Don't Be Left in the Dark About Power Outages
Consumer Brochures

Causes, Prevention & Restoration


Power outages are inconvenient for customers and costly to the utility. Electric customers must make do without lights, cooling and heating until service is restored. Restoration efforts can be very costly to the utility and can sometimes take several days to complete if the damage is widespread.

There are many causes for power interruptions - some preventable and some not. The most common causes are:

  • Lightning
  • Automobile accidents
  • Wildlife
  • Excavation
  • Storms
  • High winds
  • Snow or ice
  • Vandalism
  • Equipment failure
  • Overgrown trees

Abnormal conditions (such as lightning) can cause an open circuit, a ground, or a short circuit. These are called "faults." An open circuit occurs when one or more conductors are broken and the broken ends separate. A conductor which contacts the earth causes a ground; the electricity flows out of the circuit into the earth. A short circuit occurs when a connection is accidentally established between two conductors, causing an overload on one or more conductors.


Outages should be reported directly to the utility. However, you should first check with neighbors to determine if the outage has already been reported before making your call. By reducing duplication of reports, the utility's telephone lines can be kept open to receive emergency reports of downed power lines and outage reports from other areas.

Utility customers often call the PSC to request help in expediting restoration of their electric service during a power outage. Unfortunately, the PSC does not direct the utilities' field crews and cannot expedite restoration. However, customers reporting extreme medical emergencies (such as life support equipment on premisis) are reported to the utility. Customers with medical concerns should submit medical certification to the utility so that the account can be noted that a medical condition exists.

If someone in your home has a medical condition that could be aggravated by a power outage, you should develop a plan for relocating the patient during an outage or have battery or generator backup available.



Code of Maryland Regulations requires utilities to provide safe, reliable, and adequate service. The regulation specifically requires that "the electric plant of the utility shall be constructed, installed, maintained and operated in accordance with accepted good engineering practice in the electric industry to assure, as far as reasonably possible, continuity of service, uniformity in the quality of service furnished, and the safety of persons and property."

It is impossible to prevent outages entirely. However, utilities use preventive measures, such as those listed below, to improve reliability of service:

  • Lightning arrestors
  • Grounded shield wire
  • Tree-trimming
  • Tree wire and fully insulated aerial cable or
    partially insulated cable in heavily treed areas.
  • Wildlife protection (squirrel guards)
  • Regular inspections using ground and aerial patrols



In addition to the preventive measures listed above, an additional system of protective devices helps to limit outages to localized areas.

Circuit breakers are switches located in substations which automatically interrupt the flow of electricity during overloads or short circuits. Fuses perform the same function on distribution lines.

A recloser, which is another type of switch located on main lines, opens the circuit in case of a fault as would a fuse or circuit breaker. However, reclosers open the circuit temporarily and then reclose it several times, thus maintaining the circuit in the event of a temporary fault. (A tree limb brushing against a conductor is an example of a temporary fault). Although the momentary outages that result can be annoying, causing the need for resetting digital clocks, etc., reclosers are effective in reducing outages of longer duration.

Other devices, called sectionalizers, are used to isolate the location of permanent faults on distribution circuits, keeping the number of customers out of service to a minimum. These devices are usually installed on lines off the main circuit.



While there are no Public Service Commission guidelines or regulations specifically concerning a utility's tree trimming practices, tree trimming is one of the accepted methods used by a utility to maintain its equipment. In past years, tree trimming was primarily done only when utilities received reports of trees causing outages or safety hazards. However, in the last few years, most utilities have begun "Vegetation Maintenance Programs," which involve trimming back growth near the utility's lines according to a regular maintenance schedule. Tree trimming is also performed as needed to correct existing tree interference or safety hazards.


Whether or not you experience frequent power outages, you should be prepared in the event an outage occurs. The following items can help you prepare for a loss of power:

  • Flashlights and/or battery-powered lanterns with fresh batteries
  • Candles and matches (use with extreme caution)
  • Bottled water
  • Non-perishable food (such as canned food) and a manual can opener
  • Battery-operated radio with fresh batteries
  • First aid kit
  • Propane grill, charcoal grill or camp stove


Most homes and businesses have an array of electronic equipment that is sensitive to power surges. Solid State technologies using microchips have made home and office equipment sensitive to electrical spikes, surges and fluctuations in voltage. Such interference can both damage and affect the performance of valuable equipment such as TVs, VCRs, computers and major appliances.

Electric utilities install special equipment (lightning arrestors and wild life protections) to minimize the number of occurrences to its primary equipment. While these are efficient, some fluctuations in voltage are simply unavoidable. The utility is NOT required to replace or repair equipment damaged as a result of a fluctuation in voltage, such as a surge. Therefore, you should consider high quality surge protectors to reduce the risk of surge damage. Some utilities provide surge protection for an additional cost. (This service is not regulated by the PSC). In addition, surge protection equipment is available at most retail stores or through an electrical contractor. If surge protection is not available or not affordable, sensitive equipment should be unplugged during electrical storms or outages to avoid possible surge damage when power returns.


Generally, utility companies are not liable for damages due to power outages/surges unless damage resulted from willful neglect by the utility. However, allegations of willful neglect can only be decided by a court of law. The PSC cannot adjudicate damage claims. You should consult with your insurance agent to find out if your homeowner's or renter's policy covers losses due to power outages.


No utility can guarantee uninterrupted service. Code of Maryland Regulations provides that "[e]ach utility shall make reasonable efforts to avoid interruptions of service, but when interruptions occur, service shall be re-established within the shortest time practicable, consistent with safety."

The PSC monitors the restoration efforts of the utility during widespread power outages. The utilities continually update the PSC regarding estimated time to restore service to all customers (not to localized areas).



When the PSC receives complaints about frequent power outages in a community, we request a thorough investigation by the utility. The utility provides the PSC with the dates, duration, and cause (if known) of the outages, and any efforts already undertaken by the utility to improve reliability, as well as any improvements planned for the future. If necessary, the PSC's Engineering Division is consulted to determine whether the utility's efforts are adequate and appropriate to improve service reliability. Remember, the utility does not guarantee uninterrupted service and the PSC cannot assist you in obtaining compensation for losses resulting from a power outage. The PSC's role in examining complaints of frequent outages is focused on quick restoration and prevention of future outages.


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