French Broad Electric Membership Corporation

General Manager's Report Jeff Loven

Why Do The Lights Blink?
April, 2010

Do you ever wonder why your lights blink off and come right back on? Sometimes they only dim for a short period of time, then return to normal. What is happening? Why can the power not be on all of the time? With the recent snow and ice storms within our service territory, many of us know the realities of the power system service reliability. There are many reasons that the power can be interrupted. Primarily this is due to faults on the overhead power lines, which we all see along the roads in our neighborhoods.

When trees fall on the power lines, they either lay on the lines causing them to contact each other or the lines and poles break, falling to the ground. In either case, the normal line current is elevated due to contact with the ground or another power line. Keep in mind that “current” is the amount of electricity that flows through the power line and is used to power the electrical devices inside our homes. If lines come into contact with one another or with the ground, the resistance is lowered, thus the current increases dramatically.

Protection devices, such as breakers and fuses, are installed throughout the electrical network in an effort to keep the entire power system from overloading due to the high fault current level. The main objective of a breaker and a fuse is to isolate the particular area that is experiencing the fault and to allow the rest of the system to remain energized.

A fuse will operate, or “blow”, if the current reaches a certain level and the line will remain de-energized until one of our line technicians repairs the power line and replaces the fuse. A breaker will also sense the increase in current and “open up”, similar to a fuse. However, a breaker will automatically close back; allowing a temporary fault time to clear itself from the power line. It will go through this sequence up to four times in an effort to make certain the fault is not temporary. Upon the fourth operation, the breaker will remain open until a technician repairs the line and closes the breaker manually. Breakers greatly reduce outage time by allowing temporary faults, such as lighting strikes, tree limbs or small animals, time to clear themselves from the line and then restore the power automatically. The blinks you see are the result of these breaker operations and the breaker doing its job properly. While these blinks can be a nuisance to some, keep in mind that it is far better to have the lights blink than to be without power for extended periods of time.

Our electrical protection scheme is designed to keep the power system stable by isolating only the components that are under fault, while leaving as much of the network in operation as possible. Reliability of service is a major goal for French Broad Electric and power system protection equipment is vital to ensuring that service is as reliable as possible, given the exposed nature of our electrical grid.

Thank You,

Jeff Loven
Email: jeff.loven@frenchbroademc.com

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