacking transformers was an issue. The installer must be aware the the transformer mounted about would be installed in an ambient temperature that is higher which most likely is if no consequence but should never the less be considered.
 
Look up the transformer specs online. For some reason they forgot to stick an installation guide in the last transformer I bought, but the specs were readily available when I looked for a manual on the internet.

If I couldn't find anything out, I would use 6" minimum.
 
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