Why 13?
A primer on how NFPA's sprinkler standard hooked up with an 'unlucky' number
NFPA Journal, July/August 2010
When Frederick Grinnell worked with a small insurance industry group to produce consensus regulations for the design and installation of sprinkler systems in 1896, it was a great moment in fire protection. Before that, sprinkler systems were installed using myriad pipe schedule and spacing arrangements, with a reported nine different standards in use in the Boston area alone. The success of the sprinkler system standardization effort led those pioneers to form an organization to continue the good work, the National Fire Protection Association.
Since the sprinkler standard actually predated NFPA, someone occasionally asks why the sprinkler system standard is NFPA 13, rather than NFPA 1. What is the significance? Furthermore, why did NFPA assign a number that is traditionally associated with bad luck in Western cultures?
Part of the answer is that NFPA didn’t assign the number and that the number 13 didn’t become associated with the sprinkler standard until 40 years after the original document was published.
The organization responsible for publishing the sprinkler rules in their early years was the National Board of Fire Underwriters (NBFU), an association of property insurers affiliated so strongly with Underwriters Laboratories that they once shared the same president. Those rules were called the Rules and Regulations of the National Board of Fire Underwriters for Sprinkler Equipment, Automatic and Open Systems, as Recommended by the National Fire Protection Association.
The NBFU didn’t introduce a number on the cover of the sprinkler rules until 1936, when the document was titled “NBFU Pamphlet No. 13.” The first use of the term “standard” appears to have been in the subsequent 1940 edition, titled NBFU Pamphlet No. 13—Standards of the NBFU for the Installation of Sprinkler Equipment.
Pioneers of Progress, a book written about the success of the NBFU from 1866 to 1941, included an appendix that described the NBFU organizational system and suggests that, by today’s nomenclature, the sprinkler standard would be more accurately described as number 1.3 or 1-3 rather than 13. The NBFU’s system for categorizing standards and recommended safeguards reserved Division 1 for fire-extinguishing appliances; Division 2 for fire-extinguishing auxiliaries such as pumps, tanks, and private fire brigades; Division 3 for flammable liquids; Division 4 for combustible solids; Division 5 for hazardous gases; Division 6 for explosive dust; Division 7 for electrical equipment; and Division 8 for construction. To a great extent, this organizational system is still evident in the numbers assigned to older standards such as NFPA 30, Flammable and Combustible Liquids Code, NFPA 70®, National Electrical Code®, and NFPA 72, National Fire Alarm and Signaling Code. Some major shifts in the numbering system have taken place over the years, such as the 1986 redesignation of NFPA 27, Industrial Fire Brigades, to NFPA 600.
In Category 1 for fire extinguishing appliances, the first subcategory was listed as “First Aid Fire Appliances.” This became 1-0 or 1.0 or, inexplicably, 10. The rules for sprinkler systems were listed fourth in this category, after those for foam and carbon dioxide systems, and were therefore published as NBFU 13.
In 1940, when the NBFU was still publishing NBFU 13, NFPA separately published a booklet containing both NFPA 13 and NFPA 13A, rules for sprinkler care and maintenance. While both organizations published the document for a number of editions, the last version of the sprinkler rules published under the NBFU banner was produced in 1964. Almost 50 years later, a reference to the NBFU is occasionally still found in project specifications.
Finally, for those concerned about the luck associated with the number of the sprinkler system installation standard, think of it as standard 1.3 rather than 13. Or simply consider all the good fortune it has brought over the years in terms of lives saved and property protected.
Russ Fleming, P.E., is the executive vice-president of the National Fire Sprinkler Assocaition and a member of the NFPA Technical Correlating Committee on Automatic Sprinklers.