TFC WATCH ACFT HAS ELECTRICAL PROB. LOST COM.

Narrative

WHEN I WAS ON A TFC WATCH FLT CIRCLING ABOVE TOLL PLAZA BAY BRIDGE AT 2000 FT MSL; I LOST MY ELECTRICAL PWR. THE LAST THING I HEARD WAS THE ATC ANNOUNCING THAT HE LOST MY XPONDER. WHEN I TRIED TO RESPOND THE RADIO TOTALLY DIED. AT THIS POINT; I LOOKED AT THE AMMETER AND SAW THAT THE NEEDLE WAS JUST A LITTLE BIT OFF TO THE NEGATIVE SIDE. I TOUCHED THE LOW VOLTAGE AND IT ILLUMINATES. DURING THIS TIME I DECIDED TO LEAVE THE CLASS C AIRSPACE TO THE NE BECAUSE OF LOST RADIO COMS WITH THE ATC. WHILE LEAVING THE CLASS C AIRSPACE I STARTED TO TROUBLE-SHOOT. I TURNED OFF ALL ELECTRICAL EQUIP AND RECYCLED THE MASTER SWITCH. THE AMMETER SHOWED A STRONG POSITIVE LOAD AND THE LOW VOLTAGE LIGHT GOES OFF. TO BE ON THE SAFE SIDE I DECIDED TO FLY BACK TO HAYWARD ARPT AND LAND. I TURNED ON THE RADIOS JUST OUTSIDE THE CLASS D AIRSPACE AND PICKED UP THE ATIS AND TALKED WITH THE TWR AND LANDED. WHAT I MISSED ON MY RUNUP WAS TO RECYCLE THE ALTERNATOR SWITCH AND TO CHK THE AMMETER PROPERLY. SO BY FOLLOWING THE CHKLIST AND NOT LETTING ANY PRIVATE PROBS INTERFERE WITH THE FLYING; A PROB LIKE THIS SHOULD NOT OCCUR AGAIN.