A safety critical component is a component of a system which is relied upon for safe operation. Generally speaking, components in the primary AC circuit (where mains power enters the equipment), bridging insulation between primary and secondary circuits, between the primary circuit and the user or patient, fans, batteries, battery protection circuits, thermal regulators, fuses, and interlocks are considered safety critical.
Most components deemed to be safety critical must be Listed or Recognized by a Nationally Recognized Testing Lab (NRTL) to an applicable component standard. The implementation of the component, within the product, is also evaluated to make certain it meets both the Conditions of Acceptability (CoA) of the component and the requirements of the end product standard. The utilization of Listed/Recognized safety critical components in compliance with the CoA’s and the requirements of the end product standard enables PTI to perform a minimal evaluation of the safety critical component. In rare cases, safety critical components which are not Listed/Recognized may be used; however, in these cases the initial cost of the evaluation is increased and the additional cost of annual retesting of such components will be incurred.
When PTI encounters an unrecognized critical component, usually during a construction review, we will inform you in our initial findings report and discuss your options and the desired path to compliance with you.
This link will direct you to a list of US NRTL marks to look for when selecting a safety critical component: http://www.osha.gov/dts/otpca/nrtl/nrtlmrk.html
Wade Munsch is a Product Safety Engineer for Professional Testing (EMI), Inc. Wade holds a Bachelor’s Degree in Electrical Engineering from The University of Texas at San Antonio. Wade offers expertise to clients in several product safety standards including Information Technology Equipment, Laboratory, Measurement, and Control, and Medical Safety standards.
