grounding equipment and method
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GROUNDING EQUIPMENT
AND METHODS
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Based on Dalziels Formula:
Human Fibrillation Threshold is: 164 mA or 0.164 Amps
So,
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The best safety precaution
is to respect/consider that all
equipment as if it couldbecome energized.
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1. Charges induced on the line by a neighboring energized line
Source of Hazards
2. A fault caused by an accidental contact on flashover between the
line and neighboring energized line.
3. Induced static charge due to atmospheric conditions.
4. An error in which the line is accidentally energized
5. A lightning strike to the line.
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Protection to Personnel
The means of providing personnel protection
may take several forms. These may includethe insulation or isolation of workers,
provision of an equipotential zone around the
workers or provision of a low resistance path
to ground to induced charges or faultcurrents and limit touch and step voltages to
a safe level.
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Electromagnetic
Induction
- Occurs when angrounded open
conductor picks up an
induced voltage from an
energized lineparalleling or
perpendicular to the
line.
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Grounding Devices
All grounding devices must be sized to carry the largest fault current tobe encountered for a time period long enough to allow the line
protection system to operate.
Grounding devices include the following:
1. Personal grounds2. Master grounds
3. Structure base grounds
4. Running grounds
5. Grid grounds
6. Ground rods
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Grounding System Considerations
1. Care of grounding equipment
inspection should be made prior touse grounding equipment to check for loose or dirty connections,
broken wire strands and seized clamps.
2. Grounding conditions the effectiveness of various ground sources
will vary depending on the equipment to be grounded. So, it mustbe determined first what particular ground to be implemented in a
certain area.
Warning guy wires should not be used as ground source.
3. Cleaning of Connections all surfaces to which a grounding clamp is tobe cleaned to ensure proper contact since grounding systems
depends on a low resistance path.
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5. Ground Grid Application all grid conductors and ground rods mustbe interconnected and all equipment, structures, anchors, metallic
pulling lines, conductors and overhead ground wires within the area
should be bonded to the grid.
4. Grounding Application grounding cables must be connected to the
ground source first, then to the object being grounded. Whenremoving grounds, the ground must be removed from the grounded
object first and then from the ground source.
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