In the context of trenchless engineering, ground mat in the simple sense is a flat, pliable piece of rubber matting that’s placed over the work area for workers and equipment to tread easily and safely on the ground without risk of slipping or electrically electrocuted. It’s not just any old mat; it’s specially designed for such use and it comes in a wide variety of colors and sizes to meet any specific needs you might have. There are also work benches and even tool racks that are fitted onto the mats for easy and expedient access to the various tools and equipment. It’s basically a safety net to stop your crew from falling while working on the trench, which is why most of them are made of reinforced rubber.
Now let’s come at the other end of the equation and talk about how a ground mat works in a typical electrical installation. A transformer is basically a coil of electromagnetism that’s connected to an alternating current, usually in the form of direct current (DC) or alternating current (AC). Transformer coils tend to generate enormous amounts of magnetic field that are trapped inside the casing. This captured field produces a sudden pull on the conducting metal parts, which in turn causes the resistance to develop. The problem arises when this pull is much too much for the metal part to handle so there is an electric arc or “resistance” produced which is where the rubber mat comes into play.
The resistivity develops because of the amount of alternating currents. If the current is slow-moving or medium-speed then the elasticity of the rubber material would allow some slip-free current to pass through the rubber mat without any ill effects. On the other hand, if the current is fast-moving or very intense, then the friction would cause a tremendous amount of stretching that would tear the fibers of the rubber material causing it to get damaged, especially around the contact points. It is important to know that there are more than one type of resistivity and there is also a difference between electrical and magnetic areas. Commonly used resistivity values are in the range of 0.1 ohm to five ohms.