Re: E
EMF (electromagnetic fields) is being used as a quick designation for effects of power frequency magnetic fields which were not supposed to be there as the wiring system was designed. This is usually dealt with as a "power quality" issue, but since it is a relatively new issue and only refers to power line frequencies,(not RF)it has it's own three letters. For better or worse.
The effect of the undesigned magnetic fields is to induce currents which interfere with sensitive electronic instruments and also to affect living organisms.
Most of these elevated fields are due to wiring errors (Code violations) and so introduce the additional hazards of overheating and possible shock.
The errors involve incorrect connections of neutrals which allow neutral current to leave its dedicated circuit and flow on grounding paths as well as on neutrals supplying other circuits. The result is called "net current", whose magnetic field is directly related to the amount of diverted neutral current.
The required grounding to metal water pipes also produces diversion of neutral from the service entrance conductor to water pipes, which returns to the transformer by way of other service neutrals, thus producing more net current paths. Now we tie into the "stray current" topic.
Karl Riley