16-04-2012, 03:59 PM
GROUNDING
Grounding Article.pdf (Size: 455.94 KB / Downloads: 47)
Introduction
Grounding and bonding are an integral part of
any modern electrical protection system. It is
crucial in ensuring personnel safety, as well as
providing reliable protection for vital equipment
and to minimise interruptions of service and costly
down time.
With almost a century of experience in the
design and manufacture of bonding and
grounding products, ERICO is the single source
provider that offers the best in long lasting, cost
effective, grounding products.
Grounding Design
Achieving an acceptable ground can be
challenging! They are often required to meet
minimum designed guidelines / conditions as
nominated by the principal or required by the
governing standard. For lightning, most standards
nominate a resistance of ten (10) ohms or less and
yet it must be noted that the impedance of the
system is a more critical factor. High voltage
electrical installations are generally designed to a
value of one (1) ohm.
Ground Electrodes
They are the means by which currents are
dissipated into the soil. Conductor can be laid in
trenches but the most common electrode is a
driven rod. This is generally steel and it is often
protected from corrosion by an electrolytically
applied layer of copper. This application method is
preferred because rods with a tubular copper
sheath are easily compromised when the sheath is
damaged in transit or torn whilst being driven into
the ground.
Soil Enhancement
The soil resistivity plays a significant role in
determining the overall performance of a
grounding system. It must be known before a
proper grounding system can be designed. In poor
soil conditions, the effectiveness of the electrodes
can be improved and a lower resistance achieved
by use of a ground enhancing material.
GEM is the ideal material for this task. It has a
resistivity 20 times lower than the typical values for
bentonite. The product is stable and sets hard. It
does not shrink during dry periods and can be
installed dry or as a slurry. In addition to this, GEM
is environmentally friendly.
Design Services
If you are still of the opinion that grounding is a
"Black Art", then why not let ERICO design your
next grounding system. Our Application Engineers
design earthing and lightning protection systems.
They are also available to conduct site surveys and
audit existing systems.