ASTM D178 Class 3 Insulation Mat (26500V Switchboard Mats)

An ASTM D178 Class 3 insulation mat is a heavy-duty electrical safety rubber mat designed for high-voltage environments where working voltages reach up to 26,500 volts AC. Certified under the ASTM D178 standard, Class 3 mats provide a substantial safety barrier for workers in power transmission substations, high-voltage switchyards, and large-scale industrial electrical rooms.

Class 3 mat sits between Class 2 mat and Class 4 mat in the ASTM D178 classification system, offering robust protection for the 22 kV to 26.5 kV range commonly found in power distribution networks and heavy industries.

Technical Specifications of Class 3 Switchboard Mats

 Where is a Class 3 Insulation Mat Used?

Class 3 mats are specified for high-voltage installations typically found in:

• Power transmission substations operating at 22 kV to 33 kV.
• High-voltage switchyards and outdoor switching stations.
• Primary distribution substations in urban power networks.
• Oil and gas production facilities with high-voltage drives and motors.
• Heavy industries like steel plants, aluminium smelters, cement plants.
• Railway traction power substations (25 kV systems).
• Large data centres with dedicated 22 kV primary supply.
• High voltage testing laboratories.

In many countries, the primary grid distribution voltage is 33 kV. Class 3 mats (rated to 26.5 kV max use) are the specification of choice when workers access 22 kV and 33 kV infrastructure with appropriate voltage controls and switching.

Why 9.5 mm Thickness Matters in Class 3 Mats?

At 9.5 mm, Class 3 mats are significantly thicker than Class 2 (6.4 mm) for important reasons:

• Higher dielectric strength: The additional rubber depth is essential to safely contain the electrical stress at 26.5 kV and withstand test voltages up to 40,000 V.
• Puncture and damage resistance: In heavy industrial environments, thicker mats are less susceptible to damage from heavy tools, foot traffic, and equipment.
• Anti-fatigue properties: A 9.5 mm mat significantly reduces leg and foot fatigue for workers standing for extended periods, an important ergonomic consideration in maintenance operations.
• Roll weight consideration: At approximately 140 kg per roll, Class 3 mats require proper handling equipment and at least two people during installation.

Type I vs Type II: Class 3 Electrical Mats

Class 3 environments like power transmission and heavy industry  are often exposed to more vulnerable conditions than lower classes. Here is when to choose each type:

• Type I: For dry, indoor high-voltage switchgear rooms and substations without chemical exposure.
• Type IIA (Ozone Resistant): For outdoor substations or rooms with ozone-generating equipment such as large transformers and arc switchgear.
• Type IIB (Flame Resistant): For areas where arc flash or fire risk is present alongside high-voltage equipment.
• Type IIC (Oil/Water Resistant): For transformer rooms, oil-filled switchgear areas, and cable trench zones.

A combined Type IIA+B+C mat is available for the most demanding environments.

AmeriVolt’s High-Voltage Project Credentials

Duratuf AmeriVolt has successfully supplied high-voltage insulating mats to some of the world’s most reputed projects, including:

• Marjan Oil Field Development, Saudi Arabia
• Qatar Gas North Field Expansion (NFPS) Phase II
• Buzios Oil Field P-79 FPSO, Brazil
• Abu Dhabi International Airport Midfield Terminal

These projects required mats capable of withstanding harsh environmental conditions, heavy foot traffic, and demanding electrical safety standards, exactly the environment Class 3 mats are engineered for.

Features & Benefits of AmeriVolt Class 3 Mats

Here are some important features of ASTM Class 3 rubber mats:

• Dielectric withstand tested at 40,000 V and providing a strong 50%+ safety margin above working voltage.
• Proof tested at 30,000 V across the entire mat surface before dispatch.
• Test certificate provided with every supply batch.
• 9.5 mm thickness delivers superior anti-fatigue comfort and mechanical durability.
• Ribbed anti-slip surface on top; anti-skid texture on the bottom prevents movement.
• Every metre marked with class, voltage ratings, and product name.
• Tensile strength min. 4.83 MPa; elongation at break min. 250%.
• ISO 9001:2015, ASTM, IEC, CE, RoHS, REACH, AIRIA, ERDA certified.

AmeriVolt ASTM D178 Class 3 Insulation Mats are engineered for the most demanding high-voltage environments. With ready stock across 7 warehouses in India and the UAE, we can ship fast to your project site anywhere in the world.