The IEC 61111 Class 4 electrical rubber mat is the highest-rated insulating mat under the IEC 61111 standard. It is designed for very high-voltage environments where the working voltage reaches up to 36,000V AC. If you operate 33kV substations, ultra-high-voltage switchgear rooms or transmission-level equipment, the Class 4 mat is the mandatory choice for floor-level electrical insulation.
This article covers everything you need to know about the Class 4 insulating mat such as its technical specifications, applications, material properties, installation requirements, and the most common buyer questions.
What is an IEC 61111 Class 4 Electrical Rubber Mat?
The IEC 61111 Class 4 electrical rubber mat is the top-grade elastomer floor mat in the IEC 61111 classification system. It provides insulation protection for workers in electrical environments where voltages can reach up to 36,000 volts AC.
This mat is proof tested at 40,000V and must withstand a remarkable 50,000V during the dielectric withstand test, making it suitable for the most demanding high-voltage installations.
Key Voltage Ratings for Class 3:
| Specification | Value |
| Max Use Voltage (AC) | 36,000 V |
| AC Proof Voltage | 40,000 V |
| Withstand Voltage | 50,000 V |
| Recommended Thickness | 5.0 mm |
| Max Thickness Allowed | 14 mm |
| Standard Length | 10 m |
| Standard Width | 1.0 m |
Where is IEC 61111 Class 4 Mat Used?
Class 4 insulating mats are used at the highest end of the voltage spectrum. They are essential in:
- 33kV electrical substations and switchyards
- Extra-high-voltage (EHV) power plant control and transformer areas
- Grid-level switchboard rooms and distribution centres
- High-voltage testing facilities and laboratories
- Transmission and distribution infrastructure at 33kV and above
- Railway traction substations at high-voltage levels
- Industrial facilities with very high-voltage drives and transformer installations
- Cable trench and busbar areas in utility-grade power stations
Any electrical environment at or near 33kV must use a Class 4 mat. No lower-class mat is adequate for these voltage levels.
Material and Design Features
At 5 mm thick and with a withstand capacity of 50kV, the Class 4 mat is the heaviest and most robust insulating mat in the IEC 61111 family:
- Premium elastomer: Natural rubber and synthetic polymers with no insertions
- 5.0 mm recommended thickness: For maximum insulation performance
- Fine ribbed anti-slip top surface
- Textured anti-skid underside to ensure stability on the floor
- Flame retardant: Certified not to catch fire
- Resistant to mild acids, alkalis, oil, water, and moisture
- Ozone and UV stable for long operational life
- Standard IEC marking every meter: Which shows class, voltage, and product name
- Operating temperature range: -25°C to +55°C
Technical Specifications of IEC Class 4 Electrical Mats
| Technical Property | Performance Value |
| Material | Elastomer – Natural Rubber + Synthetic Polymers |
| Mechanical Puncture Resistance (min) | 70 N |
| Slip Resistance (min) | 50 N |
| Flame Retardance | Does not catch fire |
| Low Temperature Test (-25°C) | No visible tears or cracks |
| Acid Resistance | Mechanical values ≥ 75% of original |
| Oil Resistance | Mechanical values ≥ 75% of original |
| Aging at 70°C for 168 hrs | Puncture resistance ≥ 80% of original |
| Weight per Roll (10m x 1m) | Approximately 72 kg |
Complete IEC 61111 Class Comparison
Here is a complete overview of all five IEC 61111 classes to help you make an informed decision:
| >Class | >Max Voltage | >Proof Voltage | >Withstand Voltage | >Thickness | >Weight |
| Class 0 | 1,000 V | 5,000 V | 10,000 V | 2.0 mm | 32 kg |
| Class 1 | 7,500 V | 10,000 V | 20,000 V | 2.0 mm | 32 kg |
| Class 2 | 17,000 V | 20,000 V | 30,000 V | 3.0 mm | 40 kg |
| Class 3 | 26,500 V | 30,000 V | 40,000 V | 4.0 mm | 56 kg |
| Class 4 | 36,000 V | 40,000 V | 50,000 V | 5.0 mm | 72 kg |
Why Class 4 Mats Require Extra Attention?
Because Class 4 mats are used at the very high end of voltage tolerance, they demand extra care in handling, inspection, and maintenance:
- Always verify the class marking on the mat before installation in a 33kV environment.
- Inspect thoroughly before and after each use. Even minor physical damage must be taken seriously.
- Store correctly: Roll the mat loosely or lay it flat. Never fold it.
- Annual dielectric re-testing is strongly recommended for all Class 4 mats.
- Never use a Class 4 mat that has not been tested within the last 12 months in a live 33kV environment.
- Always used in conjunction with appropriate Class 4 PPE, insulating gloves, safety boots, and arc flash rated equipment.
Customisation Options for Class 4 Mats
Like all classes under this product range, Class 4 mats can be customised:
- Thickness: Up to 14 mm for additional insulation margin.
- Width: Up to 1220 mm (4 feet) for wider coverage areas.
- Length: Up to 15 m per roll for large switchgear rooms.
- Colour: Standard black, with dark grey and other colours available subject to feasibility.
- Surface design: Top and bottom textured design available as an alternative.
For bulk orders above 300 sq m, customised quotes with the best pricing are available directly from the Duratuf.
Conclusion
The IEC 61111 Class 4 electrical rubber mat is the ultimate insulating floor mat for very high-voltage environments at 33kV and above. It is a non-negotiable safety requirement in such settings. Always ensure your Class 4 mat is sourced from a certified manufacturer, comes with a full test certificate, and is inspected before every use.
