The American UL standard is essentially the German VDE standard. The Underwriter's Laboratories were founded already in 1894 and is headquartered in Illinois, USA. UL's task is not to approve products. However this organisation tests products, components, materials and systems whether they meet specific requirements. If that is the case these products may be equipped with the UL certification label. It is subject to a charge. The UL standard applies only for the time the product complies with the specified standards.

As brand supplier of high quality safety testers for the electrical safety testing the SPS electronic GmbH, situated in Schwäbisch Hall and Twist, has acquired an excellent reputation worldwide. Since 1980 the privately owned company manufactures test systems for every requirement. Whether single device or system integrated into the automation: SPS stands for safety.

Continuity test, earth bond test, high voltage test, function test, insulation test, line leakage test and impulse winding test are the distinctive tests of each test system. Special solutions, specific to each product, are designed by SPS on behalf of the customer flexibly and on schedule.