Field Finder
Field Finder
© Enviromentor AB 1998 reg. 98.011/Eng
9
4
Measurement examples
4.1
Electric fields
Below is a suggestion as to how to measure an
electric field in a room within the frequency
range 30 Hz to 2,000 Hz.
1. Start by carrying out a preliminary measure-
ment with all the pieces of electrical equipment
switched on and make a rough estimate of what
field sources are present in the room. Draw a
sketch of the room. Then measure a number of
points at 1-3 metre intervals by taking readings
in all directions in a circle around you. Write
down the highest value measured at each point
on the sketch. Using an arrow, mark the direc-
tion in which you obtained the value you have
written down. Ideally, note the field levels
towards the ceiling and the floor.
2. Then carry out a measurement with all the
electrical apparatus in the room switched off
to get an idea of the extent of the background
fields in the room. Remember that it is probably
not sufficient simply to switch off the pieces
of apparatus - you will usually need to unplug
them in order to completely eliminate the fields.
In some cases, the background fields can be as
high as the fields from the apparatus in the room.
3. Connect the pieces of apparatus one at a time
and measure the electric fields in the directions
0
°
, 90
°
, 180
°
and 270
°
at distances of 30 cm
and 50 cm from the outer edge of the piece of
apparatus in question (see figure) or in the
direction the operator is facing. Summarise the
measurement readings in a report form. An
example of how to fill out a report form can be
found on page 12. You must not subtract the
background values of the electric fields from
the measured values. They should always be
noted as a comparison.
50 cm
50 cm
Overhead view.
Side view.
Cont.
7
References to authorities and organisations
Publication
Publisher/Author
May be ordered from
Magnetic fields and health
risks based on what we
know
The National Electrical
Safety Board
Elsäkerhetsverket
Box 1371
SE-111 93 STOCKHOLM
SWEDEN
Tel. +46 8-519 112 00
Fax. +46 8-519 112 01
Cancer and magnetic fields
in workplace
The Swedish Trade
Union Confederation
LO-distribution
Strömsätragränd 10
SE- 127 35 SKÄRHOLMEN
SWEDEN
Tel. +46 8-796 25 00
Questions and answers about
electric and magnetic fields
associated with the use of
electric power
National Institute of Environ-
mental Health Sciences and
U.S. Dep. of Energy
Superintendent of Documents
U.S. Goverment
Printing Office
WASHINGTON, D.C. 20 402
USA
Tel. +1 202-512-1800
A report of non-ionizing
radiation
Microwave News
Microwave News
Louise Slesin
P.O. Box 1799
Grand Central Station
NEW YORK, N.Y. 10 163
USA
+1 212-517-28000
+1 212-734-0316
mwn@pobox.com
