George, some of our electrical equipment (IEC950) is installed in an air
handling space (so called plenum). Our understanding is that UL has a
special test for smoke emissions so special plastics are required. Because
of that, we decided to use metal enclosures. We have to ensure that there
are no openings and that all cables entrances use special fittings for the
purpose. Usually, our equipment needs ventilation so we have to provide
metal air ducts from the ceiling to the equipment. In the end, the
construction is such that we don't need to have a UL rating for this use. It
is obvious from the construction that it complies so the electrical
inspectors allow it.
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From: Sparacino,George [SMTP:[email protected]]
Sent: Wednesday, April 14, 1999 3:27 PM
To: [email protected]
Subject: Enclosures rated for..
Hello Group,
I got a request to have our future open class controller products
"Plenum
Rated". In doing so, we could advertise that the product can be
installed
in a plenum.. the dead space above a drop ceiling to be exact. The
controllers are housed in a plastic (polymeric) enclosure.
So far, I found UL test requirements (UL935) for electric lighting
ballast's
that are to be installed in a similar space. These requirements are
extracted from the NEC and pertain to smoke and fire (flamespread).
I
haven't found a specific UL (or any other) document that encompasses
enclosures in a plenum specifically for the purposes of marking. I
have
seen specific requirements for wire & wiring (cabling).
If anyone in the group is familiar with the criteria for "Plenum
Rated"
Enclosures, I would like to know if I'm on the right track. Also, if
you
know of any more requirements or a specific standard(s) that would
apply,
please enlighten me.
Thanks,
George
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