So, I've now had two people ask me to include a ground strap point on the
back of the new rack injectors. So I figured, I'd just go figure out what
the standard was for the hole spacing, screw diameter, and similar, and add
it to the list of things which will be modified slightly in a future batch
of enclosures - shouldn't be much more expensive to get them to mask off a
small section when painting and add the appropriate screw bosses....
Simple, right?
Well, that was until I tried to find the standard.....
In a juniper manual I discovered they have two sets of bosses.... one with
1/4-20 screws, one with M6 Screws... the 1/4-20 screws are for the US
market and the M6 ones are for the European market. Ok, I get that...
Metric vs US. But then the spacing is 0.625 (5/8) inches for *both* of
them - not say for instance 0.625in and 15 or 16mm which would make sense.
So I figured I'd look around more...
Then I go over to the cisco manual. They use M4x8 screws on most stuff,
sometimes something different. Spacing seems to be around 1" (freakin
metric screw and english spacing).
After 2-3 more vendors of total inconsistency, a word comes to mind:
Cobblefuckery. Pure Cobblefuckery. WTF? I thought this was for
grounding in a Telco environment, and shouldn't this be specified out the
wazoo by telcordia, with all of the vendors falling over backwards to make
their equipment NEBS compliant with exactly the right hole spacing for
grounding? Maybe two competing standards for English vs Metric, but not as
it seemed, everyone making up their own crap. Although the 5/8" spacing
and 1/4" or M6 screws seemed to be slightly more common than all of the
other pure randomness I was finding.
So the NEBS thought lead me down the rathole of telecom standards.
Eventually I find ANSI/TIA-607-B - it looks like the 5/8" spacing and the
1" spacing are both specified in ANSI/TIA-607-B for grounding busbars. The
hole diameter for the 5/8 spacing holes is specified as 5/16" on the
busbars, which seems to be a good match for a 1/4-20 screw. So it seems
like the juniper spec of 1/4-20 on 5/16 spacing would match a lug designed
for a ANSI/TIA-607-B compliant busbar. The M6 would be fine too - just a
bit smaller... The spec also lists 8mm holes on 16mm spacing as a option
for the exact same holes which I guess would be close enough since we're
really only talking about a millimeter or so here - probably a bit more or
less slop, but still close enough to work.
But what about that cisco spec of 1" spacing with a M4 screw? I'm still
not sure WTF they were thinking. ANSI/TIA-607 specs a 11mm diameter hole
at 1" spacing. A M4 screw isn't going to work well in a 11mm hole.
Cisco... go figure.
At this point, my intent is to see about including two 1/4"-20 screw holes
spaced at 7/16" and appropriate bare metal in a future revision of the
rackinjectors. Does anyone have any reason why this isn't the right
spacing and hole diameters? Or maybe even some validation that I got this
right?
--
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
[email protected] | http://www.packetflux.com
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