What is a Grounding Sheet?
A grounding sheet, also called an equipment grounding conductor, is a conductive pathway that protects electrical equipment and its users from electrical shocks. It ensures safe dissipation of electrical current through the ground in case of a fault, failure, or any other current leakage situations. The grounding sheet forms an integral part of an electrical system's grounding system and provides an alternative low-resistance path back to the source through the earth or ground.
Types of Grounding Sheets
Bare Copper Wire or Cable
A bare copper Grounding Sheet conductor is the most commonly used type of grounding sheet. It features a solid or stranded bare copper wire or cable without any insulation that directly connects electrical equipment to the earth grounding system. This type offers minimal resistance but needs additional safety precautions while handling.
Insulated Cable
For applications where bare copper poses a safety risk, insulated grounding cables come in handy. These feature copper conductors insulated with PVC, rubber or other jacket materials. Though more expensive than bare copper, the insulation enhances safety during installation and handling. Color codes like green help identify these conductors.
Aluminum Cable
In some cases where copper may not be available or is more expensive, aluminum cables serve as economical grounding conductors. However, aluminum has about 30% higher resistance compared to copper and needs larger conductor cross-sections to provide equivalent performance. Proper termination methods are also critical for aluminum cables.
Flexible Grounding Braids
For bonding smaller equipment like cabinets, racks, and electronic devices, flexible braided bonding straps prove convenient. Made of tinned or bare copper strands woven into a braid, they flexibly bond equipment enclosures to the principal grounding busbar or bar.
Importance of Proper Grounding
Personnel Safety
By providing a low-resistance path back to the source, grounding ensures any exposed conductive surfaces stay at or near ground potential in case of a fault. This prevents dangerous voltage build-ups that could lead to electric shocks.
Equipment Protection
Grounding shields sensitive electrical and electronic equipment from damage due to surges, faults or electrostatic discharges by bleeding off excess currents to the earth ground before they can cause component failures or ignitions.
Reliable System Operation
A proper grounding system prevents malfunctions caused by noise or interference in signal and data circuits. It maintains uniform system voltages and ensures normal, uninterrupted operation of equipment.
Lightning and Surge Protection
During lightning strikes or the switching of large inductive loads, grounding offers a safe pathway for these high currents without damage by actively bleeding off surges and redirecting them to ground.
EMI/RFI Shielding
A low impedance ground acts as an electromagnetic shield, suppressing emissions of electromagnetic interference (EMI) and radio frequency interference (RFI) that could otherwise impact electrical/electronic systems or violate regulatory limits.
Code Compliance
Adhering to electrical codes and standards is essential to ensure installation, inspection and safe maintenance. Proper grounding satisfies these compliance requirements and helps receive approval for new systems.
Grounding System Design Requirements
Equipment Grounding Conductor
This backbone conductor ties all non-current carrying equipment and structure together in parallel all the way back to the main grounding electrode. Its cross-section depends on its application but must never be less than the supply wire.
Grounding Electrode
The electrode provides a low impedance path to the actual earth ground. Common types include water pipes, ground rings or buried metal plates/rods. Multiple electrodes further reduce ground impedance.
Connections and Terminations
All connections and joints must be properly made, torqued and provided with anti-corrosion protection using items like connectors, clamps or exothermic welds for long-term reliability.
Markings and Identification
For easy identification and safety, grounding conductors are color coded green, or have a green stripe or ferrule. Proper labeling avoids confusion with other systems.
Periodic Testing
Regular testing verifies proper ground system performance and identifies defects via methods like clamp-on ammeters, fall-of-potential tests and soil resistivity checks. Corrective action maintains safety compliance over the system's lifetime.
With careful consideration of all the critical design, installation and maintenance requirements, a well-executed grounding system ensures personnel and equipment protection for any electrical network or facility. Adherence to standards minimizes safety and operational risks.
Get This Report in Japanese Language: アースシート
Get This Report in Korean Language: 접지 시트
About Author:
Priya Pandey is a dynamic and passionate editor with over three years of expertise in content editing and proofreading. Holding a bachelor's degree in biotechnology, Priya has a knack for making the content engaging. Her diverse portfolio includes editing documents across different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. Priya's meticulous attention to detail and commitment to excellence make her an invaluable asset in the world of content creation and refinement. (LinkedIn- https://www.linkedin.com/in/priya-pandey-8417a8173/)
Comments
0 comment