Public Utilities Code § 15505

“Elector,” “voter,” or “qualified elector,” means a voter whose name appears on the great register of the county in which the district is located, or any supplement thereto, allowed by law to be used to determine the eligibility of persons to vote at municipal or county elections, and whose address as it appears on the great register or supplement is in the same unincorporated territory as the address given by him on the certificate or petition that is signed by him.