Edison officials say they have 52 sirens in strategic locations.
In Orange County the sirens are located in San Clemente, Dana Point and San Juan Capistrano. In San Diego County the sirens are located in San Onofre and Camp Pendleton.
The testing began at 10 a.m. and continued until noon. The sirens emit a continuous steady tone to distinguish them from fire and police sirens.
During the test period sirens were activated several times for about three minutes each time.
City News Service contributed to this report.