Average Reliability

CenterPoint Energy maintains statistics of outage frequencies and durations for each distribution circuit and for the electric system as a whole. While there is some variation from year to year, the average figures customers may experience are as follows:

Duration of Sustained Outages = 3 hours per year
Number of Sustained Outages = 2 per year

Average Power Quality

We also maintain statistics of momentary outage frequencies for each distribution circuit and the whole system. While there is some year-to-year variation, the average figure that customers may experience is as follows:

Number of Momentary Outages = 10 per year

Besides momentary outages, instantaneous voltage sags are the most common utility-related power quality event that adversely affects our customers. While we don’t keep statistics on voltage sags, we did participate in a national power quality survey that accurately reflects what typical customers may experience:

Number of Sags Below 90% of Nominal Voltage = 70 per year

Of these 70 sags, 23 will dip below 70% of nominal voltage, which is generally considered the threshold for causing motors and other sensitive equipment to drop off-line.