As you can probably guess, safety testing is all about making sure a product is unlikely to cause harm to it’s environment, users, installers and/or others. Let’s use our example from previous articles, a hand-held product which measures sound pressure. We need to apply a safety standard to our product due to the Low Voltage Directive (LvD) which refers to voltages typically below 1000v.

Most safety standards explore the product in normal working conditions, and single fault conditions within the product. Over-temperature, over-voltage, over-current, fire and water ingress are considered in most standards.

In electronics, there are a few standards that crop up repeatedly:

EN 61010-1: Safety requirements for electrical equipment for measurement, control and laboratory use. Useful For: Equipment which measures a physical property and records or processes it in some way.

EN 62368-1: Audio/video, information and communication technology equipment – Part 1: Safety requirements. Useful for: AV equipment, things which connect to a PC in some way.

EN 60335-1: Household and similar electrical appliances. Safety. Useful for: This is a huge standard and includes dishwashers through to cattle fence energisers. If a product could be used in a home, this could apply.

EN 60730-1: Automatic electrical controls. General requirements. Useful for: Useful for measure and control systems, like central heating controls.

One of the advantages behind the standards listed above is that they are harmonised standards. This means they are recognised in many territories which could be useful if your product is going to be sold outside of the UK and Europe.

What happens at the test house?

When you present your product for test, the test engineer will create a form which mirrors the clauses from the standard. They will then complete the form, clause by clause, testing the clauses that apply. For example, if your enclosure has a cooling grille[MC1] they will check the slots with several test fingers to make sure it meets the requirements. As we said above, the consideration is normal operation and single fault conditions.

One of the most important aspects of safety test is the data for any components which form a safety protection – these are known as safety critical components. These may be:

• Connectors
• Internal wiring
• PCB material
• Fuses and fuse holders

When the product is put forward for testing, the details of these parts must be presented, along with:

• Schematics (system and PCB’s)
• PCB layout
• Mechanical drawings (including tolerances)
• The user manual and installation manual (if applicable)
• All warning labels and other equipment labels (such as the rating labels)

It’s important to remember that in most standards the legibility of the labels is tested, so these need to be correctly manufactured, not just paper labels.

Safety testing can take a long time. Most standards require the device to be preconditioned in some way, often for 96 hours. Temperature measurements are taken until the temperature stabilises, which could take 24 hours or more. Even for a modest product, the process could take as long as 4 weeks, so ensure you have allowed enough time.

What happens if my product fails?

It is unusual for a product to completely fail but there may be some aspects which require attention. This could be as simple as insufficient creepage allowance on PCB tracks. In this case, the PCB can be updated, fitted to the unit, and just the aspect which has failed retested – just like an MOT on a car. These retests are not included in the test house fees, so you will probably incur additional charges. Most test houses request two samples be presented so that if one test fails, they can continue with the second unit.

So, where does Cubik EPS fit in?

Cubik EPS has been through this process many times with many products. As well as our in-house pre-compliance test capabilities, which can de-risk this process, we can help with the production of the documentation that must be presented with the device for test. We have the experience to assist with debug of failures and may be able to suggest simple fixes which can be implemented.

Our experience in this area often speeds up the duration of the process, especially when other territories (and therefore other marks) are needed, for example USA, Canada, Australia, Japan etc.

Safety take-away:

Safety critical components, enclosures and single point failure modes are all critical. As soon as you have confirmed the standard which you will apply, get a copy (ensure it’s the latest) and work out what will be needed. The route to success is to design a product to meet the standard. Just pushing a product through test, will likely result in a fail.