Measure first. Put numbers in context.

Choose the right measurement

For household power-frequency magnetic fields, use an instrument specified for AC magnetic fields at 50/60 Hz. A radiofrequency meter measures a different part of the spectrum. Check the manual for frequency range, units, sensitivity, and operating instructions. ARPANSA's measurement guide explains this distinction.

Look for documentation of the sensor axes, calibration, and reported quantity. Three-axis instruments can account for fields in three directions; a single-axis reading depends on orientation. RMS (root-mean-square) and peak are different ways of describing an alternating field, so compare like with like. The NIOSH measurement manual describes formal exposure-measurement methods; this short guide is not a substitute for a professional survey.

Make a useful record

1. Choose representative places. Include where you sit or sleep, not only the closest point to an appliance.
2. Record the conditions. Note the location, height, time, meter settings, and which nearby appliances are operating.
3. Repeat at different times. Electricity use changes. A short peak is not the same as an average over hours or days.
4. Keep comparisons consistent. Use the same instrument, positions, settings, and comparable operating conditions before and after any change.

ARPANSA recommends repeated readings and explains why an instantaneous reading cannot represent prolonged exposure. Formal assessments may require time-logging and a defined sampling plan.

Understand the limits

A single number cannot tell you whether a symptom was caused by a field or whether a product will improve health. A research exposure category is not an individual diagnosis. See our evidence overview before interpreting a reading in health terms.

Do not open electrical panels, alter grounding, disconnect protective conductors, or approach power equipment to investigate a reading. Ask a qualified electrician about possible wiring faults; discuss personal health concerns with a qualified clinician.