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Bonding & Grounding |
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Bonding is simply a
matter of taking all of the electrical and metallic masses in a facility
and connecting them with conductors, bringing them to the same
electrical potential. The primary reason for bonding is personnel
safety, so someone touching two pieces of equipment at the same time
does not receive a shock by becoming the path of equalization if they
happen to be at different potentials. |
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For the same reason
bonding protects people, it protects equipment, by reducing current flow
on power and data conductors between pieces of equipment at different
potentials.
Grounding is a matter of
bringing the bonded equipment mass to the potential of the surface of
the earth which it occupies. Again, the primary reason is personnel
safety, and the secondary reason is equipment protection. When it comes
to grounding, we need to consider two types of grounding: low-impedance
grounding of structures, and single-point ground potential referencing
for services and equipment |
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LOW-IMPEDANCE STRUCTURAL GROUNDING
A structure is anything which is likely to be struck by lightning.
Multiple low-impedance paths to the grounding system transfer lightning
energy off of the structure and into ground as quickly as possible.
Since lightning is very high frequency, low-impedance, not just
low-resistance, paths are the key. The higher the impedance the
lightning energy "sees", the greater the voltage increase. The higher
the voltages, the more likely the energy will arc or take unwanted paths
to ground. |
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Therefore, it is important
to provide multiple paths with good geometry directly to grounding
electrodes within the grounding system. |
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SINGLE-POINT SERVICES AND
EQUIPMENT GROUND POTENTIAL REFERENCING |
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Why is it that direct
lightning strikes to two similar facilities can leave one undamaged and
the other virtually destroyed?
Among all the variables
involved in system design, we have found the single most important
factor in effective lightning protection to be not simply bonding and
grounding of equipment and services, but proper connection of the
services and equipment bonding sub-system to the grounding system.
A change in potential per se does not
damage equipment. It is a difference in potential across your equipment
causing current flow through your equipment which causes damage. If the
potential of the entire system changes at the same time and rate, and
the equipment does not have any other source of ground potential
reference, there is no current flow and no damage occurs.
Current divides and takes all paths. The proportion of the current
flowing on any one path is proportional to the surge impedance of that
path relative to the total surge impedance of all paths. Even if heavy
duty bonding straps are provided between grounds as the primary intended
path of equalization, some of the current flow will be through
unintended paths; through other conductors and equipment.
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Therefore, it is critical to bring all
services and equipment grounds within a facility to the same potential
before they connect to the grounding system, eliminating the possibility
of current flow. |
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In a typical facility, we
must be concerned with several different ground potentials. |
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The first set of ground
potentials is associated with the services to the site, i.e., AC power,
TELCO, data and RF transmission lines from antennae. If a piece of
equipment is connected to both a data line and to a power supply, and
there is a difference in ground potentials between those two service
grounds, that difference in potential can equalize within the equipment,
causing damage or accelerated wear. |
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The second set of
potentials is associated with the various electrical and electronic
equipment chassis grounds. If two pieces of equipment are communicating
with one another through data line, and if there is a difference in
potential between the two pieces of equipment, that potential can
equalize through the data lines within one or both of the pieces of
equipment, (see illustration below) |
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When we refer to the
facility equipment, it is important to note that we are referring only
to electrical or electronic equipment, not door frames, air conditioning
ducting, miscellaneous masses of inductance, etc. |
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To perhaps oversimplify
the concept, envision an imaginary plane at or just below the floor
level of the facility. All of the site equipment and services should be
appropriately bonded together above this plane, and an appropriate
grounding system established below this plane. All services and
equipment grounds should pass through one and only one hole through that
plane. Therefore, all equipment within the site will be at the ground
potential of that single-point. This concept is commonly referred to as
"single point grounding", or, more accurately, "single point ground
potential referencing". |
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Lightning Master grounding
solutions |
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Lightning Master offers a full spectrum of
design and upgrade services, equipment and products to help you achieve
effective bonding, low resistance and low-impedance grounding, and
single point ground potential referencing for your facility. |
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Lightning
Master can help you survey and evaluate your existing system, as well as
plan, design and install improvements. We can also help you write
specifications to assure effective and uniform practices at and between
your facilities. |
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To help you achieve
low-impedance routing of bonding and grounding connections, Lightning
Master offers low-impedance clamps and connectors, including our Tower
Leg Ground Strap (TLGS) products. |
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For use in areas of poor
soil conditions, Lightning Master offers Ώ Master™ carbon-based
grounding backfill to lower grounding resistance. This is a very low
sulfur content, environmentally safe, easy to use, cost-effective
solution, and offers an attractive alternative to chemical or other
artificial grounding enhancement schemes. |
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To provide a convenient
connection point for multiple conductors, Lightning Master offers a full
line of Bus Master™ bus bars, including bars with hole patterns
customized to your needs. |
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Again, effective
lightning protection is a three-step process involving effective bonding
and grounding, transient voltage surge suppression, and structural
lightning protection. Without all three elements you are not protected.
Proper bonding and grounding is but one element. |
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