This Compliance Today blog post explores the meaning of what is known in product safety certification as Conditions of Acceptability.
Conditions of acceptability only apply to recognized components, not listed components.
Listed components are complete in construction and can be used without further design concerns. This means that during the certification of the component itself, the agency was able to either simulate the worst-case application (therefore covering all possible applications) or determine that the performance of that component regarding safety is independent of the end-application. For example, a listed power supply will always have the same I/O ratings and safety isolation, regardless of how it is employed.
Recognized components, on the other hand, are incomplete in construction and further consideration must be given to the design employing that component. Unlike a listing, during the certification of this component, the agency was not able to simulate worst-case application or determine all possible applications.
Therefore a set of application conditions must be generated in order to complete the design or ensure performance with regards to safety is not jeopardized when the component is placed into service in an end product. These are known as Conditions of Acceptability (aka CofAs) for that recognized component.
For example, a recognized power supply will likely be for assembly into an end-product. It will likely lack an enclosure. A condition on the use of this component would be to ensure a suitable enclosure is provided when employed in the end-product.
Recognized components have conditions of acceptability detailed in their certification report. This report can be obtained from the component manufacturer. The CofAs are required to be addressed by the agency during the end-product investigation same as any other requirement from the standard.
CofAs are typically required for the following components:
- Power supplies
- Overcurrent, overvoltage and overtemperature devices
- Switches, if endurance or reliability is critical
- Any other safety isolating components
It is incumbent on the client to obtain the CofAs where they are required for the project. The client is in a better position than the testing agency to obtain these documents as the client is the buyer of the component. This usually gives the vendor of the component incentive to make these documents available upon request. In most cases the CofAs can be supplied directly from the vendor and in some cases the manufacture may provide them.