What Does an Earthing Mat Do for Electrical Work?

An earthing mat, also known as a grounding mat, is a special mat used in electrical work to provide a safe path for stray electrical currents into the earth. Earthing mats protect electricians and electronics from electrostatic discharge and electric shocks. This article explores what an earthing mat is, how it works, and its importance in electrical work.

What Is an Earthing Mat?

An earthing mat is a durable, conductive rubber mat that provides a connection between a person, equipment, or workspace and the earth. It features a grounding plug or clip that connects the mat to a verified earth, such as a home or building’s earthing system.

Earthing mats used for electrical work are designed to safely direct electrical currents away from equipment and workers. They prevent build up of static electricity that could damage sensitive electronics. They also protect workers from stray currents by equalising electric potential between them and earth.

Quality earthing mats are sufficiently conductive to maintain a safe, uniform potential gradient. They are also thick and durable enough to lie on, stand on, or place electronics on. Common sizes range from small personal mats to full anti-static floor mats covering a large workspace.

Why Earthing Is Critical for Electrical Work

Earthing is a fundamental safety practice in any electrical work for the following reasons:

• Prevents electrostatic discharge (ESD) – Friction can cause static build up on workers and equipment. ESD can destroy sensitive electronics without proper grounding.
• Protects from electric shocks – If a worker becomes part of an electrical circuit, earthing directs the current safely into the ground instead of their body.
• Lightning protection – Earthing guards against damage from lightning strikes by providing a path to earth for the high currents.
• Shields electromagnetic interference (EMI) – EMI can disrupt electronics. Earthing shields equipment by keeping casing at earth potential.
• Dissipates stray currents – Earthing prevents build up of small stray currents that could harm workers or electronics.

Earthing also improves the safety, performance and longevity of electrical systems and equipment. It is a fundamental practice mandated by electrical codes and regulations worldwide.

How Does an Earthing Mat Work?

An earthing mat works by providing a low-resistance path from a conductive surface to the earth. This equalises electric potential between the surface and earth, providing stabilisation.

The mat is made of conductive rubber or carbon impregnated fabrics. When plugged into an earthing point, this creates a closed circuit from the mat’s surface through earth and back, allowing charges to drain away.

The mat is placed on a solid floor surface or foundation that has been permanently earthed. This could be a concrete slab or floor with an embedded earthing grid or grounding rods.

When a worker stands on the mat, any build up of static electricity on their body can discharge safely into the mat and earth. The same occurs for electronics or other equipment placed on the mat’s surface.

If a live wire ever comes in contact with a worker or device earthed to a mat, dangerous currents are shunted into the ground instead of through personnel. This protects from severe electric shock.

Proper installation, grounding electrodes, maintenance, and testing ensures an earthing system like a mat provides continuous, low-impedance connection to earth at all times. This is critical for reliability and safety.

Why Earthing Mats Are Essential in Electrical Work

Earthing mats serve several indispensable purposes that make them standard equipment in any professional electrical work:

Worker Safety – The mat protects workers from electrocution by directing wayward currents into the ground. This prevents electrical shock injuries.

Fire Prevention – ESD can spark fires. Earthing prevents static build up that could ignite flammable materials.

Equipment Protection – ESD from improper grounding can instantly fry sensitive electronics and computers. Mats prevent this.

Data Accuracy – EMI negatively impacts instrument readings. Earthing guards accuracy and precision in electrical testing.

Compliance – Use of earthing mats satisfies mandated safety standards. This covers liability and qualifications for electrical projects.

Reliability – Proper grounding enhances stability and reduces downtime of systems from stray currents or lightning strikes.

While simple, the earthing mat provides reliable protection that enables all other aspects of safe electrical work. No professional should skip this fundamental precaution.

Proper Use of Earthing Mats in Electrical Applications

To ensure safety and efficacy, earthing mats must be used properly in electrical contexts:

• Install mats on a solid, permanently grounded floor surface able to serve as an earthing plane.
• Only connect mats to verified, dedicated earthing points traceable to grounding electrodes or building earthing.
• Securely fasten all connections to ensure a low-impedance, long-lasting connection to earth.
• Cover large work areas by joining adjacent mat sections together securely or installing full floor mats.
• Limit mat movement by taping down edges. Check for tripping hazards from mats and cords.
• Keep the mat’s surface clean and dry. Avoid chemical spills which could degrade the mat over time.
• Conduct routine inspections of mats and grounding connections to check for damage or excessive wear.
• Test earthing resistance at least annually and whenever changing setups using an earth ground tester. Resistance should not exceed guidelines for the type of work.

