Choosing Suitable Components

How we can help?

We at RN Electronics can provide the necessary test and consultation services to help you select appropriate components.

Choosing appropriate components at the design stage helps reduce costs and meet the requirements of harmonised standards under the low voltage directive. The questions below will help in understanding which components are critical and how to choose appropriate type.

What are safety critical components?

Safety critical components are but not limited to – Power supplies, transformers, X-caps, Y-Caps, resistors bridging insulation, optocouplers, surge suppression devices, line filters, line switches, mains inlets/ outlets, fuses, thermal cut-outs, safety interlocks, mains lead etc.

These are components, the failure of which will result in a hazard.

What do we mean by an approved component?

Approved components are those components that have independently evaluated to comply with the requirements of a relevant standard by a recognised third party test laboratory (an accredited body of some form).

Why do safety critical components need to be approved?

Use of an approved component ensures that component performs its required function reliably. Use of a pre-approved component helps in ensuring the compliance of your product. It also means less work at testing stage. For certain third party assessments / certifications use of pre-approved components is an absolute must. If components are not approved then that may substantially increase the test time and therefore the cost of your overall product.

How to ensure safety critical components are approved?

Generally components carrying some form of third party certification marks are acceptable. For example: VDE, ENEC, TUV, FI etc. These components will carry some form of reference to test certificate or test report. However, it is advised to obtain copy of test certificate and report for your technical file. This approval information must be reviewed to ensure that the parameters of approval are suitable for your application.

Care should also be taken to ensure that component is approved to appropriate standard.

Are CE marked components acceptable?

All products sold in the EU have to be CE marked. CE mark is not a safety certification mark. CE mark covers a full range of directives for example EMC directive, R&TTE directive etc. Thus by looking at CE mark alone it is not possible to say which directive it covers or if some form of safety assessment has been carried out on the component.

A CE marked component may be acceptable if technical file shows that product complies with a relevant harmonised standard under the Low Voltage Directive. This decision can’t be based on looking at declaration of conformity alone; some form of a test report should to be reviewed.

UL, CSA approved components, are they acceptable?

For product intended to be sold in EU the simple answer to the question above is – no. Some UL and CSA standards are harmonised with European requirements. In such a case there are no issues. However in other cases UL and CSA approval bares no relevance for European approval as operating conditions during test are different, test levels and hazard levels may be different. This applies the other way round as well. For components intended to be sold in North America, the European approval is not relevant, unless there is harmonisation between UL and European standard.

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