TYPES OF APPROVAL Before you complete the design of your product in accordance with the standard's requirements, you have to decide what 'proof' you need to show that it complies. This is not
a purely technical decision, but requires marketing, legal and technical input. Your decision depends on questions such as:
- In what countries do you want to sell the product, now and in the future?
- What are the national deviations for IEC 60950 in the countries where you will sell the product?
- Is compliance mandatory in the target market?
- If not mandatory, would it be advisable for product liability reasons?
- If not mandatory, would it be advisable for marketing reasons?
- If mandatory, is approval by a specific test house required?
- Can compliance be shown on the basis of self-declaration?
- What material is needed to justify self-declaration.?
There are two types of approval you can get from a test house. Which you choose will depend on the answers to the questions above. 1. The test house will test the product, and if compliant,
will give you a license to put their 'mark' on each item of the product you ship. This generally involves paying an annual license fee, as well as periodic visits to your
production facilities to ensure that the product you are selling is identical to the product tested. 2. The test house will test the product sample or samples
you submit, and if compliant, will issue you a certificate and test report with regard to the compliance of those samples only. As long as the product you sell is identical
to the sample tested you can use the certificate and test report as justification for self-certification in situations where this is acceptable, e.g. for the Low Voltage
Directive in the European Union. If you alter the product, you should refer back to the test house to see if any additional testing is necessary and any changes need to be made to the test report.
WHAT YOU NEED TO PREPARE
In addition to one or more samples for testing, you will be asked to submit the following material to the test house:1. Product Schematics 2. Assembly Drawings 3. Parts List 4. Users Manual 5. Installation Guide 6. Data sheets and approval certificates of safety critical components. 7. Where circuits which must be separated are on a
printed circuit board, a copy of the PCB layout transparency, marking the separate circuits.
Safety critical components are those components which can affect safety. This include all components in primary circuitry (e.g. power supplies, transformers, mains switches, etc.) and any other component, the failure of
which can affect safety (e.g. optocouplers, thermal switches, lithium battery circuitry, etc.)The test house will need to see the approval licenses for
safety critical components in order to ensure that they were approved to an appropriate standard, and that they are used in accordance with any conditions specified in
the approval license. It is to your advantage to use components that have been approved by the component manufacturer, otherwise you will have to bear the cost of approving the component, as well as ensuring that the
manufacturer does not change the component specification. The manufacturer and model number of safety critical components will be recorded in the test report. It is also
advantageous to have second sources of safety critical components recorded at the time at the testing. It will probably cost more to have them included at a later stage.
Many product approvals are delayed due to difficulties in getting copies of component approval licenses. You should ask for these certificates at the time you decide
to incorporate the component in the design. Do not wait until you submit the product to the test house.
COURSE OF A PRODUCT INVESTIGATION 1. The test house should send you a checklist of the
material they need for the investigation, similar to the checklist above.2. The engineer in charge of the investigation will carry out a constructional review of the product, checking that
it complies with the constructional requirements of the standard. If there are any non-conformities you will be sent a deviation letter, listing the problems and asking for your response. Depending on the problems, the
response may be a declaration that changes will be made (e.g. to documentation or markings), or may involve alteration of the product design and resubmittal.
3. Once the issues in the first deviation letter are resolved, the product will be tested in accordance with the tests that the engineer considers relevant to your product. Once again, if there are any non-conformities
you will be sent a deviation letter, and a response and possible changes to the product are required to resolve the problems. 4. Laboratories which are accredited to ISO Guide 25 or
EN 45001 are committed to allow you to witness your product's testing, if you wish. You should question the engineers findings if you have doubts about the results. The standard cannot cover all situations, and the
engineer sometimes has to interpret the standard's requirements for your particular product. You certainly know your product better than the engineer and if you take the trouble to learn the relevant parts of the
standard, your interpretation may be different, and if reasonable, you may be able to persuade the engineer or his reviewer that your interpretation is acceptable. A well argued response, based on the standard and sound
engineering judgment, may prevent the need for product changes. 5. Once all issues are resolved, and the engineer has all the documentation he needs, he will complete the test
report and certificate. Check all the details on the certificate and test report for mistakes. They should include the name and address of the manufacturer, the product name and model, the serial number of the item
tested, and the standard to which the product was tested, including any amendments to the standard and their dates. 6. It is good practice to have a person responsible for
reviewing any changes to your product from the point of view of compliance. This person should sign off every change to the product. He should liaise with your test
house to see whether retesting is necessary or a change is required to the test report. If you are subject to factory visits, the inspector has the right to revoke your license
to 'mark' the product if it differs from the product tested. A particular source of problems is the substitution of safety critical components. Your test report specifies the
manufacturer and model number of such components, and your license becomes invalid if you substitute a second source. You should try to plan second sourcing in advance and have alternate components included in the
initial testing of your product. 7. From time to time standards are amended, and older versions of the standard may no longer be in effect. In this case your approval may need to be updated to the
newer standard. Depending on the nature of the standard amendment and your product, this may involve no testing, partial testing, or even product redesign.
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