On 4/16/15 7:49 AM, Paul McCall wrote:
Mark,
Proposing to bond electrical ground with tower ground at the tower is
the opposite of what they are saying to do. I know, I know … we have
done that pretty regularly in the past. We had a coupe towers that
got total equipment losses a several different times… sometimes
multiple times in one lightning season. All the potentials were
within a couple ohms of each other … everywhere. We double, triple
checked everything. Still got pounded.
You can leave the electrical ground separate at the tower site if it
works for you. I'm pretty convinced that a lot of the damage we see to
electronics at the base is coming in on the power lines and grounding
out through the tower (and our equipment) when the tower ground is
significantly better than the electrical ground.
At the expert’s sugg4estion of not bonding everything together at
those 2 towers, we separated the grounds, and guess what… no more
damages (almost 2 years now) And I understand the concept, but the
grey area for me is… What about shielded Ethernet cables going up the
tower… I mean your APs are grounded (450s, ePMPs, sectors to the
tower, yet they would plug into your electronics at the bottom of the
tower…seemingly linking the two systems together regardless of intent.
I usually do shielded cable with the shield open (not connected to
anything) at the top and grounded to the tower ground at the base. It
seems to work pretty well for us.
I have lots of thoughts on that.. from shield kits on each Cat5 wire
…to isolating antennas with rubber from the tower…. Which we have
tried too, LOL.
I have had isolated antennas pick up huge static charges and blow out
equipment - but only on one specific tower. It was weird. Grounded that
setup to the tower and the problem went away - but we have plenty of
other LMG Cyclone equipment where the case is ungrounded due to the
plastic blocks that are part of the mount that have no issues.
It all starts to get a bit cloudy in understanding… over the years we
have had both paid and unpaid “experts” say…absolutely THIS is the way
to do it, yet the next guy contradicts the former guy more frequently
than makes me feel comfortable.
Yup. I tried researching all of this and bought a bunch of books on
lightning, grounding, etc.. They all seem to agree on grounding
everything together at a single point, yet as we have all found what
works at one site doesn't seem to work at the next site.
Mark
Forrest, I hadn’t thought about backing the breaker size down to 15A….
that makes sense. I will definitely try that & the bigger ground
cable to see if that helps at this site.
