Transient magnetic fields and currents in residences

Attention has focused on transient magnetic fields and a possible association with power lines. An instrumentation system was developed to record the transient magnetic fields and currents in residential wiring across a wide bandwidth from approximately 10 Hz to 500 MHz. The system was used to measure the transient magnetic fields and currents over a 24 hour period in 21 residences. Multiple transient events were recorded in the residences. The magnetic field (B) and its time-rate-of-change (dB/dt) were analyzed to extract their key features such as maximum, peak-to-peak, mean and RMS amplitudes. Analyses of the transient field with respect to frequency content, wire coding and internal/external source were performed. Residences with a wire coding classification of very high current configuration had significantly more external transient effects than other residences.