The paragraph above is extracted from NFPA-13, 2010.
220.127.116.11 (highlighted in yellow). To put things in context, this paragraph is tucked away on page 209 (Chapter 21) of the code. The code is approximately 400 pages long. It is "extracted" from NFPA 75 - 2010 Standard for the Fire Protection of Information Technology Equipment; perhaps as a convenience.
In the 2013 edition of NFPA 75, the paragraph is located in Chapter 22 as 18.104.22.168. A couple of clarifications were introduced as follows:
Other than the few exceptions introduced in 2013, the requirements are clear: You must provide a fire protection system below a raised floor and you have three options to pick from.
So whether you agree or disagree, these few paragraphs are embedded into NFPA 13 and hence the safest bet would be to assume that they are enforceable by the Authorities Having Jurisdiction (AHJ) unless proven otherwise! Designers, owners, and operators need to be aware of that.
Hopefully combustible material is not stored below raised floors, but beyond that, I have some questions that I cannot but ask:
- I don't see a height requirement of a raised floor specified in the code. I can understand a 3 or 4 foot raised floor, but would a 12" still require it? Who makes that judgement?
- Cable trays are often installed below raised floor, how is sprinkler coverage affected? What/where is the guideline to design a sprinkler layout with cable trays as obstructions?
- Are local AHJs enforcing this?
- How many manufacturers make sprinkler heads that are approved for such concealed spaces?
- In a dynamic environment like a data center where you always have folks pulling cable or modifying what is already installed, is a more hazardous condition being created by introducing water piping below the floor?
- Would signage be required on the floor indicating locations of sprinkler heads?