How does the UL standard influence control cabinet design?

Project engineer Jarno Viikisalo knows the requirements of the UL 508A standard. ”Selecting the right kind of components is essential,” explains Jarno.

Electrical design of a UL-approved cabinet requires thorough familiarization with the standard

The UL 508A standard (Industrial Control Panels) in use in the U.S. market pertains to the electrical safety of industrial control cabinets. The standard applies both to each phase of the electrical design of control cabinets as well as to the manufacture and inspection of these products. In Canada, the corresponding standard is CSA C22.2.

What do you need to know when starting to design a control cabinet?


Jarno Viikisalo, Project engineer

Makron’s project engineer Jarno Viikisalo is familiar with the requirements of the UL 508A and CSA C22.2 standards. ”In control cabinet design, selecting the right kind of components is of critical importance,” shares Viikisalo. The requirement for UL approval for the component, specifically pertaining to its use in the portion of the circuit in question, guides the selection. There is also a specific AWG standard that applies to conductors.

To begin design of a UL-approved control cabinet, you need certain information, for instance, concerning the voltage to be used, the current of the largest motor, maximum heating and device location. Location determines the required NEMA Type enclosure rating used in North America instead of the IP code defined in the IEC standard. The voltage options also differ from the European system. Based on the initial data, we will be able to select suitable UL-classified components for the control cabinet.

Cabinets are designed to be safe

When designing a control cabinet, you must consider the space needed for instance by bent conductors, which means that the components need to be installed at wider intervals. Work instructions prepared for UL-approved control cabinets are observed while manufacture and inspection take place according to the specific processes defined. A data plate indicating the details required by the standard, along with the necessary warning signs will be attached to the product.

Control cabinet details are carefully documented

The UL standard places strict requirements for traceability and documentation of a product. Each control cabinet has a unique serial number on the UL label attached to the product. The requirement for documentation also concerns the manufacturing phase: all of the components used in building the control cabinet, including conductors, must be traceable.

Designers develop their skills

Makron is a control cabinet designer and manufacturer approved by Underwriters Laboratories and holds the UL 508A and UL-CSA C22.2 certificates. We have been trained in the requirements of the standard and the principles of UL-conformant design, and we work continuously to deepen our knowledge. ”Studying the UL standard has been highly interesting and posed a new type of a challenge,” notes Jarno Viikisalo.

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