The u space starts and stops in the middle of the 1 2 holes.
19 inch rack hole spacing.
Racks are divided into regions 1 75 inches in height within which there are three complete hole pairs in a vertically symmetric pattern the holes being centred 0 25 inch 6 4 mm 0 875 inch 22 2 mm and 1 5 inch 38 1 mm from the top or bottom of the region.
Horizontal spacing of vertical rows is specified by eia 310 at 18 5 16 18.
The whole spacing alternates at 1 2 5 8 5 8 and then repeats.
The term 19 inch comes from the width of the front panel of the boxes that are installed in the rack see the image below.
The rack unit is a measure of vertical spacing and is common to both the 19 and 23 inch racks.
Preceding unsigned comment added by 194 237 142 21 14 36 20 september 2010 utc.
This specification standardizes several important features of 19 racks such as the rack unit ru or u vertical hole spacing horizontal hole spacing rack opening and front panel width.
The specification also sets tolerances on each of these dimensions.
Eia 310 also sets the specifications for the hole spacing both vertically and horizontally of rack units within racks and cabinets.
The hole spacing for standard 19 inch racks on the mounting flange is spaced in groups of three holes.
Rack hole spacing for rack unit mounts.
All racks used for n series storage system installation must conform to the specifications in this section.
The funny thing is.
Vertical hole spacing is defined as a repeating pattern of holes within one rack unit of 1 75.
19 rack 18 5 16 18 312 465 1 mm.
Both the ibm 7014 model t00 and model t42 and the ibm 2101 model n00 racks conform but some other racks including a few from ibm do not.
To determine if your rack is a 19 rack measure the hole to hole spacing.
The eia 310 specification has been the 19 racks standard for equipment for 50 years.
Rack nuts are not standard.
Nothing on a 19 rack measures 19 inches.
Do not mix etsi 500 mm wide rack 515 mm between mounting holes with 23 inch rack.
The rack or cabinet must meet the eia standard eia 310 d for 19 inch racks.
Hole spacing is either on 1 inch 25 mm centers western electric standard or the same as for 19 inch 482 6 mm racks 0 625 in or 15 9 mm spacing.
The size denotes the width of the faceplate for the installed equipment.
This three hole group is defined as a rack unit ru or sometimes just call a u.
Horizontal spacing of rack units depend on whether or not the holes are drilled and tapped in the rack versus the use of cage nuts.
