04-14-04

We have added the following new engineering services
ELF EMF STUDY OF INSTALLTION & PREMISES

The 60-Hz alternating current line frequency is defined as an Extremely Low Frequency (ELF) Electromagnetic Field (EMF). This is at the bottom of the electromagnetic spectrum near direct current and the earth's geomagnetic field. ELF electric and magnetic fields emanate from 60-Hz electric power lines, equipment, and appliances. Electric fields are only significantly elevated under high voltage transmission lines. Inside commercial buildings, the electric fields are normally below 50 V/m near unshielded 120 VAC electrical wires, and zero if the wires are shielded in conduits.

Emanating ELF magnetic fields are proportional to the AC current in wires, ground conductors, metal water pipes, HVAC metal ducts, or any conductive material where a current travels. Very high current sources emanate very high magnetic field levels. Magnetic fields, or more accurately magnetic flux density electrostatic & electromagnetic induction levels, are measured in units of milligauss (mG). Magnetic fields are insidious.

Near transmission lines, the National Electrical Safety Code (N.E.S.C.) specifies 5 mA as the maximum allowable short-circuit current from vehicles, trucks, and equipment. The American National Standard Institute (ANSI) allows up to 0.5 mA leakage from portable household appliances and 0.75 mA for fixed appliances.

Our ELF EMF Technician studies the installation for a probable cause analysis and makes a survey with mapping instruments in three dimensions. The results are plotted to shop area of concern and suggestions are made for corrective and preventive action.