EFD System For Power Poles Hard Case Sensors Early Fault Detection RF Signal 284V. The EFD system is a preventative maintenance technology that remotely detects and locates radio frequency (RF) signals emitted by incipient energy asset faults, i.e. situations likely to develop into permanent faults or wildfire if left unremedied. EFD works independently of the mains-frequency operation of the power system and finds emerging low-current faults just as well as it finds high-current ones. The EFD data collection site is designed for fast deployment and quick installation. The site can be powered by a secondary main supply or solar battery power supply. No outage is required during installation.