The story behind repairing Friday night's icy power outage
By IRENE NOLAN
having survived an unusually harsh winter of snow, ice, high winds, and
stretches of below-freezing temperatures with barely a flicker,
Hatteras and Ocracoke's power system finally met its match last Friday
night, March 6.
After another day of temperatures hovering right
at the freezing mark and icy drizzle falling all afternoon and into the
evening, the lights went out on the islands at 6:37 p.m., and stayed
out in some villages for almost 6 1/2 hours.
The rest of the
night was anything but the warm, cozy end of the week most of us were
expecting. Indoor temperatures starting falling like a rock, and
residents used whatever they could to keep warm -- wood stoves,
fireplaces, and lots of blankets.
While Cape Hatteras Electric
Cooperative members were trying to stay warm, all of the staff returned
to work -- all 25 of them, including not only linemen but also
receptionists, bookkeepers, and managers.
It was a nasty night,
and the cause of the outage was in a nasty place -- a marshy area along
the Pamlico Sound in north Buxton. Bucket trucks couldn't get to
the poles, further challenging the linemen, who were forced to hike to
climb icy poles to get to the problems. One resorted to donning a
wetsuit to get to a pole in a canal.
Power was finally restored
to the last of the villages, Frisco, at 1 a.m. on Saturday morning, but
the CHEC staff continued to deal with scattered outages until almost
As grateful as islanders are to the linemen who put
their lives on the line literally that night, there have been questions
about exactly what happened, why it took so long to fix, why the whole
island couldn't have been switched to generator power, and why
different villages got power back at different times.
So we asked CHEC to tell us the story. Here it is.
QUESTIONS AND ANSWERS FROM CHEC
Friday, March 6, at 6:37p.m., the Cape Hatteras Electric Cooperative
had a power outage affecting all of Hatteras and Ocracoke
islands. The outage was caused by galloping lines in
Buxton. We have received many questions from the membership about
Friday’s outage that we would like to take the time to answer.
What are “galloping lines?"
lines are a phenomenon mostly seen in the upper Midwest where flat
terrain and harsh winters leave power lines susceptible to ice
formation. Ice causes normally round power lines to take on the airfoil
shape of an airplane wing. This causes the wire to lift in the
wind leading to a violent up and down whipping motion. The result
is that the lines bump into each other, putting additional stress on
the wooden cross-arms holding the wires in place.
Why did it take so long for crews to discover the problem?
the lights went out, CHEC’s relay system notified crews that the
breaker at Oregon Inlet had opened and that the problem was in the
vicinity of that breaker. Crews immediately headed toward Pea
Island to locate the problem.
Crew leaders soon
discovered that there was no problem in the area of Pea Island and that
the relay system had delivered incorrect information on where the
problem was. The crews now had to systemically work their way
back down the island to locate the issue.
This is a new
relay system that the Cooperative installed in November 2014. CHEC
management is diligently working to correct the issues with the new
system’s programming to avoid such extended outages in the
future. Normally, it would have not taken crews so long to find
the issue. The new system had an equipment malfunction and
delivered false information.
Why did some villages have power restored before others?
10:05, crews had cleared the system south through Avon and transmission
power was restored to Rodanthe, Waves, Salvo and Avon. The issue had
been isolated to the area of Buxton. It was around this time that the
galloping lines were discovered on the 115kV transmission line that
runs behind the Fessenden Center in north Buxton.
point, CHEC managers knew that it would not be a quick fix and that it
might take several hours to repair. The villages of Buxton,
Frisco, Hatteras and Ocracoke had been in the dark for nearly four
hours with outside temperatures hovering around freezing.
decision was made to turn on the diesel generator plant in Buxton to
provide temporary power to some members. The plant was unable to
provide power to all of the southern villages for two reasons:
had not been completed on equipment in the generator plant damaged by a
small fire last month, so all five of the engines in the plant could
not be used.
- There was a larger than normal load
on the system because of the very cold weather and the number of homes
being heated. Since temperatures in houses had dropped since the outage
began, the load would have been increased even more by all the
furnaces and heat pumps trying to warm these homes up at the same time.
know that Buxton has the largest year-round population, and they
decided that there were probably more year-round residents in Hatteras
village than Frisco. So Hatteras was chosen to receive the
Shortly after the generator was turned on, the
transformer in the Hatteras substation tripped offline because the load
was too large. CHEC issued a conservation notice to Hatteras
village and eventually got them back on.
Membership Corporation, which serves Ocracoke Island, also made the
decision to run the generator on Ocracoke, rotating the power
throughout the village.
Why didn’t CHEC start the generator sooner?
generator cannot be started until the entire system has been cleared
and the reason for the outage discovered. Putting electricity
back onto the grid before the problem is isolated is a safety hazard.
CHEC used all of its manpower to find the problem on
Friday night. It also takes a certain amount of
manpower to serve the circuits when the generator is running. In
addition, the load on the generator was too great to carry more than
How did CHEC linemen correct the galloping lines?
linemen had a daunting task on Friday night. After spending hours
in freezing rain and wind, their next challenge was accessing the
poles, as they are located in thick marsh. Because the bucket
trucks could not drive to the poles, CHEC linemen had to manually climb
the icy poles to stop the lines from galloping. This was an
especially difficult task to complete in the icy winter weather.
One lineman, Josh Austin, had to change to a wetsuit to get access to a pole located in a canal.
12:23 a.m. on Saturday morning, crews had successfully made their
repairs and were able to start picking up the rest of the circuits on
transmission power, starting with Buxton. Hatteras and Frisco
circuits followed, and the island was back on transmission power by
1:01 a.m. with the exception of scattered outages. Crews quickly
regrouped and returned to the field to finish restoring these scattered
outages, mostly caused by high load as a result of the extended outage
and cold weather.
CHEC is proud to report that the repairs were made without any injury or accident.
are grateful for our linemen who put their lives on the lines to
restore power to Hatteras and Ocracoke islands, using all of their
training and knowledge to complete this laborious task," said CHEC
general manager Susan Flythe. "We are also thankful for our loyal and
supportive membership, and the patience that they showed us on Friday