Where fields come from
Electric current produces a magnetic field. That makes power lines, household wiring, and operating electrical appliances possible sources. An electric field is different: it is associated with voltage. Measuring one does not tell you the strength of the other. NIEHS explains the distinction.
In the United States, mains electricity normally alternates at 60 hertz: 60 cycles each second. Many other countries use 50 hertz. These power-frequency fields are different from the radiofrequency signals used by Wi-Fi and mobile phones, and from Earth's largely static magnetic field. See the NCI overview of field types.
Power lines and your home
Magnetic fields generally decrease with distance, but the current and arrangement of conductors also matter. Nearby sources inside the home can contribute alongside outdoor lines. A photograph of a utility pole—or a distance on a map—cannot establish the field at your bed.
Ordinary building materials do not readily block power-frequency magnetic fields in the way they can screen electric fields. Moving a cable underground does not eliminate its magnetic field. These distinctions are explained in the UK government's electricity-network guidance, section 2.9.
A field is not a stream of particles. At household power frequencies, the electric and magnetic fields are largely independent near the source. Moving lines in an illustration are visual cues, not objects traveling through a room. UKHSA explains low-frequency fields.
A practical next step
If you want to understand a particular room, begin with a suitable measurement at the places people actually use. Record when and where you measured, rather than labeling an entire home from one reading.
Our measurement guide explains how to make that record useful. For health questions, read the research overview: identifying a field does not, by itself, establish a health risk.
Educational information, not medical advice. EMF Oasis™ is developing a product in this field. Read our approach to evidence.