We call those guys RADIO COWBOYS :)
Usually independent or work for a utility and have OJT no class time or
shadow with a PRO that knows the dos and donts of cabling
of a new site.
RO provides a great course on Transient Overvoltage and Lightning
Protection. They go over anything at a telco or other mech sites you can
imagine. They cover alot of standards referenced by NFPA and NEC
Its a 2 day drill ur brain with great stuff and walk away feeling winded :)
On 04/10/2015 01:17 PM, ch...@wbmfg.com wrote:
Well, no matter what you do with isolation and fancy grounding
systems, everyone needs to understand single point grounding and do
it. One would think public safety radio techs would have at least
heard of R56 at some point in their career. I realize that is a very
old document, but it is still very relevant for 2 way sites.
*From:* George Skorup (Cyber Broadcasting) <mailto:geo...@cbcast.com>
*Sent:* Friday, April 10, 2015 12:09 PM
*To:* af@afmug.com <mailto:af@afmug.com>
*Subject:* Re: [AFMUG] APC PRM-24
Experience tells me that it definitely helps. Everything was perfectly
fine at a site for over a year until our local PD/FD/EMS joined us on
an FM site, then we started blowing fuses and surge suppressors left
and right nearly every storm. They added a busbar and screwed up the
single-point principle. Things calmed down after we fixed that. It's
never going to be 100%, but it's better than shit blowing up all the time.
On 4/9/2015 11:36 PM, Kurt Fankhauser wrote:
If you bond everything will you still loose electronics just won't
blow them up and make a huge mess or will it save everything?
Kurt Fankhauser
Wavelinc Communications
P.O. Box 126
Bucyrus, OH 44820
http://www.wavelinc.com <http://www.wavelinc.com/>
tel. 419-562-6405
fax. 419-617-0110
On Thu, Apr 9, 2015 at 11:33 PM, George Skorup (Cyber Broadcasting)
<geo...@cbcast.com <mailto:geo...@cbcast.com>> wrote:
Follow the single-point bonding principle and you'll will be fine.
On 4/9/2015 9:38 PM, Robert Haas wrote:
I hope, I just can't tell if I am being overly cautious or not.
On 2015-04-09 21:07, Lewis Bergman wrote:
Obviously, if you have been through RUS you have been through
the ringer and you have your ducks in a row. Sounds like
isolation would eliminate a possible source given your setup
and seem prudent.
On Apr 9, 2015 8:33 PM, "Robert Haas"
<rob-li...@bpsnetworks.com <mailto:rob-li...@bpsnetworks.com>>
wrote:
All the superstructure within the buildings are isolated &
bonded. A lineup of racks may be bonded together and then
bonded back to the I/MGB, the racks themselves are isolated
from the floor, walls and the cable rack. Same for cable
rack - it is all bonded together and then bonded to the
I/MGB but isolated from the walls, celling and racks etc.
We've gone through RUS inspections in the past and have not
failed any of our grounding/bonding portions.
Since the chassis is obviously metal there is a risk that
the surge could energize the rack, which given our past
experiences gives me the heebie-jeebies.
By isolating the chassis from the rack the only path would
be to the EGB and avoid the rack (and potentially other
equipment) absorbing the surge. At least that is my
thinking anyway. I guess that is where my question lies -
am I worried about nothing?
On 2015-04-09 19:14, Lewis Bergman wrote:
If you look at the relevant docs on the subject like
the Telco standard or R56 you'll see the rack itself is
part of the ground bus. This really is forced by
equipment designers. I can't think of many pieces of
equipment that chassis ground isn't equivalent to
ground reference in the circuit. You should ground the
rack as if it is an integral part of the IGB.
On Apr 9, 2015 4:56 PM, "Robert Haas"
<rob-li...@bpsnetworks.com
<mailto:rob-li...@bpsnetworks.com>> wrote:
We’ve been deploying the WB suppressors using the
prm24 chassis for over a year now and have ~30 or
so in the field.
I’ve had an uneasy feeling since day one about
mounting the PRM’s in the rack with other equipment
– to the extent of when I have the option I buy a
1u wall mount bracket and mount the chassis on the
wall next to the cable entrance (bonding to the
EGB). I’ve even isolated the chassis off the rack
using poly washers and poly screws (again bonding
to the EGB or MGB in a cabinet).
My line of thinking is that I do not want to risk
shedding the surge into the rack and potentially
into another piece of equipment. I do not trust
that the surge will follow the bond/ground wire to
the EGB or MGB and not go into the
rack/superstructure.
We’ve had this happen in the past where a redline
AN50-E was struck and the surge was brought inside
into the superstructure and took out $20k+ of cards
in one of our DMS10s. In that case there was a
polyphaser IF SS at the cable entrance that was
bonded to the ring – the polyphaser popped but not
before damage was done. The case of the IDU showed
arc marks around the ovals where the screws to the
rack pass through, the screws in the rack welded
themselves along with the bond screw in the chassis
(it was bonded to the EGB using the screw in the
back of the chassis).
Anyone else have the same feeling that bringing the
surge into the rack is bad juju or is
thatoneguysteve sitting there looking at me shaking
his head saying that guy is f*ing nuts?
