We are installing a 75kva transformer in a ceiling on a building upright pole and the local maintanence tech is welding up a stand to set the transformer on. It weighs just under 600lbs....Im sure he is just "guessing" at the structural design. Are most installations done like this, or, are they engineered?
Are dry type interior transformer stands structuraly rated?
- Thread starter Mule
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If I read your post right, your installing a 75kva transformer in a ceiling on a welded support. I would recomend that an engineer look and sign off on or design the support for this item. On a side note, you said your installing this in a ceiling. Check 2005 NEC art 450.13 (B) - prohibits the installtion of transformers in hollow spaces if over 50kva.
if it fails and injures or kills someone, your behind is on the line. . . so if there is an engineer on record for the job, send him a sketch of your intended design for review to relieve some of the liability. if you can figure out the design yourself, just allow a safety factor of two. jmho
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
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- Electrical Contractor
Not a good start. Obviously, we agree with that. I'd be leery about engineering support of 100lb overhead. Then again, I've never welded.
I'd insist that the support and its engineering seal be a package, without you in the middle. Make sure its attachment to the post is included.
charlie
Senior Member
- Location
- Indianapolis
I am concerned about part of Kevin's post that seems to be ignored. 450.13(B) Hollow Space Installations. Dry-type transformers 600 volts, nominal, or less and not exceeding 50 kVA shall be permitted in hollow spaces of buildings not permanently closed in by structure, provided they meet the ventilation requirements of 450.9 and separation from combustible materials requirements of 450.21(A). Transformers so installed shall not be required to be readily accessible.
It is obvious that the CMP is concerned about larger transformers installed in that position. You have a problem with ventilation, combustible materials, weight of the transformer, and probably the clearance requirements of 110.26. If you are insistent on doing this, I would definitely get an engineer's seal on a drawing plus the AHJ's blessing before proceeding. :smile:
This is a commercial building with a average ceiling height of 20-32ft. We are not installing it above a ceiling....or maybe I should have used the term "roof" instead of "ceiling"
The stand is not in my scope of work.....the client (maintenance tech) is installing the support...so I cant be responsible for it, I only supplied the physical dimensions and weight requirements.....However, you have raised a issue in my mind....THEY should set the transformer, NOT ME, because if I did it, I, set it on a un-sufficent, or underdesigned stand, leaving me liable
So, Im focusing on, "are these installations usually installed without engineering, or with?".......What's your experience?
The stand is not in my scope of work.....the client (maintenance tech) is installing the support...so I cant be responsible for it, I only supplied the physical dimensions and weight requirements.....However, you have raised a issue in my mind....THEY should set the transformer, NOT ME, because if I did it, I, set it on a un-sufficent, or underdesigned stand, leaving me liable
So, Im focusing on, "are these installations usually installed without engineering, or with?".......What's your experience?
mdshunk
Senior Member
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- Right here.
I say, wait and see what he comes up with. It may end up being something you could place a Sherman tank on. You might be worrying for nothing. On the other hand, if you have doubts, just do everything but place the transformer until you can get someone, other than you, to officially deem the rack suitable for that transformer.
Pierre C Belarge
Senior Member
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- Westchester County, New York
Fulthrotl
~Autocorrect is My Worst Enema.~
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- E
it's funny what concerns pop up in different people's minds.... on person
can be saying.... "not a problem, do it all the time", and another person
can say about the same thing "ACK!!!! RED ALERT! WE'RE ALL GONNA DIE!!"
most transformers can be ordered with factory designed wall mounts,
usually two big #12 mild steel angles that bolt to the transformer chassis
and have a couple 1/2" holes on the wall side to bolt to the wall...
i've seen 1 5/8" strut with a strut strap the size of the column, top
and bottom of factory mounts, so you've got a 600 lb load hanging
by two strut straps..... :-?:-? in california, no less....
i guess there are engineers mainly 'cause otherwise there are people
who think the following design is just fine...
As for that upper shelf, I think I could do better than that ! and I a "mud dobber" at best......:grin:
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
I am not sure if an electrician built these or someone else.
"Pretty is in the eye of the beholder"
"Pretty is in the eye of the beholder"
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