Why EMF? World population growth and its trend to computerize everything in the globe, which can be easily noticed from the quantity and type of internet-dependent appliances i.e. smart phones, tablets, many type of laptops and personal computers are invading our normal life, where most of known manufacturers are racing to provide the globe markets with the highest technology, and all of these devices are power-dependent which found their way to the end users with high demand.

1. The Influence of Electro
Magnetic Field on Data Center
By Tarek Fawaz,
Lead Consultant - Data Center Engineering Services

2. For more information about Edarat Group
www.edaratgroup.com
info@edaratgroup.com
Why EMF
World population growth and its trend to computerize
everything in the globe, which can be easily noticed from
the quantity and type of internet-dependent appliances i.e.
smart phones, tablets, many type of laptops and personal
computers are invading our normal life, where most of
known manufacturers are racing to provide the globe mar-
kets with the highest technology, and all of these devices
are power-dependent which found their way to the end
users with high demand.
To provide a worthy reliable facilities to manage such
growth demand, it was noticeable lately that the world
trends to have high reliable facilities started with computer
rooms, server rooms, data centers and later called clouding
and colocation, including the IT virtualization, all of such
demands and need for high power density requirement
per square meters and might exceed 15 kW per rack
(around 42 KW per square meter), this means that such
building or even the square meter will require high current
flow, and by consequence high EMF as we will explain
later on.
One of the most factors affecting the performance of a
data center is the Electro Magnetic field EMF or EMC
(Electro Magnetic Compatibility) as defined by IEC
(International Electrical Code)
The EMF is created by voltage or/and current, electrical
field created by voltage and measured in V/m and magnet-
ic field by current and measured by Tesla or Gauss; the
small power in low voltage facilities, when creating electri-
cal field is constant and will not affect the facility’s equip-
ment as we will see in the following paragraphs, therefore,
the magnetic field is the only factor will affect electronic-
based equipment i.e. Blade Servers, Servers, Switches,
Routers, PCs, etc.
Sources of EMF.
The EMF will be caused either naturally or by human-made
Naturally where the earth magnitude field is measured to
be around 0.5 mG.
Besides to the natural sources the electromagnetic field
also includes fields generated by human-made sources:
such as X-rays, The electricity that comes out of every
power outlet with low frequency, various kinds of higher
frequency like radio-waves, whether via TV antennas, radio
stations, GSM sites, Microwave links, HV/MV overhead and
underground power line transmission and finally LV high
current flow of carrying current conductors inside the facili-
ty.
In our article we will present the effect of EMF caused by
high current flow inside a data centers or mission critical
facilities, having in mind that the mission critical facility loca-
tion took into consideration the outside EMF during the site
selection and was avoided to be near HV/LV power trans-
mission lines, Electrical Generating and substation, GSM or
radio station, etc.
Note that the Electric filed can be easily shielded by con-
ducting objects such as trees and buildings while the mag-
netic field is not easily shielded by most materials.
International Standards and Norms
All international standards had specified the effect of EMF
on Human and equipment I.e. EN/BS 61 000-4-8,
EN55022, EN 55011, WHO (World Health Organization),
NIEHS (National Institute of Standards and Technology),
ICNIRP (International Commission on Non-Ionizing Radiation
Protection), etc.
IEC 61000-4-8 had defined that the equipment must be
immune to magnetic field up 37.5 mG while NCRP/HPA
defined that human-body exposures to EMF should not be
less than 10 mG, and less than 4 mG in other countries by
WHO.
General Information: Germany was the first nation to adopt
a national rule on EMF exposure on January 1997
EMF measurement and its influence on
IT equipment
Following Biot–Savart law we will have the magnetic basic
formula B = f(i) = (µ_0 I)/2πR
(µ_(0: )permeability 4π〖10〗^(-7) NA^(-2),I: Current in A,R
ditance between Source of EMF in m,and point of measurement )
From the above formula the magnetic field is proportional
to the current and inversely proportional to the distance.
We conclude that the Magnetic Field will strengthen when
the current will be increased and its strength decreases
rapidly with increasing distance from the source.
As described earlier that with this high demands on IT
based equipment with the obvious trend to have Coloca-
tion facilities or cloud facilities with high density up to 15
KW per rack (and might be above), then we can deduce
that the branch of the carrying current conductor (Single
Phase) feeding such high density racks will require 85.2 A
at 380/220 V (most of Data Racks require Single Phase
power supply) with Magnetic Field strength almost equal to
170 mG.

3. For more information about Edarat Group
www.edaratgroup.com
info@edaratgroup.com
To have a tangible understanding of such values, we will
refer to the following table which illustrates the magnetic
field in mG at approximately 1m from the source of EMF of
the carrying current of three different methods, calculated
based on Biot–Savart law
The above table indicates that a 100 A (17.6 KW rack) sin-
gle phase conductor will produce at 1m a 200 mG which
is not in accordance with the standards and definitely will
affect the performance of the IT equipment exposed to
such current.
By having an average Rack with around 4 Kw or 23 A, will
create 46 mG at 1m from the conductor and still is not in
accordance with the international norms and strictly re-
quires a certain measurement to be taken to cancel such
effects.
Just imagine a bad design or construction allow to pass a
5000 Amp main cable (Three Phase) under, above or just
near enough to the data center to create such high EMF.
Conclusion:
The EMF is a critical parameter which will affect the perfor-
mance of such critical facilities, and will definitely require
specialists to provide solutions to cancel such EMFs.
Rating A
Single case
cable
Three Phase
cable
Busway
100 200 70 8
500 1000 350 40
1000 2,000 700 80
2500 5,000 1,700 200
5000 10,000 4,500 400