Stan Hoeppner wrote:
Boyd Stephen Smith Jr. put forth on 1/14/2010 12:13 PM:
[2] I usually estimate that a "U" is about 1.5 in. or 37.5 mm.Your estimation is wrong. One EIA/TIA Rack Unit, or "U", is exactly 1.75". It was defined in standard EIA-310-D in 1992, has been with us for 18 years now. There shouldn't have to be any guess work or "estimating" involved here. ;)
That's probably one of the more recent standards, but the 19 inch rack has been around for close to a century, having started life in the telephone business. More than thirty years ago, I was working on 1946-designed 19 inch rack gear.
-- Joe