in a lightning protection system is the interconnection of all
metal bodies to the system. You don’t want a side flash from
a grounded metal body to an ungrounded body. Consequently,
metal bodies like air conditioning systems, exhaust fans, vent
pipes, railings, are bonded to the equipment and other metal
objects that are on the roof.
“With all the roof-top elements now connected and bonded,
we then ran copper down-conductors to grounding electrodes
placed at the required average 100-ft spacing around the
building. We also interconnected selected down-conductors
to the building’s phone, water, communications and electric
systems by way of wall penetrations. Now everything that
involves electricity or grounding is at the same ground potential“
(Figure 5).
Figure 6. Indoor grounding bus with wall penetration (left); the
right-hand photo shows one of several outdoor wall penetrations,
from which the heavy-gage copper conductor to the left of the
penetration lug leads downward to a driven earthing electrode.
“Tricky” Aesthetic Considerations
Figure 5. Rooftop lightning protection system on Mount Ararat’s
“new” building. Note Franklin rods mounted on all metal bodies
on the roof, whether grounded or not. All equipment is bonded to
a network of grounding conductors that, in turn, are bonded to a
conductor ring encircling the structure at the roof’s parapets. The
ring serves the same purpose as a conventional buried ring-ground
on properties where excavation is practical. From the rooftop ring,
copper down-conductors lead to driven 10-ft grounding electrodes.
Has the fix worked? So far, and despite the passage of several
severe thunderstorms, there has been no evidence of any
electrical surges in the buildings, and no equipment damage. Mr.
Lutsky, who works in the building every day, says it best: “I do
feel safer about the building since we’ve had the new protection
system installed. We’re not experiencing any more surges. We
went through a storm the other day and nothing happened! It
was great. At the end of the storm I felt secure.”
Connections to Indoor Systems
The ground conductors of interior electrical, communications
and safety systems, as well as water lines, were connected to
common grounds that terminate at copper grounding buses
located at convenient spots throughout the structures. The
buses were located near to down-conductors at the outside of
the building so that through-wall connections could be made
between the down-conductors and the grounding buses. (Figure
6). In this manner, all interior and systems were now common to
the rooftop ring and the driven earthing electrodes, placing the
entire complex at the same ground potential. It was this feature
of the lightning protection and grounding system that ended the
surges and electrical damage the complex had experienced for
years.
4
“The folks at Mount Ararat were sensitive to aesthetics,” recalled
Mr. Loehr, “and so are we!. When you’re working with new
construction, you can hide conductors in conduit or elsewhere,
but you don’t have that luxury with existing structures, like those
at Mount Ararat. You have to match the existing conditions.
Here, the older building and the towers on the newer structure
have dark brown shingle roofs, and copper blends in well with
that as the conductors oxidize, (Figure 4). They have brick walls,
particularly on the older structure, that also tend to hide the
copper. We also ran down-conductors next to downspouts to
make them less conspicuous, less obvious, (Figure 7), and we ran
cable along edges and corners. If you do it carefully, the cables
are almost invisible.
“When it comes to gutters and downspouts, we could have
just run the down-conductor over the gutter and down the
downspout or leader. That meets the standard, but it really
doesn’t look that great. What we do is run the cable through the
overhang or the gutter with a solid rod enclosed in a water-tight
fitting. It eliminates the awkward looping and it’s a lot less
conspicuous, (Figure 7).
Figure 7. Rather than looping
down-conductors over gutters,
Loehr Lightning Protection
Company routes them through
the overhang when necessary,
sealing the penetration with a
solid copper rod enclosed in a
water-tight fitting. The result
is a cleaner, less conspicuous
installation.
Mr. Loehr has strong
opinions regarding grounding
connections: “You might
want to use a mechanical
connection where you
have to construct a ground
path at a disconnect, and you don’t have the luxury to use an
exothermic weld. But generally, as part of a system like this, we
like to go with an exothermic weld. Also, our protection systems
utilize only Franklin rods, I’ve never been a believer in lightning