Proper installation, maintenance and testing verifies earthing mats provide continuous, low-resistance connection to earth needed for electrical safety.

Key Standards and Guidelines for Earthing Mats

Those utilising earthing mats for electrical purposes should adhere to relevant standards and regulations, including:

• BS 7671:2018 – The UK’s wiring regulations mandate earthing systems to prevent electric shock.
• BS 7430:2011 – Provides code of practice for protective earthing in electrical installations.
• BS EN 61340-5-1:2016 – Covers requirements for electrostatic control workstations including earthing.
• IEC 61340-4-1:2015 – International standard for testing conductivity of earthing mat materials.
• ANSI/ESD S20.20 – American standard covering earthing requirements in ESD protected areas.
• NFPA 70E – US codes for earthing and use of mats as protective equipment for electrical safety.

The above should guide minimum performance and testing specifications when selecting and installing earthing mats for electrical purposes. Consult all relevant local codes as well.

Key Specifications When Selecting Earthing Mats

Those purchasing earthing mats should evaluate products based on key criteria:

• Conductivity – Ensure materials provide sufficiently low resistance, typically less than 10^9 ohms.
• Durability – Mats must withstand workplace conditions and maintain integrity over years of use.
• Size – Mats must cover all necessary work surfaces and allow workers to stand fully on them.
• Quality – Select commercial-grade mats from reputable suppliers, avoiding any defects.
• Certifications – Look for mats certified to relevant safety standards for grounding equipment.
• Visual Markings – Mats should be clearly marked for safety and have visible grounding points.

Consulting with qualified electricians helps identify appropriate mat specifications and ratings to meet your electrical safety needs.

Applications of Earthing Mats in Electrical Work

Earthing mats find ubiquitous use across nearly any electrical work context:

• Electronics repair – Protects delicate electronics from ESD during troubleshooting and soldering.
• Circuit assembly – Prevents ESD damage when assembling PCBs and electronic devices.
• Wiring and cabling – Mandatory for electricians to prevent shocks when working on live systems.
• Telecommunications – Safeguards telecom equipment from lightning strikes when installing antennas and networks.
• Electrical testing – Ensures accuracy of readings by preventing interference from stray currents.
• Server rooms – Guards computer equipment against ESD and EMI in data centres.
• Appliance repair – Protects repair technicians and prevents appliance damage from electric shocks.
• Electrical labs – Provides critical researcher protection when experimenting on live circuits.

Any tasks involving open, live electrical connections requires proper earthing protocols including use of mats to prevent injuries.

Earthing Mat Materials Used in Electrical Work

The conductive medium within the mat determines characteristics like durability, conductivity, and cost:

• Rubber – Most common and affordable option. Made by impregnating rubber with carbon. Not as conductive as other materials but highly durable.
• Polymer – Polymers like vinyl impregnated with conductive fillers like carbon. More costly but very conductive and resistant to hazards.
• Metal – Made by inserting conductive metals into foam. Very conductive with excellent ESD protection but less flexible.
• Carbon – Woven carbon fibre mats offer high conductivity and easy portability. However, less durable than rubber.
• Cotton – Cotton fabric rendered conductive via manufacturing processes. Absorbent properties limit electrical uses.

Rubber, polymer, and metal mats are most common in demanding electrical applications where maximum durability and conductivity is paramount.

Takeaway on Earthing Mats for Electrical Work

Earthing mats serve as a critical safety and preventative tool for any electrical work. They protect workers from dangerous shocks while safeguarding sensitive equipment from damage due to ESD or EMI. Proper installation, grounding, and maintenance ensures earthing mats provide reliable, low-impedance connection to earth when it matters most. All electricians and anyone working with live electrical gear or electronics should utilise earthing mats as a fundamental safety precaution.