0004133373@mcimail.com (Donald E. Kimberlin) (10/07/90)
Responding to: Klas Nordstrom <radar@cd.chalmers.se> In Digest V10, Iss709, Klas asked: >When and by whom was the 19" rack standard invented ? I cannot speak about international standards on this matter, but if you have need for specifications in the U.S., the Electronic Industries Association (EIA) published a standard many years ago. If my fading memory is correct, its title is RS-170. You can get a copy for a modest fee from: Electronic Industries Association 2001 Eye Street Northwest Washington, DC 20006 Tel: +202 457 49 66 Be certain to verify the number of the standard before buying on my say-so. The title of the correct one will be self-evident. As a matter of interest, you will be surprised to see how many manufacturers violate the standard in various details. If you have been engaged in rack-mounting equipment of various vendors, it is not at all unusual to have to perform some hacksaw, hammer and file surgery in the process. Klas further asked: >I do not know if this is the right forum to ask this question but >since the telecom history goes back more than 100 years it is worth a >try. I cannot speak to the issues of what corner of history this method came from, but have reason to believe it predates the Bell hegemony, dating back to days of peak Western Union influence. BTW, 19 inches is not the only "standard." Bell electronics equipment most commonly uses 23 inch racks, while "frames" of electromechanical switching equipment mount in 30 or even 36 inch widths, all using the same 1-3/4 inch vertical increments. I do know the US inch-dimensioned racks all have whole-unit metric equivalents. Because the inch-dimensioned racks do not actually come out to exact inches, the root might well be some European imports of antiquity that set the norm for the US. Any technology historians out there for this one? <Any educators need something to put a grad student to work on?>