#194 TIA-942 Tier III ceiling and cable trays, above or below?

Deborah MacPherson Wed 23 Jul 2014

I have a question about physical infrastructure in a TIA-942 Tier III data center.

A hospital has a few entire floors dedicated to mechanical chillers, electrical sub-stations, telecommunications, several building systems including the main data center.

A raised access floor is not used in this data center, all cabling needs to be above. Right or wrong, currently no ceiling is planned. If a ceiling is to be installed later, to establish a conceptual datum or clear zone today, should the cable trays be above or below the ceiling?

I cannot find a clear recommendation in TIA-942.

On the one hand cable trays below the ceiling may be dust collectors, on the other hand if there needs to be continual access to the cable trays, maybe the ceiling access panels will end up not being replaced every time and the trays should just be below.

Even though this is a physical architecture question rather than data architecture this forum is about, any recommendations are sincerely appreciated.

Thank you,.

Jose Gonzalez Thu 31 Jul 2014

Hi Deborah,

I have seen it done either way, a factor to consider is the clearance above the drop ceiling an how comfortable would it be to work on it. If it is not adequate then placing them below the drop ceiling line would be a better choice. But again there is no rule and you may even end with a combination, some above(main carriers) and some below(rack distribution). Hope this helps!

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