Insulating Rubber Mats — IEC 61111 & ASTM D178 Manufacturer

The class is specified first — the thickness follows from it

A mat is sized from the maximum service voltage of the installation it protects, not from the voltage a crew happens to be working at. On a three-phase circuit that normally means the phase-to-phase voltage; where the exposed part of the work is genuinely limited to one phase, the phase-to-earth figure is the one to use instead.

Once the class is settled, the standard sets a thickness window for that class. Thickness is therefore a consequence of the class, not a value you buy on its own — which is why a millimetre figure quoted without the class it belongs to cannot be checked against anything.

IEC 61111 and ASTM D178 are not interchangeable

The two standards describe the same job differently. IEC 61111 assigns the class, and separately assigns the thickness window for that class. ASTM D178 sets performance by Type: Type I is the default supply grade, while Type II covers the higher-performance elastomers.

Where a specification calls for Type II, the letters that follow it are the part that matters in a specific environment — they can be specified singly or in combination. Two suppliers can both quote to the same nominal class and still deliver different material, so the standard and the type both belong on the purchase order line.

• Insulating matting to IEC 61111 and ASTM D178
• Classes for 5 kV, 10 kV and 35 kV installations
• Available as rolls or cut sheets to the dimensions on your order
• Batch dielectric test report supplied with the shipment

What actually goes on the purchase order line

Five things cannot be guessed by a supplier: the standard and class required, the thickness required for that class, the roll or sheet dimensions, the surface finish, and whether a test certificate is needed per batch or per delivery.

The last one costs the most when it is left off, because a batch test report and a type test report are not the same document — and the difference usually surfaces when an inspector asks for the wrong one.

Storage is part of the specification

Matting that has never been used still runs out of time. Under IEC 61111, matting that has been in storage for 12 months has to be examined and electrically tested before it goes into service, even unused and still wrapped. Age is the trigger, not wear.

This is the rule most often missed at stocktake, because a storeroom full of wrapped matting looks exactly like a storeroom full of new product.