William D. Webb

Coordinating R&D, manufacturing, purchasing, distribution, quality control, and field service is necessary for a successful safety-mark effort.

The main reason for getting a product safety-agency mark—UL, CSA, TÜV, etc.—is to show that the marked product is safe for use in its intended application. This certification or listing is based on the manufacturer having an accurate and up-to-date agency report. This article discusses the dual processes of creating and maintaining a safety-agency report.

Because it is responsible for the most common and most recognized mark in North America, Underwriters Laboratories (UL) is the only agency referred to in this article. The agency-report process is essentially the same for any safety mark. However, report formats do differ, and some agencies rely heavily on ISO 9000 quality systems. In these cases, audits may be performed only once a year and focus on the manufacturer's quality system, whereas UL still relies on quarterly audits.

The Agency Report

The agency report serves two purposes. First, its creation earns the product the UL mark. Second, its maintenance enables the product to keep the UL mark. The safety-approval process is based on the assumption that a product's component information as presented in the agency report precisely matches the data for components actually used in the product. This is how UL protects its interests and maintains its responsibility as a product-safety authority.

To create the agency report, UL engineers use photographs of relevant assemblies, along with an item-numbering system to reference each component. Each item is then detailed in the body of the report. The basic process for creating a UL report is shown in Figure 1.

The basic rules for writing a report are not unlike the basic rules for writing an ISO 9000 quality-system procedure. ISO 9000 is a documentation scheme that provides written procedures for all aspects of the product development and manufacturing processes. The ISO slogan is, "Say what you do and do what you say." In other words, document what you actually do, and then do what you wrote down. This may sound simple, but too often the interpretation is, "Say what you think they want to hear." And in practice the engineer says, "I can't do that—it's too much trouble." In the case of safety approvals, the manufacturer must remember that the auditor has been trained to go by the book. This leaves very little room for interpretation. Some auditors will be accommodating, but the manufacturer should not count on it.

Agency-Report Maintenance

UL field representatives generally hold audits on a quarterly basis. In instances of discrepancies between the product and the report, representatives almost always issue a variation notice (VN). For instance, if the report specifies an opto-coupler, perhaps a GE P/N 20052, but a GE P/N 14053 is what shows up in the product, the auditor will flag it as a problem—even if the part is a functional substitute. This is an important point, because the accuracy of the safety testing is based on the equipment under test (EUT) essentially representing a production unit. The tests—mostly electrical, mechanical, or fire safety—are performed on the EUT with a given set of components and assemblies under controlled and repeatable conditions. If a component or assembly listed in the report is changed by the manufacturer without notifying UL, a test or an entire suite of tests previously performed by UL may become invalid. This may sound harsh, but UL becomes responsible as soon as its name is placed on a product. The basic process for maintaining a UL report is shown in Figure 2.

The severity of the action taken by UL is based on the component in question and its place in the product's safety scheme. For example, the use of a wrong opto-coupler could result in a 15-day alternate-component justification, whereas the use of a wrong power supply could result in the shutdown of production lines until the discrepancy is resolved or the UL label is removed from suspect products, including products already shipped. Whether the manufacturer decides to field-repair the product to comply with the requirements or remove the UL label, implementation and coordination of such a task can become a logistical nightmare.

Methods for Avoiding VNs. Make sure the report is accurate. Keep the report up to date with all design changes of components covered in the report. Communicate any changes or updates to UL before they are implemented. Build a relationship with UL based on trust. Ask questions and get complete explanations for parts of the report that are confusing or controversial.

These concepts are simple but can take a considerable and ongoing effort. They require coordination and commitment from all of a manufacturer's resources—including management. If management does not support the effort 100%, it is doomed to failure.

Actions Certain to Encourage VNs. Make changes to the report without UL's knowledge or approval. (Manufacturers should always communicate changes to UL.) Cover up a discrepancy. (This amounts to burying a land mine to be stepped on later.) Get into a heated debate with a UL representative about personal opinion. (Stick with the facts and follow the standard. Don't be afraid to ask for an explanation if a standard is open to interpretation. UL also has program leaders who mediate between manufacturers and UL representatives when an impasse is reached.)

Additional Tips. Work with safety-agency engineers to create and review reports that will work for, instead of against the manufacturer. Stay involved: The manufacturer cannot provide what is expected if it does not know what is expected. Keep in mind that quarterly audits from UL can turn into a series of brushfires that must be addressed to keep product lines moving.

Keep the report as simple as possible. If an item is in the report, it will be audited, so make sure the item belongs there. If a component has a short life cycle because of obsolescence or technological evolution, keep the description as generic as possible. For example, hard-drive memories grow as computers evolve. A product design may not change for five years, but during that time its hard-drive memory can increase four or five times. Choose a drive that is recognized or listed. Rather than specifying a memory size, list only a range or minimum size. Use the phrase "or equivalent" whenever possible. Again, work with the UL engineer to define a solution that works for, not against, the manufacturer and the manufacturer's product.

Standards

Hundreds of product-safety standards are used in both North America and the European Union. Some of the more common safety standards include EN 60950 and UL 1950 for information technology equipment and CSA C22.2, EN 61010-10, UL 1262, UL 3101-1, and UL 3101-2-20 for laboratory equipment.

Conclusion

Agency and compliance personnel must coordinate the safety-mark effort, but R&D, manufacturing, purchasing, distribution, quality control, and field service must all work as a team for the effort to be successful. The R&D group needs to design products using listed or recognized components or subassemblies whenever possible. When it is not possible, the component must be flagged and evaluated by compliance and agency personnel. When the manufacturing engineers get involved (the sooner the better), components can and do get changed or substituted. Tracking these changes is critical to the accuracy and maintenance of the report, which is why ISO 9000 accreditation plays a key role for obtaining any safety mark. Manufacturers that have a quality system in place will save both time and money.

William D. Webb is a senior compliance engineer at Dictaphone Recording Systems Group (Stratford, CT). He has three decades of experience in R&D and compliance—EMC, safety, and telecom—between Dictaphone and E. I. DuPont Medical Products. He can be reached at compliancehelp@yahoo.com.

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