1 May
2006
1 May
'06
3:47 p.m.
On May 1, 2006, at 11:51 AM, Lyle Bickley wrote:
Here's an interesting link on the subject. The
short of it the
origin of 19"
racks were as Telco switching "relay racks".
http://encyclopedia.thefreedictionary.com/19%20inch%20rack
And the rest of the story (so to speak) as to _why_ 19":
I asked a fellow "middle aged" phart who (also) worked with genuine
Bell System auld pharts to verify my memory of where this came from --
it was all a matter of convenience (and cost).
The engineering department (Bell Labs) planned equipment layouts
based on
a 24" grid system. To build the relay racks, channel iron 2.5" deep
(measured
on the outside) was used as it was very common and relatively cheap.
24 - (2.5*2) = 19 inches for the shelf space.
The above was designed for the first relay-based telephone switches.
Mike