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Top 10 Frequently Asked Questions About UL 508C to UL 61800-5-1 for Motor Drives

The safety Standard used for adjustable speed electrical power drive systems has changed from UL 508C to UL 61800-5-1. Here are the top 10 frequently asked questions about the transition.

electrical drive controller application in industry plant

April 24, 2020

On Feb. 1, 2020, the safety Standard used for adjustable speed electrical power drive systems changed from UL 508C, the Standard for Power Conversion Equipment, to UL 61800-5-1, the Standard for Adjustable Speed Electrical Power Drive Systems. Watch our webinar to learn what this transition means for your motor drives covered under UL 508C. And then below, check out the top 10 frequently asked questions about the transition.

  1. If I open a single project to evaluate for U.S., CE and CB requirements, will I save effort and money over separate projects?

    UL has already compared requirements between the U.S., IEC/EN and CSA standards to determine a single investigation and test plan to certify your product to all three standards. Conducting a single investigation instead of three investigations can help save significant time and cost.

  2. How will I know if a change to my UL 508C product will require the product certification to be done to UL 61800-5-1?

    A change to your product that is safety critical, referred to as an alternate construction, will require the product certification to be updated to UL 61800-5-1. Note that an equivalent component replacement is not considered as an alternate construction, and thus does not require the product certification to be updated to UL 61800-5-1. Please contact your UL certification engineer if you need to verify whether any changes you make will require certification to UL 61800-5-1.
  3. If I have a product evaluated to UL 508C and I need to add an alternate component, can I use UL 508C?

    If the component is an equivalent component replacement, yes. If you are unsure of what an equivalent component is, please contact UL.
  4. If I test to UL 61800-5-1 and test to the differences from the IEC 61800-5-1 standard, am I compliant to IEC61800-5-1?

    You would be in compliance with the technical requirements of the standard. However, IEC compliance generally also requires the IEC Test Report Form for proof of compliance.
  5. Since UL 508C is being withdrawn, how is UL addressing other current UL Standards that only call out a UL 508C Listed product as acceptable for use?

    Proposals are being made to update Standards that reference UL 508C. These proposals will be handled by the technical committees for the affected Standards.
  6. Can I have an evaluation done to CSA standards through UL?

    UL can provide certification for Canada (C-UL or C-RU) using the CSA C22.2 No. 274 standard. 
  1. Does UL 61800-5-1 apply to bypass circuits and drives?

    In some cases, drives are designed with bypass circuits incorporating contactors and overload relays. If a bypass circuit is an integral part of a drive, it will be part of the UL 61800-5-1 certification of the drive. The components of the bypass such as contactor and overload relay will have to comply with their appropriate component Standards and be used within their ratings.
  2. Is an evaluation to UL 61800-5-1 applicable for the exciter of synchronous motors?

    A motor exciter can be investigated to UL 61800-5-1.
  3. Is the breakdown of the components test required at standard fault and at high fault current?       

    Both standard fault and high fault tests must be considered. If it can be shown that the results of the test at high fault will be the same as standard fault, then the test only at standard fault is required.

  4. How can I get the motor drives Spacings Tool?

    More information about the Spacings Tool for adjustable speed drives can be found at A subscription can be purchased quarterly or yearly for access to the tool. Additionally, you can request a quote or a demo.

Watch our on-demand webinar for more information about this transition and to learn how you can simultaneously expand your product's marketability while reducing product development time and cost.

Virtual Workshop: UL’s Transition from UL 508C to UL 61800-5-1

Spacings Tool Subscriptions- 3 Months or 1 Year

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