14.1 Limits for personal safety
There are international recognized limits for power wires and the appliances
connected to them, as well as various precautionary limits and recommendati-
ons. Depending on the country, professional sector or the various interest
groups, however, they all can differ significantly.
The
German
exposure limits are dictated by the Regulierungsbehörde für
Telekommunikation und Post (Reg TP, roughly: regulating body for telecommu-
nications and post), which is a subsidiary of the Bundesministerium für
Wirtschaft und Arbeit (BMWA, roughly: ministry of commerce and labour). Most
national and international bodies recognize these recommendations. They are
part of the German “26. BimSchV“ (ordinance for electromagnetic fields) and fol-
low the international ICNIRP recommendation.
The German exposure limits are intended for quadratic means of measurements
taken during
intervals of 6 minutes
and subdivided by frequency ranges.
Furthermore, there are seperate limits depending on the group of persons affec-
ted. As an example, we will use the limit for the “generic population“:
Frequency
E-field [V/m]
H-field [µT]
M-field [A/m]
Below 1 Hz
-
40.000
32.000
1-8 Hz
10.000
40.000 / f
32.000 / f²
8-25 Hz
10.000
5.000 / f
4.000 / f
0,025-0,8 kHz
250 / f
5 / f
4 / f
0,8-3 kHz
250 / f
6,25
5
3-150 kHz
87
6,25
5
0,15-1 MHz
87
0,92 / f
0,73 / f
1-10 MHz
87 / f
0,92 / f
0,73 / f
10-400 MHz
27,5
0,092
0,073
The chart on the left graphically
represents, among others, the
before mentioned formulas for H
fields over a frequency range
from 0Hz to 400MHz.
The curve
clearly indicates that the wide-
ly used, cheap broadband
testers CANNOT determine
these exposure limits properly
as they do not take signal fre-
quency into account.
14.0 Exposure limits
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