UL 60384-14 is the North American adoption of the international sectional specification for fixed capacitors used for electromagnetic interference suppression and for connection to the supply mains, and it is the document under which such components are recognised in the United States and Canada. The certificate matters commercially as much as technically, because these capacitors are safety critical components: a short circuit in a capacitor placed across the line, or a breakdown in one connected between line and earth, can start a fire or expose a user to mains potential. A designer building a product for the North American market will therefore normally be required to use a component that carries a recognised component mark to this standard, and the substitution of an equivalent component from an unapproved source invalidates the product certification. The standard defines the X and Y classifications, the ratings and the test programme, including voltage proof, endurance and active flammability.