EMF in Buildings

Magnetized structural steel in buildings can cause a number of interference problems.

Although rare, some buildings may experience EMI problems from structural steel which has become permanently magnetized during welding or by some other means. Elevated DC magnetic fields from the magnetized steel can cause interference with nearby computer monitors and/or TV sets.

Perhaps most prevalent, are either EMI equipment interference issues or concerns about possible health effects, from AC magnetic fields emitted by a building's electrical distribution system. Virtually all buildings have electrical distribution systems including breaker panels, transformers, cabling, etc. This equipment naturally emits magnetic fields and it is common to find multiple areas in buildings which are adjacent to high current equipment with elevated AC magnetic fields present. Often these field levels are sufficient to cause interference with sensitive equipment, etc. In some instances, passing utility power distribution or transmission lines can also cause elevated AC magnetic fields inside adjacent buildings.

The presence of RF or radio frequency EMF inside certain buildings from near by communication antennas can cause interference with wireless networks, communications equipment and other sensitive electronic systems. External RF signals can be especially troublesome in special use buildings, such as hospitals, research laboratories, broadcasting studios, where they can cause serious interference problems with sensitive medical, research, recording equipment, etc. Sometimes, RF sources inside buildings, such as handheld two way radios, etc. can cause EMI problems with sensitive equipment.