BRS was approached by RCS Telecommunications to provide RPEQ earthing designs for several radio tower and communications hut sites across Central Queensland.
Soil resistivity tests were conducted across all sites using the 4 point Wenner test method. From these results, BRS were able to model the soil resistivity for each site in SKM’s GroundMat software and evaluate several different earthing design variations for each site:
Diameter, length, number of, and material type of earthing rods;
Diameter, length, number of, and material type of buried earth conductors;
Consideration and use of earthing enhancing compounds (eg. bentonite, GEM25 etc).
In addition to the earthing designs, prospective fault currents, as well as, touch and step voltage calculations were also performed and evaluated in relation to personnel safety for all infrastructure at each site. The earthing design was then tweaked, as necessary, to ensure any touch and step voltages during a prospective fault would be deemed tolerable.
Through a reciprocating process with RCS, BRS were able to produce earthing designs for each site to suit not only the site soil conditions but, also overcome any barriers to physical installation which included:
Rocky ground;
Existing infrastructure;
Poor soil resistivity;
Impractical and/or uneconomical number of earthing conductors;
Applicable standards:
AS/NZS 3000:2007 Wiring Rules
AS/NZS 1768:2007 Lightning Protection
IEEE Standard 80 Guide for Safety in AC Substation Grounding
