designing for product safety

Thinking about regulatory compliance early in your design can help to save time and money later in the process.

Manufacturers were once free to market almost anything with little legislation, resulting in injuries or sometimes fatalities. Nowadays, if you are a manufacturer or importer of goods, you must ensure they are safe for the consumer to use by complying with the appropriate standards. A safe product is one that presents no risk, or minimum acceptable level of risk, when used as intended.

Unfortunately, it is not uncommon for a product to be designed without research into the appropriate standard, which can present regulatory compliance issues and therefore costly delays whilst revisions are made. It is vital that a product is designed with knowledge of the specific electrical safety standards that need to be applied in order to decrease the chances of there being issues at the regulatory approval stage. In this article we talk briefly about product safety testing, what the key terms are and at what stage our team can help.

What are the electrical product safety regulations?

In Europe, the Low Voltage Directive (LVD) (2014/35/EU) exists to ensure electrical equipment within certain voltage limits does not present risk to the user. The LVD covers health and safety risks on electrical equipment operating with an input or output voltage of between 50 and 1000 V for alternating current, 75 and 1500 V for direct current.

In the UK, manufacturers must comply with the Electrical Equipment (Safety) Regulations 2016.

How do I design a safe product?

We appreciate that product design is complex, but the sooner we are involved the smoother the process of safety testing is likely to be. Unfortunately, we often see products that have been designed with little or no regard for EMC and Safety requirements, which then need an expensive ‘fix’ later in the process following undesired test results. Safety standards are often long and complex, so even if they have been reviewed at the design stage, it may be misinterpreted.

Our team can get involved at the design or prototype stage, where we offer a pre-compliance testing service, which allows us to identify any potential product safety issues early in the process and amendments can be made at a point where it is often easier and more cost-effective. We use the same test equipment and procedures for pre-compliance as we do for full-compliance testing, so you are guaranteed consistency.

There are many elements to safety standards, and our engineers will review your documentation, complete a physical inspection and carry out dynamic tests whilst completing a safety assessment. It is therefore advisable that manufacturers have an understanding of what will be carried out during testing, which will include:

-thermal tests to check components do not exceed the limits allowed and can function with the heat generated by a device.

-single fault tests. These are applied one at a time to check that the product does not become unsafe

-high voltage tests, where we will check that breakdown does not occur

-input current check to make sure that the ratings marked on the equipment are not exceeded

-touch current measurements to check the current that would flow through to a person if they were to touch the appliance

-insulation resistance checks

-mechanical strength tests

Product documents are included in the safety assessment

It is important to note that the markings and documents form part of a safety assessment, and so must be given the same attention as the product itself. Engineers will also review your documents, including the user and installation instructions and how easy they are to understand, as part of the safety assessment. In our experience, insufficient technical documentation or product documents are often the cause of compliance failures. The product must also have the appropriate safety warnings, in the correct location, and the manufacturer’s details.

Where will the product be sold?

A designer needs to know which country a product will be sold within, as the standard requirements defer according to the market and may therefore affect the design. For example, voltage ratings and wiring methods may vary by continent.

Different countries also have different safety-related marks. The CE mark in Europe and UKCA in Great Britain, are self-certification methods, whereby manufacturers can evaluate a product themselves but this can be a high-risk strategy, so a test house is often used to evaluate the product. Safety marking in the USA and Canada consists of a few options, with certifiers being accredited as a Nationally Recognised Test Lab (NRTL) and by the Standards Council of Canada (SCC). For the rest of the world, manufacturers can look to get their product CB tested, which is an internationally recognised scheme aimed at making test requirements more straightforward across over 50 countries.

As well as the country that it will be sold in, it is important to consider the environment in which the product will be situated as this may impact the materials that are used and the tests that are needed. For example, a designer will need to know whether a product is likely to be exposed to humidity, dust or water.

Consider the enclosure

The enclosure is also of great importance, as it has to be functional and be able to pass the relevant safety standard. For example, if using a plastic enclosure, a manufacturer must consider the flammability rating and this often varies depending on the thickness of the plastic. Enclosures may need be able to withstand impact, heat, exposure to UV, to name a few. Openings in the enclosure must not present a safety hazard to the user, such as shock or fire.

PCB design

It goes without saying that good PCB design is vital, and ensuring the layout is correct can help to mitigate against other issues, such as creepage and clearance. Standards detail the minimum amount of creepage and clearance allowed and this is important to ensure conductors cannot arc to one another and cause a safety issue.

EMC Testing

An EMC failure may result in changes to components, which in turn may have an effect on safety testing. It is therefore advisable that EMC is carried out first.

Medical device requirements

As you would expect, medical devices are heavily regulated and therefore there are additional safety requirements and complex standards that are tested against. Although compliance with ISO 14971 is not mandatory, many customers will look for it as a sign of commitment to safety and the risk management process. One of the main issues we see is that manufacturers can underestimate the length of time required to construct a suitable risk assessment, which should be created throughout the design stage to mitigate identified hazards. The risk assessment will be evaluated as part of the documentation review, which will take place ahead of testing.

What do I need to provide for testing?

- Working samples, including any accessories that are sold with the product. We usually require 3 samples and the testing may mean that the product cannot be returned in working condition. If the product case is likely to be damaged when opened, we will also require an open sample.

- User manual and installation instructions. These are reviewed as part of the assessment

- Circuit diagram

- Approval documentation for any safety-critical components

- If applicable, representative load

- AC cables applicable for the countries that will be included in the assessment

- Certificates for flammable materials that are critical to safety, e.g plastic flame enclosures, PCBs

- Samples of components that are intended to rupture during fault tests, e.g fuses

If critical components are unknown, we identify these as part of the assessment.

How much does electrical product testing cost?

At Cranage EMC and Safety, we take the time to review each project and the testing requirements on an individual basis and therefore it is not possible to advertise costs. Our engineers have years of experience across many industry sectors, so please get in touch to discuss your testing requirements and we will be happy to help you.