Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!bionet!hayes.fai.alaska.edu!accuvax.nwu.edu!nucsrl!telecom-request From: haynes@ucscc.ucsc.edu (99700000) Newsgroups: comp.dcom.telecom Subject: Re: 19" Rack Format Message-ID: <13127@accuvax.nwu.edu> Date: 7 Oct 90 18:48:30 GMT Sender: news@accuvax.nwu.edu Reply-To: Jim Haynes Organization: University of California, Santa Cruz CATS Lines: 37 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 719, Message 3 of 8 Let's get nit-picky about trivia. :-) In article <13072@accuvax.nwu.edu> 0004133373@mcimail.com (Donald E. Kimberlin) writes: >you have need for specifications in the U.S., the Electronic >Industries Association (EIA) published a standard many years ago. If I remember from an old issue of the Radio Amateur's Handbook that there was at one time both a Western Electric 19" standard and a RETMA 19" standard. RETMA (well before that it was RMA - Radio Manufacturers' Association - was the predecessor name to EIA) The WECo standard was strictly multiples of 1-3/4" panels with notches 1/4" in from the edges: so the holes are spaced 1/2; 1-1/4; 1/2; 1-1/4; 1/2 and so on. The RMA standard had additional holes in the iddle of the 1-1/4" intervals. So most racks you get today have a spacing 1/2; 5/8; 5/8; 1/2; 5/8; 5/8; 1/2 and so on. >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 don't know about the 30 and 36 inch stuff; but the Bell 23-inch racks have a standard based on 2-inch vertical increments; or maybe it's integral multiples of 1 inch. I belive the EIA standard also allows for a 24-inch rack, as I've seen some of those in catalogs. I'm dubious about any Western Union connection with all this, because I've seen some Western Union equipment that doesn't fit on 19" racks. But I'm equally eager to learn the True History of this peculiar 19" dimension that has ruled the lives of so many of ur for so long. haynes@ucscc.ucsc.edu haynes@ucscc.bitnet ..ucbvax!ucscc!haynes