HORIZONTAL EARTH ELECTRODE
Buried about 40 to 100 cm below grade. Generally used where soil conditions are
poor and there is no improvement in the soil resistivity at depth. Bed rock is near
the surface and the use of deep driven earth rods is impractical . With long horizontal
conductors, reactance increases as a factor of length with a consequent increase in
impedance. Thus for lightning protection use a crow foot type earth.
To lower the resistance on this type of earth electrode, install with E-Mix Conductive
Earthing Compound. This is a conductive material and will retain some moisture.
DEEP DRIVEN EARTH ELECTRODE
Buried conductor about 50 cm below grade and where the bed-rock is deep and allows
earth rods to be driven to depths of 3 to 4 m. Generally used where soil conditions are
good and the soil resistivity at depth is better than nearer the surface. Ideal for a “ring
type earth.
To lower the resistance on this type of earth electrode, install the earth rods and
conductor with E-Mix Conductive Earthing Compound. This is a conductive material
and will retain some moisture.
GRID EARTH ELECTRODE SYSTEM
Grids are generally required only in antenna farms or substation yards and other areas
where very high fault currents are likely to flow into the earth and hazardous step
potentials may exist or soil conditions prohibit installation of other ground
systems. Grid systems, consisting of copper cables buried and earth rods forming a
network of squares, are used to provide equipotential areas throughout the facility
area. Such a system usually extends over the entire area. The spacing of the
conductors, subject to variation according to requirements of the installation, may
normally be 0.6 to 1.2 m between cables. The cables must be LECTROWELDed
together at each crossover point.
STEP AND TOUCH POTENTIAL EARTH MATS
A close grid earth mat, consisting of copper cables buried about 15 cm below grade and
forming a network of small squares, is used to minimise the dangerous step and
touch potential voltages to safe levels for personnel. Installed in immediate area of
switch rods and other areas where personnel may be exposed to ‘live’ electrical plant.
All cables must be LECTROWELDed at each cross over point.
CROW FOOT EARTH ELECTRODE SYSTEM
Good for lightning protection as radials are short and keeps impedance low. Earth rods
may be attached to the ends of the radials. |
