chapel some years ago. The chapel wasn’t damaged this time, and
Loehr’s nameplate was on the wall, so I gave them a call.
The person Mr. Lutsky contacted was J. J.Loehr, president of Loehr
Lightning Protection Company, a nearly 70-year-old, Richmond,
Virginia-based family business. Mr. Loehr is also a master
installer/designer as certified by the Lightning Protection Institute
(LPI).
The first thing that struck Mr. Loehr was that although portions of
both structures were grounded to earth, the buildings’ electrical
and grounding systems weren’t connected to each other. Mr.
Loehr concluded that this situation stemmed from the church’s
incremental growth history.
In fact, the churches grounding systems were a hodge-podge
waiting for trouble. “For example” Mr. Loehr recalled, “the older
portion of the church, which has a gable roof, had steeple
protection only, and even that was questionable. The new
building and its flat roof had some lightning protection but only
in scattered locations. There was some grounding to earth here
and there, but none of those systems were interconnected, so
a lot of the surge and stray-current problems the church had
been experiencing over the years were likely due to differences in
potential between the various grounding systems and between
the two buildings themselves.
Ground Resistance Not a Problem
“We’re lucky here in central Virginia because we have good,
moist, conductive clay-bearing soil. We’ll typically get ground
resistance readings lower than two ohms for systems like Mount
Ararat’s. We don’t have to drive deep electrodes or augment the
electrodes chemically.
Down-conductors extend from the roof’s perimeter ring to
grade, then they turn away from the building underground
approximately two feet to clear the foundation. At those points,
they’re exothermically welded to ¾-in X 10-ft copper-clad
ground rods. The 10-ft ground rods are standard in the industry.
NFPA 780, the standard for installation of lightning protection
systems, specifies that the tip of the rod must be 10 ft below
grade. You can dig a 2-ft hole and use an 8-footer, but we just go
with a 10-ft electrode.”
There are two low architectural towers on Mount Ararat’s newer
building, (Figure 4). The architect had specified an air terminal
atop each of the two towers, and that down-conductors should
connect the terminals with building steel. That’s just what was
done. But there was no mention in the construction spec about
grounding the building steel. As a result, the towers and their
inviting air terminals weren’t really grounded at all.
“What we did to correct this situation was to install a new
rooftop lightning protection system on the new building and
use that system as a facility-encompassing bus to tie all of the
various grounding and electrical systems together, exactly like
one would do with a conventional buried ring-ground except that
it was at roof level. That made sense in any event, first, because
we had to connect all the air terminals on the roof anyway, and,
second, because placing the ring on the roof avoided having
to install a buried ring-ground through parking lots, roads and
sidewalks, not to mention the cemetery, (Figure 3). We installed
additional driven electrodes per UL Standard 96A, then bonded
them and all existing ground electrodes to the roof-top ring.
Figure 4. The weathered copper down-conductor leading from the
Franklin terminal on one of the church’s two towers blends well
against the roof’s reddish shingles. Attention to aesthetic details
such as this helps make externally mounted lightning protection
system components unobtrusive elements of the building’s
appearance.
Mr. Loehr’s fix was to bond the two tower-mounted air terminals
to the rooftop lightning protection system and, by way of a
heavy-gage, buried copper conductor, connect the grounding
systems of the old and new structures. Doing that ensured that
the facility’s entire grounding and electrical systems were finally
at one common potential.
Figure 3. A small cemetery remains adjacent to the Mount. Ararat
Baptist Church. Along with roadways and paved parking lots, the
cemetery made the installation of a conventional buried ground ring
impractical.
www.copper.org
“Technically, we installed a perimeter Class I system on the
new structure — that’s for installations less than 75 feet above
ground. A perimeter ring runs along the parapets. The ring
is bonded to the air terminals, the HVAC system equipment
and all other metallic bodies on the roof. What is important
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