UL marks


All electrically controlled devices or systems in the USA must be approved. Conformity with national safety regulations is demonstrated by a mark of conformity from a qualified, recognised testing laboratory.

The most widely recognised testing laboratory is UL (Underwriters Laboratories). UL conducts tests according to UL standards, which incorporate national standards as an essential component.


UL standards for the certification of Festo products:

  • Electrical and mechanical hazards in the case of electrical products
  • Housing materials and insulation materials in the case of fire-protection tests
  • Valves: bursting pressure test at 5x the rated pressure
  • Inspection of production facilities by UL


Further information about the various UL marks which appear on Festo products can be found on the tabs below.

Is the UL mark required by law?

No, there is no law which makes UL certification mandatory.
All electrically controlled devices or systems in the USA must be approved. The legal basis for this is constituted by regulations such as those of the Occupational Safety and Health Act (OSHA Article 29 CFR 1910.xxx; CFR: Code of Federal Regulations) and the National Electric Code (NEC). In Canada, the regulations concerned are those of the Occupational Health and Safety Act (OHSA) and the Canadian Electric Code (CEC).

Due to the federal structures of the USA and Canada, different editions of the NEC or CEC apply in the different states and provinces, with the addition of individual supplements. One of the reasons for this is the different climatic conditions in individual states.

Conformity to national safety requirements can be verified by “listing” or “labelling”. Listing or labelling is the issuing of a mark or symbol (such as the “UL mark”) by a qualified Certification Organization (CO) confirming that appropriate testing has been carried out and that a piece of equipment or system conforms to the relevant safety regulations or is suitable for a specific purpose. The manufacturer can then make use of this mark or symbol. In the USA, qualified COs are test laboratories recognised by the OSHA, named “Nationally Recognized Testing Laboratories” (NRTLs). In Canada, “Certified Bodies” (CBs) are named by the Standards Council of Canada (SCC).

One of these NRTLs, and probably the best known, is UL. UL stands for “Underwriters Laboratories”, in other words the testing laboratories of insurance companies. UL conducts tests according to UL standards, which incorporate national standards as an essential component. The ultimate purpose of these tests is to minimise the risk posed by insurance companies' liabilities resulting from equipment and the hazards associated with it (electric shock, fire and mechanical injury). The damages awarded by courts in the USA can easily reach levels high enough to threaten the continued existence of manufacturers, sellers and users (companies).

Who takes notice of the UL Mark?

The measures necessary to achieve conformity with national safety requirements vary depending on the relevant application. Electrical equipment and systems are inspected on site. The responsibility for carrying out these inspections lies with the “Authority Having Jurisdiction” (AHJ). The UL mark simplifies the inspection process for the local “Authority Having Jurisdiction” (AHJ), helping to avoid delays during system commissioning and the high cost of any modifications to installations which might otherwise be necessary.

According to which UL standards are Festo products certified?

Electrical products are tested for any electrical and mechanical hazards. In the case of flammability tests, assessment also includes the housing materials and insulating materials. In the case of valves, bursting pressure testing is also carried out, at five times the rated operating pressure. UL conducts inspections of production facilities at regular intervals. This ensures that products maintain the form in which they were originally tested.

Do connecting cables need to be UL-certified?

Because of their intended use, many Festo devices are certified as devices for “Class 2 Circuits”. “Class 2 Circuits” are energy-limited circuits with a maximum voltage of 30V AC or 42V DC, a maximum current of 5A and a maximum power rating of 100 VA. According to the UL definition there is no danger of either electric shock or fire in these cases. UL certification is thus not required for plugs and cables. In the case of devices not rated as for “Class 2 Circuits”, certification is required for the cables used.

What do the UL marks on Festo products mean?

UL is authorised to carry out certification in accordance with both US safety regulations (NEC) and Canadian safety regulations (CEC). This is indicated accordingly by the particular UL mark. The C-UL-US or C-UR-US marks take the place of CSA certification for Canada.

UL Online Certifications Directory

UL Certification Directory

You want to know whether a product has an UL certification?
Use the query option of the UL Online Certifications Directory.

Necessary entries:
Company Name: Festo
Keyword: Festo series name with * e.g. SIEN*