Floor Mounted XFRMRS

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GoldDigger

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raberding said:
i think that 50 kva and above are not allowed above a ceiling...450.13
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There is room to argue about whether a transformer can be mounted directly from a ceiling rather than a wall, floor or column based on 450.13, but I read it as permitting that type of mounting as long as it is still readily accessible (i.e. no ladder or scaffolding required, etc.) As long as it is readily accessible it can be mounted anywhere that properly supports it.
But mounting, even attached to the wall, above a drop ceiling falls under the "hollow spaces not permanently closed in by structure" provision of (B), which limits the size to 50kva.
 
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GoldDigger

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mstrlucky74 said:
Im def not referring to above hung ceiling? Exposed!
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In that case you do not have to worry about the 50 kVA limitation of 450.13(B).
You only need to make sure that it is readily accessible for inspection (not for maintenance though), according to the full standard definition. That would mean to me that it could not require a ladder to access it. I hope it is a low ceiling and you can do all necessary inspection, including reading the nameplate, standing on the ground.
If you floor mount a dry transformer, you are not required to have it readily accessible for inspection, by the provisions of 450.13(A).
In all cases you would still have to meet the clearance requirements (including any clearance above) which are part of the transformer specifications.

PS: To me, the requirement for readily accessible for inspection may still be met if the transformer is ceiling mounted, but extends down close to the floor. But that may not play for an inspector.
 
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iwire

iwire

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You guys ever been to a Home Depot or Lowes?

The transformers are at the roof deck, clearly you need a ladder or lift to access them.

The only issue as they get larger is the weight and if the building structure is designed to support it.

Often they add steel to the trusses for us to hang them from.
 
masterinbama

masterinbama

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iwire said:
You guys ever been to a Home Depot or Lowes?

The transformers are at the roof deck, clearly you need a ladder or lift to access them.

The only issue as they get larger is the weight and if the building structure is designed to support it.

Often they add steel to the trusses for us to hang them from.
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And those are quite often 112.5 KVA units that weight about 1000 pounds.
 
kwired

kwired

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masterinbama said:
And those are quite often 112.5 KVA units that weight about 1000 pounds.
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And if the roof designers know this weight is going to be there they can design it to be able to handle it. 1000 pounds is not all that much weight for a roof, but the weight may need to be distributed over a certain area and not just all from one location.
 
infinity

infinity

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iwire said:
You guys ever been to a Home Depot or Lowes?

The transformers are at the roof deck, clearly you need a ladder or lift to access them.

The only issue as they get larger is the weight and if the building structure is designed to support it.

Often they add steel to the trusses for us to hang them from.
Click to expand...

I agree, we hang 75 Kva's all of the time often 10' or more above the floor. Regarding NYC there is nothing in the NYC Electrical code to prohibit hanging large transformers.
 
weressl

weressl

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GoldDigger said:
There is room to argue about whether a transformer can be mounted directly from a ceiling rather than a wall, floor or column based on 450.13, but I read it as permitting that type of mounting as long as it is still readily accessible (i.e. no ladder or scaffolding required, etc.) As long as it is readily accessible it can be mounted anywhere that properly supports it.
But mounting, even attached to the wall, above a drop ceiling falls under the "hollow spaces not permanently closed in by structure" provision of (B), which limits the size to 50kva.
Click to expand...

450.13 (B) Hollow Space Installations. Dry-type transformers
1000 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. [ROP 9?135]
 
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templdl

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Wisconsin
wirebender said:
What are the advantages of hanging them?
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If you don't want them on the floor which takes floor space and may not be convenient, you could use wall mounting brackets but then there must be a wall conveniently available and the also a weight limit which I forget what that is, then you can hang it using unistrut designing to support of the transformer or construct a platform. I've seen decks constructed also.
 
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mstrlucky74

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NJ
infinity said:
I agree, we hang 75 Kva's all of the time often 10' or more above the floor. Regarding NYC there is nothing in the NYC Electrical code to prohibit hanging large transformers.
Click to expand...

But what about it having to be readily accesible for inspection...no ladders etc.?
 
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