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Top 10 Questions About the Transition from UL 508 to IEC/UL 61810-1 for Electromechanical Relays

UL 508, Standard for Industrial Control Equipment, has evolved its U.S. based requirements for electromechanical relays to a harmonized international Standard, IEC/UL 61810-1, Standard for Electromechanical Elementary Relays.

Man standing over industrial controls panel

October 6, 2020

In today’s global economy, reducing time and cost to market is critical. With the rising demand for electromechanical relays (EMRs), understanding applicable standards, as well as necessary testing and certification requirements, can help streamline global market entry.

UL 508, Standard for Industrial Control Equipment, has evolved its U.S. based requirements for electromechanical relays to a harmonized international Standard, IEC/UL 61810-1, Standard for Electromechanical Elementary Relays. To help you better understand the transition and prepare you for successful market entry, here are the top 10 questions and answers from the webinar, 'UL 508 to IEC/UL 61810-1 Transition for Electromechanical Relays'.

  1. What is the primary difference between this Standard and IEC 60947-1 and -4-1, -4-2?

    IEC 61810-1 was developed to recognize the unique construction features and operating characteristics of relays. The webinar covered some of the unique elements of the Standard such as categories of environmental protection, special test procedures for making and breaking, markings and relay sockets. There are similarities between IEC 61810-1 and IEC 60947-1, -2, -4-1 and -4-2. These include requirements for materials and creepage and clearance.
  2. Will the SA table in 508A be updated for this CCN?  

    Yes, the SA table for 508A has been updated for the CCN "NRLC." It was updated on October 21, 2019. Download and view Supplement SA.
  3. Are these relays intended for control circuits only and that is why a short-circuit current rating (SCCR) is not required?

    These relays are intended for both power and control circuits. An SCCR is not required due to the size (rating) of the motor being controlled and where the relay is located in the circuit. Relays within equipment, such as printed wiring boards are remote from the high current source of supply. The impedance between the source and their location will significantly reduce the effects of a short circuit on the load side of the relay. 
  4. If the relay is recognized but not certified will it need to be called out specifically in the end user's file?

    That is correct for most end products. There are some exceptions, industrial control panels covered under UL 508A is one of them. Some relays may not need to be specified in the end user's file if all the conditions of acceptability can be found in the relay's recognition page in UL product iQ® on the web.
  5. Was there any consideration for allowing the native IEC requirements? Is there a basis in the National Electrical Code® (NEC®) for having to use the traditional requirements in UL 508?

    There is no basis in the NEC for having to use the traditional requirements in UL 508. The NEC covers field installation of products/equipment, not products/equipment manufactured under factory-controlled conditions. However, the NEC was not the driving force to include traditional requirements. Eliminating the traditional requirements in favor of the IEC would require relay manufacturers to recertify their products to the IEC requirements. This represents a significant burden to the manufacturers when there has been no demonstrated need to abandon the UL 508 requirements. Relays complying with UL 508 requirements are no less safe than those complying with IEC requirements.
  6. If the relays are not for field installation, then will it void a product where a relay is added in the field?

    Relays installed in the field may not necessarily affect the certification of the end-product. A relay could be part of a field-installed kit where the kit has been certified by UL. Relays can also be installed in the field as replacement parts. If the relay is one recommended by the end-product manufacturer as a direct or indirect replacement, the certification of the end-product will not be affected.
  7. Will this transition affect products under NRGU category?

    The NRGU category covers protective relays. These relays are primarily for utility applications and are covered by an IEEE standard. The transition to UL 61810-1 will not affect relays in this product category. 
  8. Are differential pressure switches within the scope of UL 61810?

    Differential pressure switches are not within the scope of UL 61810-1.
  9. Will there be any changes in the future to UL 508A? 

    Yes, UL 508A is a very dynamic Standard that is constantly changing to reflect advances in technology, changes in the marketplace and customer needs.
  10. Are there any plans to adopt IEC's IP enclosure rating standards in place of the current NEMA?

    Adoption would need to come through installation codes such as the NEC. It is highly unlikely the IP rating system would replace the NEMA Type ratings. The IP system has no provision for addressing corrosion, exposure to oil and other enclosure construction features. The most likely scenario is a blending of the two systems where they coexist.

Watch the on-demand webinar and learn more about UL 508 to IEC/UL 61810-1 transition for electromechanical relays. Or learn more about our other services for related solid state or relay switches.

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