Many components have been tried and tested over the years and provide valuable service in EU control cabinets. It therefore seems reasonable to consider using them in UL control cabinets as well. However, this can quickly lead to problems, because components for the North American market require special UL certification, which is granted by UL ( Underwriters Laboratories Inc. ).
What is behind UL certification?
In order to put control cabinets into service, they must be certified or undergo a comprehensive evaluation before use. However, this can quickly lead to problems, as CE certification is not recognized in the United States. Instead, U.S. authorities rely on UL certification. Certification by the independent organization Underwriters Laboratories—known as UL certification—is held in particularly high regard in all U.S. states.
Is UL certification required?
As a government agency, the OSHA —the U.S. Occupational Safety and Health Administration—requires that all electrical equipment and systems be either certified or undergo a thorough inspection. This requirement is based on 29 CFR 1910.303 of the Occupational Safety and Health Act, a federal law governing occupational safety and health regulations.
Due to the federal system in the United States, some states have additional requirements for the approval of products, machinery, and equipment. Compliance with the applicable regulations is demonstrated by a certification mark. UL approval is typically granted through the UL Listing Label for representative samples of a product or the UL Recognized Label for the approval of individual components or parts with specific usage or installation requirements.
Is UL certification required by law?
This might lead one to believe that UL certification is required by law, but that is not the case. The listing label can be affixed by any accredited testing laboratory. However, Underwriters Laboratories is recognized not only by OSHA but also by all U.S. states as an NRTL (Nationally Recognized Testing Laboratory), which means that UL certification carries comparable weight and is recognized as a mark of product safety even beyond the United States.
How does a product obtain certification from Underwriters Laboratories?
In order for an electronic product to be certified with a UL mark, it must first be tested by an NRTL in accordance with the requirements of the applicable standards. This inspection is very comprehensive and covers fire and electric shock hazards, as well as explosion risks in hazardous locations. Since UL is recognized throughout the United States as a qualified testing laboratory, a UL mark provides particular assurance of approval by the relevant regulatory authority.
UL Certification for the Krayer Control Cabinet
As specialists in UL-compliant control cabinet construction, we build our cabinets in accordance with current standards and certify them ourselves following thorough testing. This eliminates the need for the costly and time-consuming certification process conducted by an NRTL. In order to be authorized to affix the labels to our control cabinets, we first had to obtain certification ourselves and pass a rigorous examination. The certificates we have earned confirm that we possess the necessary qualifications to manufacture, test, and certify control cabinets in accordance with UL standards.
This includes extensive knowledge of the use of approved materials, components, and parts. For example, all parts intended for use in a control cabinet bearing the UL mark generally require UL certification as well .
Is it permissible to use components without UL certification in a UL-compliant control cabinet?
Obtaining UL certification can therefore be quite time-consuming. So it stands to reason to install components that are already CE-certified in UL control cabinets. After all, our European standards are strict, and these components have been tried and tested over many years and perform reliably in EU control cabinets. We strongly advise against this, however, because due to the specific safety requirements in the U.S., these components must have special certification.
Even though there is no law that mandates UL certification, in practice it is nearly impossible to put control cabinets containing components without UL approval into service. There is a strong correlation between UL’s standards and testing procedures and the regulations of other U.S. institutions. For example, the National Electrical Code (NEC)—the safety standard for electrical installations in the U.S.—references UL standards and takes them into account in its ongoing development.
If a component is a custom-made, specialized, or prototype product, a Limited Production Certification is recommended. This certification, which complies with international industry standards, significantly simplifies the export process and market entry into the United States.
Components without UL certification
If a componenthas neither “UL Listed” nor “UL Recognized” certification , it can generally be concluded that this component must not be used in a UL-certified control cabinet .
- For UL Listing, representative samples of a product are tested. If these samples meet UL’s applicable safety requirements during testing, they are awarded the “UL Listed” mark. This certification is commonly referred to as “UL approval.”
- The UL Recognized certification applies exclusively to components, not to complete products. If components or materials receive the “UL Recognized Component” mark , they may be used in a product or system that already bears the UL Listed label. In that case, the entire product does not need to be tested again.
Exceptions to the Rule
However, the strict UL standard allows for exceptions under certain conditions. The competent regulatory authority in the U.S., the AHJ, plays a decisive role in this process. The AHJ inspector decides whether a system can be put into operation. If the inspector accepts components that do not have UL certification, the system is connected to the grid. If the inspector vetoes them, the system remains shut down. And this is precisely where the major risk lies for businesses that use UL components without certification . They can never be certain how the AHJ inspector will rule.
However, it is possible to clarify in advance whether the authorized inspection authority (AHJ) will accept the components without UL certification. This clarification must be made in writing. Only with written approval can the control cabinet’s compliance with the “UL-Listed” markunder UL 508A, UL 698A, or UL 1203 be confirmed.
Exception Specified in the Standard
A well-known exception, which is specified in the standard, is the use of non-UL-listed components in a Class II or Low-Voltage Limited Energy circuit. In this case, the components may have a maximum power consumption of 100 watts at a maximum of 50 volts. In addition, the circuit must be protected by an additional fuse.
If a Class II circuit is used, there are certain requirements for the component that must be strictly observed. For example, the component must not perform any safety functions, nor may it act as a sealing component on the control cabinet enclosure.
How much does UL certification cost?
Unfortunately, there is no one-size-fits-all answer to the question of the cost of UL certification. To answer this question, we must first determine what exactly is to be certified: a material (such as a plastic), a component (such as a fuse), or a complete system. Depending on the type of product being tested, different UL markings may be granted.
In addition to the target certification and the category to which the product belongs, its size and complexity also influence the total cost. Furthermore, the level of hazard plays an important role in determining the cost. Logically, the greater the effort required for UL certification, the higher the costs.
To be specific: This is how much an UL certification costs
To give you an idea of the specific costs associated with UL certification , we’d like to conclude by looking at a real-world example. One of the most complex testing processes recognized by UL is Field Labeling, in which entire machines or systems are inspected by UL. In our experience, the cost for the entire process, including a preliminary acceptance inspection in Germany, ranges from approximately 15,000 to 20,000 euros.
How much does UL certification for a control cabinet cost?
In addition to the costs of UL certification, the control cabinet itself also incurs higher costs. For one thing, the UL-compliant components that must be used and their installation in accordance with standards are usually more than twice as expensive as the parts used in an IEC control cabinet; for another, the effort required for planning and documentation is significantly greater.
When considering the entire process, from design to the certified final product, our experience shows that the price of a UL-certified control cabinet is three to four times higher than that of a standard model for the European market.
Zusammenfassung
Although not required by law, a UL-certified control cabinet is the safest way to ensure a smooth approval process by the Authority Having Jurisdiction. This is due, among other things, to OSHA requirements and the close ties between UL standards and those of other U.S. institutions. The strict requirements for UL-certified control cabinets also apply to their materials, components, and parts.
As a general rule, components without UL certification may not be used in UL-compliant control cabinets. If a machine or system is to be put into service in North America using components without UL certification, this must be clarified in advance with the AHJ at the installation site and confirmed in writing.
