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Understanding and Preparing for Outages

Outage Causes

Outages may last a few seconds or a few days, depending upon the cause. The most common causes of power outages are: natural causes, human error, and equipment failure. There are also occasions when maintenance will result in an outage.

Natural Causes

Strong storms can cause trees or branches to fall and tear down power lines; tree limbs brushing or resting on lines can cause short circuits and blown fuses. Lightning strikes can damage substations, power lines and equipment. High winds, heavy rain, salt, snow and ice also can damage equipment and cause outages.

There are several reasons why high temperatures can cause outages.

  • There is also the possibility of scattered outages resulting from equipment overheating. Transformers, for example, can fail from overheating. Transformers are built to dissipate their heat, but in extreme weather conditions such as we’re experiencing, there is no ability to cool because temperatures remain high throughout the night. Problems are also magnified in the confined spaces of an underground electrical system. For example, if there is a flaw or crack in the cable insulation, a short circuit could occur as the cables expand from the heat.
  • Increased demand for air conditioning means more electricity flowing through power lines. This causes them to heat up and expand or sag, and in some cases they sag into tree branches, causing a short circuit.
  • Electricity loads combined with high temperatures cause transformers to heat up, sometimes reaching critical levels that if uncorrected would permanently damage the equipment. The equipment will automatically and safely shut down to protect itself and other equipment.
  • High current causes stretching of cables, switches and other equipment and can increase the size of minor flaws in insulation or connections.
  • Electric equipment can be weakened by lightning strikes and circuit failures, making it more susceptible to an outage as it can no longer withstand the increased flow of electricity during periods of high demand.

Small animals, like squirrels, sometimes chew into lines or come into contact with a piece of equipment and an energized line, resulting in their untimely demise, and an interruption of electric service for you.

Human Error

Digging a foot or two in the wrong direction can damage underground power lines, causing an immediate outage or contributing to an outage that occurs days, weeks or months later. Hitting a power line can also result in serious injury.

Before digging anywhere, call Miss Utility at 811. Please allow at least two business days in advance whenever any excavating activities are to be performed. Failure to call before you dig may result in criminal or civil penalties.

Vehicle Accidents
Vehicle collisions with utility poles or equipment can also cause outages. These outages can be frustrating for residents who may live some distance away and are unaware of the cause.

Metallic balloons that are released into the air can drift into power lines or electrical equipment and cause power outages.

Equipment Failures
Just like with your car, in spite of regular service, mechanical systems do break down occasionally. The same is true of even the best-maintained electrical distribution and transmission system.

Momentary Outages

A power outage is inconvenient, whether it lasts a second or an hour. But there is a difference between a prolonged power outage and a brief, momentary interruption.

"Momentaries" are split-second interruptions in service. They are an unavoidable part of power delivery systems that have always occurred. Today's sophisticated computers and other electronic equipment are super-sensitive, however, and can be affected by a momentary that lasts only one eight-thousandth of a second.

While annoying, momentaries serve an important purpose. For example, when a tree limb falls on a wire, Delmarva Power's automatic sensing equipment detects a potentially dangerous condition and temporarily breaks the flow of electricity protecting essential parts of our delivery system from major damage. Nevertheless, power may be out just long enough that equipment in your home, like your VCR or microwave, needs reprogramming when you return home.

Preventing Outages

What is Delmarva Power doing to reduce the incidence of outages?

  • We prune trees along our power lines on a regular cycle to help prevent them from damaging or blowing into our power lines.
  • We use special insulated wire in heavily wooded areas that can better resist damage from falling tree limbs.
  • Lightning arresters are in place to provide a harmless path to the ground for electrical surges.
  • We use grounded shield wire above some power lines that acts as a shield from lightning strikes.
  • We install animal guards around our field equipment to protect against short circuits caused by animals.
  • We continually upgrade our facilities to keep pace with growth in our area and enhance reliability.

Preparing for Outages

Make a Plan and Assemble a Kit

Assemble an Emergency Storm Kit

Keep these items on hand:

  • Flashlights and fresh batteries
  • Battery-powered radio or television and extra batteries
  • Land line phone with cord (Cordless phones require electricity to operate)
  • Battery-powered or windup alarm clock
  • A supply of bottled water (one gallon per person per day)
  • Non-perishable foods that require no heating
  • Blankets, bedding, or sleeping bags and a change of clothes
  • First Aid Kit and prescription medications
  • Hand-operated can opener
  • Special items for infants, the elderly or family members with special needs
  • Hand tools such as a hammer, screwdriver; scissors; duct tape; plastic garbage bags; paper and pencil; waterproof matches; household bleach
  • Identification and copies of important family documents in a waterproof container
  • Emergency Services and Delmarva Power telephone numbers

Collect and store these items ahead of time in order to save valuable time and to be prepared in the event of a wide variety of potential emergencies. Check the links under Additional Resources to our Federal, State and local Emergency Management Agency partners for additional information on preparations for potential emergencies.

Protect Your Food

  • Stock up on shelf-stable foods such as canned goods, juices, peanut butter, "power" bars, trail mixes and "no-freeze" entrees.
  • Plan ahead how you can keep foods cold. Buy some freeze-pak inserts and keep them frozen. Buy a cooler. Freeze water in plastic jugs or containers or store bags of ice.
  • Know in advance where you can buy dry and block ice.
  • Develop emergency freezer-sharing plans with friends in another part of town or in a nearby area.
  • Keep freezer and refrigerator doors closed; open them only when absolutely necessary. Food will stay frozen for 36-48 hours in a fully loaded freezer if you keep the door closed.
  • A half-full freezer will generally keep food frozen for 24 hours. If you have time in advance of the storm, fill up your freezer by filling plastic bottles with water and freezing them.

Protect Electronic Equipment

  • Purchase electronic equipment with built-in protection or a battery-powered back-up system.
  • Use electrical surge suppressors or arresters on all sensitive electronic equipment. Most are designed to be plugged into a wall outlet.
  • Plug computers and other sensitive electronic equipment into a separate, grounded circuit to isolate them from fluctuations caused when a major appliance starts, such as a room air conditioner or refrigerator.
  • Consider a UPS (uninterruptible power supply) for temporary battery back-up power for sensitive electronic equipment.
  • Consider having a lightning arrester installed at your main circuit panel. This generally requires the services of a licensed electrician.

Stay Alert for Downed Lines

  • If you see a downed power line, let Delmarva Power know immediately by calling 1-800-898-8042 (New Castle County [DE] and Cecil and Harford Counties [MD]) or 1-800-898-8045 (Kent and Sussex Counties [DE] and the
    Eastern Shore of Maryland and Virginia). Stay away from any downed line. Assume it's live and dangerous, and warn children to stay away and notify an adult. Downed lines do not always spark, burn or arc. Never assume any downed wire is harmless. Objects such as metal fences and water in contact with power lines could be energized and lethal. STAY AWAY.

Protect Your Home and Belongings

  • Turn off all appliances, including your furnace, air conditioner, water heater and water pump. That way, you can avoid a circuit overload and another outage that may result when power is restored to all appliances at once.
  • Leave on one lamp so you'll know when the power is restored.