Extreme Heat and Humidity Drive Heavy Demand

Washington, D.C. - Pepco reminds customers that, even though adequate supplies of power are available, during the extreme heat and high humidity - forecast for the next few days, - it is especially smart to conserve energy to help ensure the reliability of the electric delivery system.

As customers try to keep cool with air conditioning, increased demand for electricity affects distribution lines.  Increased power flowing through the lines causes them to heat up and expand or sag.  In some cases the sag is great enough that the line comes into contact with tree branches growing near the line, causing a short circuit or outage. The high current flow can cause heating and stretching of cables, switches and other equipment allowing minor flaws in insulation or connections to grow, resulting in an outage.

Electricity loads in combination with high ambient temperatures can also cause transformers to heat up to very high temperatures.  Such conditions can permanently damage equipment.

Pepco offers these tips:

• Set your air conditioner thermostat as high as health permits.
• Close curtains and blinds to keep out the sun's hot rays and retain cooler air inside.
• Postpone using major electric appliances such as stoves, dishwashers and clothes dryers until the cooler evening hours.
• Turn off non-essential electric appliances and equipment that can heat up your home or business.

With the high temperatures predicted for this week, there is the potential for record-setting electric usage by Pepco customers. Peak demand for Pepco was set July 27, 2005 when usage hit 6,725 megawatts.

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Pepco, a subsidiary of Pepco Holdings, Inc. (NYSE: POM), delivers safe, reliable and affordable electric service to more than 745,000 customers in Maryland and the District of Columbia.