NEMA LS 1: Low Voltage Surge Protective Devices

Rescinded 2009

History of NEMA LS 1

The NEMA standard LS 1 was published in 1992. The document provided manufacturers and specifiers with guidelines to describe and compare low-voltage (less than 1000V RMS) Surge Protective Devices (SPDs) using a uniform terminology and format. The document was reaffirmed in 2000 without modification to the 1992 document and was later rescinded in 2009. 

LS1 provided guidelines only. It did not introduce new standards or test methodology, nor did it define extensive vocabulary for SPDs. IEEE C62.41-1991, C62.45-1987 and ANSI/UL 1449-1985 were referenced documents in LS 1. These referenced documents gave a comprehensive description of the surge environment, waveforms, testing and applicable safety standards for surge protective devices at that time.

NEMA LS 1 was rescinded in 2009 because the document was determined to be out of date and many industry standards related to the surge environment and surge suppression had been significantly updated since the original LS 1 standard was published in 1992. In addition, knowledge regarding the surge environment has increased since 1992 and a number of new standards related to surge suppression had been published.

What to Use in Place of NEMA LS 1:

There are no plans to revise or republish the NEMA LS 1 standard; however, NEMA is always open to industry feedback regarding the value of a similar document or other material that can support the electrical industry with accurate information and guidance on surge protection.

For more information about the surge environment, test methodology and application considerations, refer to:

·         IEEE C62.41.1
·         IEEE C62.41.2
·         IEEE C62.45
·         IEEE C62.62
·         IEEE C62.72

For more information about the safety standard for surge protective devices, please refer to ANSI/UL 1449-2006 (3rd Edition).

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