Electric and Magnetic Fields

Electric and magnetic fields arise from the generation, transmission, distribution and use of electricity and in broadcasting and telecommunications, radar, induction and dialectic heating.

Electric Fields

Electric fields are produced as the voltage forces electricity along a wire. The higher the voltage the stronger the field produced. Electric fields around a wire only cease to exist when the appliance is unplugged or switched off at the socket. They will still exist however around the cabling within the wall or infrastructure.

The direct effects on the body include perception effects such as tingling skin, small harmless shocks and induced currents in the body that may cause adverse effect.

Magnetic Fields

Magnetic fields are created when an electric current flows. The greater the current the stronger the magnetic field. Certain items of equipment (NMR machines & MRI scanners) used within the University intentionally produce very strong magnetic fields. These may induce much larger currents in the body than electric fields and can interfere with the functions of the nervous system and light flashes may be noticed in the eye.

At frequencies in excess of 10MHz heating effects can occur and in excess of 100MHz these can lead to adverse health effects.

There are a number of indirect effects that can occur including:

• Movement (potentially violent) of ferrous metal objects in the field
• Spark discharge
• Heating and interference with pacemakers, metallic implants, etc.

The door to any room containing a powerful magnetic source should have a warning sign indicating the hazard and access should be restricted whilst the magnet is in operation.