When it come to gear in the rack a single lug on most 1u/2u gear is ok
for grounding inside the cabinet.
On 02/26/2017 02:08 PM, Ken Hohhof wrote:
1/4-20 and 5/8 spacing works for me, I don’t think you can satisfy
everyone. I would even be OK with a single ground screw, but some
people will make a reasonable case that a 2-hole lug is better, and
you can still use a single hole lug if that’s all you have.
The ground bars in shelters and at towers are typically going to have
dual 3/8 screws and wires will be #2 or heavier, but that is overkill
for what you are doing.
*From:*Af [mailto:af-boun...@afmug.com] *On Behalf Of *David Milholen
*Sent:* Sunday, February 26, 2017 9:31 AM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] Ground Lugs
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
forre...@imach.com <mailto:forre...@imach.com> |
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