Forrest,
Use the motorola R56 standards for a base for all your grounding.
There are a few layered standards for grounding but motorola is on top
of these other standards for telcom gear.
I have always tried to be a good steward of these standards when using
existing sites but the Broadcaster towers built pre 1990
are a big challenge.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwj589iAiq7SAhWK5oMKHeHwCwUQFgggMAE&url=https%3A%2F%2Fsites.auburn.edu%2Fadmin%2Ffacilities%2Fspw-bid-calendar%2F11-150%2520AU%2520Regional%2520Airport-Construct%2520a%2520Self-Supporting%2520Radio%2520Tower%2FProject%2520Documents%2F1%2FMotorola_R56_2005_manual.pdf&usg=AFQjCNHlYoTBfjY-zLOUUebdvd3RLH_Cwg&sig2=gZT9-oejY-fxgK2TrdRnWQ
There are 518 pages of stuff but do a search for Rack and Rack equipment
grounding and you should find what you need.
Dave
On 2/25/2017 10:12 PM, Forrest Christian (List Account) wrote:
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] <mailto:[email protected]> |
http://www.packetflux.com <http://www.packetflux.com/>
<http://www.linkedin.com/in/fwchristian>
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--
