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Entry type: FAQ Entry ID: 14399444, Entry date: 05/03/2013

MICROMASTER 4 (MM4), SINAMICS G110x G120x: Description of UL and cUL Listing and Recognition.

  • Entry
  • Associated product(s)
This FAQ applies to the SINAMICS G110, G120 series and MICROMASTER 4 inverters.

What does UL and cUL listing mean, and why are some products UR recognised?


UL Listing

UL stands for Underwriters Laboratories, an independent US test organisation. UL Approval (or recognition or listing - see below) is often a requirement for equipment in use in the USA and other countries.

Listing, Approval and Recognition
UL listing is usually received either before or immediately following product launch.

  • The marking of the product is only allowed when the testing of a production unit is successfully completed and agreed with UL, hence there is often a delay with marking of a new product

Different products are tested in different ways

  • Siemens Drives are tested with reference to UL508C. This document also specifies the requirements for motor protection equipment, and most drives meet this requirement as well; see Operating instructions - Safety Instructions for further details.
  • Siemens Drives always submit their drives for UL testing, or carry out the testing under the control of UL.
  • UL have only recently begun to issue certificates.
    In the past, they have simply maintained a file which lists all the products that meet their standards



UL deals with products in different ways. Individual components are usually recognised and marked with the UR marking. Components that form part of a system, such as a drive are usually listed, and marked with the UL and cUL. Complete installations are approved. These different definitions are not important to the user. Most Standard Drives products are listed, but some COMBIMASTERs and some accessories are treated as components and therefore are recognised. All products carry the same file number.



In the past the Canadian Standards Authority (CSA) operated their own tests and standards. For products such as Siemens Drives it is now accepted that the UL tests generally meet their requirements. Therefore subject to some additional work, and of course, successful UL testing, the cUL marking can be added to the product. This is generally accepted in place of the old CSA mark.

Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit