Cooperative Living January 2018 - 29

YourBusiness | by Preston Knight, Contributing Writer
The Pros & Cons of
Underground Electric Lines
D
espite the fact that underground
electric lines tend to be more reliable
and are less likely to fail than the
overhead alternative, they generally have
much higher installation and maintenance
costs than overhead lines.
While it's not uncommon to install
underground lines as part of the
construction of a new subdivision or
shopping center, it's much more costly and
challenging to install underground lines in
areas with rocky terrain, or in rural areas
requiring miles of distribution system
infrastructure.
Another notable disadvantage is the
restoration of power to underground lines
versus overhead: You can't fix what you
can't see.
When power is lost from lines located
beneath the surface, the problem is most
likely buried about 3 feet underground
and will require a tedious process of
elimination to identify what needs repair.
Since visual identification is next to
impossible, detecting the source of
underground troubles is instead a matter
of fixing what you hear or feel first. Crews
use a " thumping " device to connect to
failed underground line sections that will
send signals over the line to pinpoint the
exact location of the problem.
Even as fault-indicator technology and
sectionalizing equipment improves to
decrease the time it takes to isolate a
problem, line crews still might have to
wait for Miss Utility, resulting in a threeor-more-hour
delay in digging. The
restoration could then require digging
down several feet to create space large
enough for a lineman to handle the
underground cable.
That's a pretty complicated solution
compared to the relatively simple eye test
used for overhead issues that can lead to
an almost immediate fix. It's easy to spot a
downed wire, a bad insulator or
transformer, or a tree on the line caused by
weather or human error of someone
cutting a limb onto the line.
It's important to understand that
underground lines aren't foolproof. They
are more vulnerable to soil corrosion, the
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A notable disadvantage is
the restoration of power to
underground lines versus overhead:
You can't fix what you can't see.
Shannon Detamore, an equipment operator with Shenandoah Valley Electric Cooperative,
operates a vibratory track plow as lineman Jared Armstrong feeds the cable they are
installing underground.
movement of moisture into the cable and
animals that may find their way in to
wreak havoc. Flooding can be a major
issue for buried wire, and lightning also
has an impact, as the U.S. Energy
Information Administration notes on
its website.
Finally, age is a factor in causing
outages. Underground lines don't last
as long as overhead wires, although
technological advancements have been
made over the years.
And because underground distribution
circuits are typically still linked to aboveground
facilities, such as substations and
transmission lines, homes and buildings
served by underground infrastructure will
not necessarily be spared in the event of
system-wide outages from a major storm.
The takeaway from this discussion?
Underground power lines provide a
tradeoff when outages occur. Ice and
wind aren't factors as they are for
overhead cable, but rectifying any
problem can be time consuming and
may require a considerable digging
expense for the cooperative. 
Preston Knight is a public relations representative
for Shenandoah Valley Electric Cooperative, a notfor-profit
member-owned electricity provider that
serves more than 90,000 homes, farms and
businesses in the northern Shenandoah Valley. For
more information, go to www.svec.coop.
January 2018 | Cooperative Living | 27
PRESTON KNIGHT PHOTO
http://www.svec.coop http://www.co-opliving.com
Cooperative Living January 2018

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