Attention has focused on transient magnetic fields and a possible association with power lines. In order to study transient magnetic and electric fields, an instrumentation system has been developed that can record the magnetic field, the electric field, and the currents in residential wiring across a wide bandwidth from approximately 10 Hz to 500 MHz. The outputs from all sensors are displayed and recorded on a digital oscilloscope that has a sampling rate of 1 gigasample/second. Multiple transient events are recorded by interfacing the digital oscilloscope to a personal computer. Eight channels of information can be recorded simultaneously. The data acquisition system is versatile and can be used to record other high speed transient events using appropriate sensors. Measurements of high frequency electric and magnetic fields were made with the system. The instrumentation, the system configuration, and the system performance are described.