A New US Standard for Safety Light Curtains – the OSHA Impact

Joe Lazzara, President & CEO, Scientific Technologies Inc.

U. S. based exporters of machine tool and factory automation equipment are, by now, used to complying with various international standards, such as those required by the CE mark. Now we are beginning to experience – albeit slowly – the adoption of voluntary U.S. standards based on ISO, IEC or EN norms. A recent example is ANSI/UL 61496-1&2 on Electro Sensitive Protection Equipment, ("ESPE"), which includes devices more commonly know as safety light curtains. ANSI and UL have announced this U.S. voluntary standard with an effective date of July 29, 2004. Although "new" for the US market, it is really based on IEC 61496 that has been published for several years. Let’s examine the potential impact of the US standard and how it may relate to OSHA regulations.

First, a history lesson. UL has offered testing services for safety light curtains under a listing identified as QUHP – Presence Sensing Devices Under Press and Other Power Machine Controls and Systems. The letters QUHP are merely an UL identifier – they are not an acronym. Essentially, a presence sensing device was tested as a machine control, under a variety of UL standards, but none specifically written for a safety light curtain. In fact, the standards were not technology specific; i.e., the "presence sensing device" could be optical, radio frequency or other methods.

More recently UL created a new listing category designated NIPF, titled "Active Optical Electronic Protective Devices". This is the international term for safety light curtains, although it can also include laser devices. Under this category, only optical technology products are tested. The ANSI/UL 61496 standard is based on IEC 61496, the international version, with minor changes to accommodate the requirements of the American Standards, UL 508 (safety - industrial control equipment), UL 840 (insulation coordination), NFPA 79 (electrical standard) and UL 796 (printed-wiring boards). UL would evaluate a product to these tests and standards.

UL has announced the light curtain products currently listed in UL category QUHP (the older category) will remain valid until July 29, 2004. After that date, safety light curtains will only be listed under the newer category, NIPF. Products listed under QUHP will either be reviewed and relisted under NIPF or these products will no longer be UL listed products. Of course, it is possible now to purchase light curtains that are listed under the newer NIPF designation. For example, STI has several models under NIPF, including our popular STI 4600 Series of safety light curtains.

There are many other standards in the United States that involve the design, construction, installation and use of safety light curtains. For example, ANSI B11.19, Safeguarding When Referenced by the Other B11 Machine Tool Safety Standards – Performance Criteria for the Design, Construction Care and Operation is a good example of a helpful standard for the safeguarding techniques and devices. Incidentally, a new version of B11.19 is due to be released during 2002. The recent robot standard, ANSI/RIA R15.06 - 1999 has design criteria and installation information on safety light curtains, especially when applied to robotic guarding applications. And if you enjoy reading IRS tax code style prose, then you can even find information in OSHA 29 CFR 1910.217. (Okay, even OSHA standards are more interesting reading than the tax code…!) The following questions and answers will help you in determining the impact of the new ANSI/UL 61496 -1&2. Incidentally, "1&2" refers to parts one and two of the standard, which is the complete standard at this time. Assume any reference in this article means the complete document.

Will OSHA enforce the ANSI/UL 61496 standard?

The answer is … well, not exactly. First, ANSI documents are voluntary consensus standards and are not written as laws and regulations. Second, in some cases ANSI and OSHA standards may conflict. For example, OSHA recently publicized a letter of interpretation on the subject of this ANSI/UL standard. In this letter, OSHA points out that ANSI/UL 61496 "…includes the use of ESPE as a machine reinitiation device. This could conflict with existing OSHA standards, such as, presence sensing device initiation (PSDI) of mechanical power presses (29 CFR 1910.217) and minor servicing activities as specified in the control of hazardous energy (lockout/tagout) 29 CFR 1910.147." OSHA also raised other issues with the ANSI/UL 61496, including concerns about the use of references to other standards that are not adopted by OSHA. OSHA does acknowledge that electrical devices must be third party approved and are deemed approved if listed and labeled by a nationally recognized testing laboratory. However, this requirement is derived from the compliance of electrical safety, such as fire and shock, from OSHA Subpart S.

Does OSHA enforce standards once they are approved by ANSI?

OSHA would only enforce an ANSI standard if incorporated in a specific OSHA regulation. For example, in OSHA 29 CFR 1910.215(b)(12) requires that abrasive wheel machinery guards must conform to the ANSI B7.1 standard. Here, the ANSI standard is actually part of the OSHA regulations.

Does complying with ANSI standards ensure conformance with OSHA?

Usually, but not in all cases. Where there is disagreement, the OSHA regulations would have precedence. On this topic, OSHA states, "However, if the ANS [American National Standard, as adopted by ANSI] are not part of specific OSHA standards, but compliance with the ANS provides equal or greater employee protection, then complying with the ANS while failing to comply with the specific OSHA regulations would be considered a de minimis violation." Remember, OSHA standards represent minimum standards for compliance with the law, and employers are welcome to develop new methods to maximize employee safety – just ensure these methods at least meet the OSHA requirements.

Does OSHA require compliance with ANSI/UL 61496?

In this author’s opinion, it is unlikely that OSHA would require light curtains meet this specific ANSI/UL 61496 standard and only this standard. As we have seen, there are a number of other standards that provide information on the design, construction, installation and use of ESPEs. OSHA has already stated that it has potential conflicts with portions of ANSI/UL 61496, such as the specific machinery on which the ESPE is installed, to ensure that existing OSHA standards are met. For example, a usage prescribed in ANSI/UL 61496 may not be allowed by OSHA statute, such as using an ESPE to initiate cycles of a mechanical power press.

Certainly there are advantages to selecting a safety light curtain that meets the ANSI/UL 61496 standard, such as the STI 4600 Series. The testing prescribed by this standard is likely more rigorous than earlier standards, thus the purchaser has comfort that the product is tested to the most up to date requirements. The product selected would likely also meet the international IEC 61496, and for the OEM, means the product could be used on their machines globally. In addition, the ANSI/UL 61496 would be one way to meet the OSHA requirements for third party electrical safety approval by a nationally recognized testing laboratory.

Ultimately, it is most important for the employer to ensure that the installation and use of the ESPE selected is in accordance with the requirements of the ESPE and machine manufacturers, standards for the specific machine and OSHA regulations.

Be safe out there!

” Occupational Hazards Magazine, a Penton Publication. Reprinted with Permission."

Joseph J. Lazzara is President and CEO of Scientific Technologies, Inc ("STI"), the largest provider of automation safeguarding solutions in North America (www.sti.com).

Joe began his career with Hewlett Packard in 1973 where he had responsibility for safety and environmental issues for one of HP's largest divisions. After several other positions at HP in environmental, process and engineering management, Lazzara joined Scientific Technologies, Inc. (STI) in 1981 as Vice President and became President in 1989 and then
President and CEO in 1993.

He has a Bachelor of Environmental Engineering degree from Purdue University and a Masters in Business Administration degree from Santa Clara University.

Joe is the Chairman of the Safety, Health and Environmental Committee for the Association of Manufacturing Technology (AMT). He is also a member of the Board of Directors of the American Electronics Association (AEA), the nation's largest high-tech trade association.