Dang old king
Member
Hollow: empty space ,void
50kva transformers and smaller are allowed in such areas.
Why 50kva limitation? Because the buildup of heat in such an unventilated area on higher rated transformers may cause them to fail and burn up.
Plenum: A compartment or duct to which one or more air ducts are connected and forms part of the air distribution system.
Although these areas may appear similar, they are two distinctively different portions of a building. A hollow space will not communicate to an environmental air passageway and likewise.
Electrical Equipment in Plenum?s: Must be of fire-resistant construction and of the ?Low Smoke Producing Type.
It is my contention that above grid return air plenums are a hollow space, but should not be considered as such, as they do indeed contain something:
Environmental air, The Article in 450 does not apply to transformers in environmental air, otherwise we would allow transformers to be installed in metal ducted plenums which are void and empty as defined by the term hollow. All equipment installed in return air above grid plenums must be rated for this purpose, not just electrical equipment.
Stalcup address it http://books.google.com/books?id=OkwGeMAXJa8C&pg=SA8-PA3&lpg=SA8-PA3&dq=transformers+installed+in+hollow+space&source=bl&ots=VGF24WbJ0T&sig=IoUrdqThUEkFw09h5QPHYlK5Vgk&hl=en#v=onepage&q=transformers%20installed%20in%20hollow%20space&f=false
Mike Holt address it http://forums.mikeholt.com/archive/index.php/t-120884.html?
The accessibility requirements prescribed in 450-13 are just that a matter of accessibility. If the hollow space communicates with and environmental air passageway, that hollow space now becomes an approved form of duct work as prescribed in the 03 International Mechanical Code. Which also address the installation of electrical equipment in environmental air return plenums in article 602.2.1.1 and then again in article 602.2.1.4 Article 300.22 applies to electrical equipment installed in environmental air plenums. The code writers intent in article 450.13 was to limit the size of a transformer based on its ability to dissipate the unwanted heat associated with transformers in concealed non ventilated space?s. Not to allow the installation of a piece of equipment in return air plenums. Although 300.22(C)2 address such applications and requirements. U/L and the President of IAEI has made information available to me ?Transformers are not tested for the plenum rating as the body of the code already address there installation in a hollow space? .
Herein lies the problem. What to do with a transformer in a plenum?
Does anyone out there read it the way I read it or am I all wet on this?
50kva transformers and smaller are allowed in such areas.
Why 50kva limitation? Because the buildup of heat in such an unventilated area on higher rated transformers may cause them to fail and burn up.
Plenum: A compartment or duct to which one or more air ducts are connected and forms part of the air distribution system.
Although these areas may appear similar, they are two distinctively different portions of a building. A hollow space will not communicate to an environmental air passageway and likewise.
Electrical Equipment in Plenum?s: Must be of fire-resistant construction and of the ?Low Smoke Producing Type.
It is my contention that above grid return air plenums are a hollow space, but should not be considered as such, as they do indeed contain something:
Environmental air, The Article in 450 does not apply to transformers in environmental air, otherwise we would allow transformers to be installed in metal ducted plenums which are void and empty as defined by the term hollow. All equipment installed in return air above grid plenums must be rated for this purpose, not just electrical equipment.
Stalcup address it http://books.google.com/books?id=OkwGeMAXJa8C&pg=SA8-PA3&lpg=SA8-PA3&dq=transformers+installed+in+hollow+space&source=bl&ots=VGF24WbJ0T&sig=IoUrdqThUEkFw09h5QPHYlK5Vgk&hl=en#v=onepage&q=transformers%20installed%20in%20hollow%20space&f=false
Mike Holt address it http://forums.mikeholt.com/archive/index.php/t-120884.html?
The accessibility requirements prescribed in 450-13 are just that a matter of accessibility. If the hollow space communicates with and environmental air passageway, that hollow space now becomes an approved form of duct work as prescribed in the 03 International Mechanical Code. Which also address the installation of electrical equipment in environmental air return plenums in article 602.2.1.1 and then again in article 602.2.1.4 Article 300.22 applies to electrical equipment installed in environmental air plenums. The code writers intent in article 450.13 was to limit the size of a transformer based on its ability to dissipate the unwanted heat associated with transformers in concealed non ventilated space?s. Not to allow the installation of a piece of equipment in return air plenums. Although 300.22(C)2 address such applications and requirements. U/L and the President of IAEI has made information available to me ?Transformers are not tested for the plenum rating as the body of the code already address there installation in a hollow space? .
Herein lies the problem. What to do with a transformer in a plenum?
Does anyone out there read it the way I read it or am I all wet on this?
