Hood-Patterson & Dewar designs and engineers transmission line, substation and data center building ground grid systems to meet the requirements of the latest IEEE Std-80 or other applicable standards. Our philosophy is to minimize the buried ground conductors while designing a cost effective system that meets the applicable standards with sufficient safety margin built into the design to last the normal lifespan of the installation.
Hood-Patterson & Dewar evaluates partial or completed ground system designs to ensure compliance to the IEEE Std-80 safety requirements or other standard criteria. We provide a critical look at the planned design and enhance the design with the knowledge obtained from numerous years of experience in optimum ground grid designs as applied to critical electrical supply installations including data centers, electrical substations, electrical power plants, transmission lines, communications masts/towers, wind turbine installations, oil refineries, or other facilities.
- Site Testing of the Installation
- Comprehensive Check of the Site Soil Conditions
- Modeling of Two-Layer Soil Resistivity
- Modeling of the Ground System and Evaluation Against Specifications and/or Standards
- Recommendations for any Site Remediation to Comply to Specifications and/or Standards
Site tests can be performed within an energized system or operational plant without the need for any shut-down or disconnection from ground bonding conductors, overhead static ground conductors or other grounded items - i.e., water pipes or other system grounds.
HPD can also perform assessments of existing ground grid systems to determine if there has been any degradation of the buried ground system without excavation of the ground conductors. This is particularly useful if the grounding system is crucial to the safe operation of a particular operational and energized plant and ground bonding or system grounds are covered with concrete or asphalt and physical examination by excavation is difficult.
HPD can identify and resolve 'ghost' grounding problems such as noise on analog signals, damaged electronics, shielding issues, etc.
Hood-Patterson & Dewar performs a ground audit of an installed grounding system at critical electrical supply installations including data centers, electrical substations, electrical power plants, communications masts/towers, wind turbine installations, oil refineries, or buildings.
An audit is typically performed if problems have been experienced or if the installation is old and the client is looking to upgrade/expand or to obtain the current installation grounding status. The ground audit covers a review of the initial design by considering the ground system 'as-built' detail, the site soil resistivity and the latest IEEE Std-80 or other standard requirements.
Services include the provision of a ground grid model to indicate locations where the highest touch and step potential are likely to exist at the installation, the pin-pointing of any site limitations where transfer potential risks exist and identification of any problems uncovered during the audit. Each site audit report indicates the design ground resistance for the ground system installed and the actual measured system ground impedance, ground mat impedance, average site soil resistivity, and measured touch and step potential at the site. Each highlighted problem is explored and possible solutions and remediation recommendations are provided to the client, including an estimated bill of materials list.