Opponents of Central Maine Power’s “smart meters” have formally filed a request with state regulators to delay implementation of the program.A complaint filed with the Maine Public Utilities Commission seeks to stop installation of the devices and allow C.M.P. customers to opt out of the program.C.M.P. recently began a two-year project to replace 620,000 electric meters with new digital ones that transmit data through a series of antennas. C.M.P. says smart meters will help customers reduce energy use, help the environment and allow utilities to quickly pinpoint problems during power outages.Critics contend the wireless signals are linked to health problems.Maine’s health director likened the risk to that of cordless telephones and wireless internet routers.