Understanding ‘U’ and ‘X’ Certification

A common question we get asked (or must deal with) relates to the topic of “X” and “U” certification – what does it mean, how does it impact me and my supply & what do you need to be aware of?

Firstly, let’s look at how 60079-0 defines equipment and components:

3.25 equipment (for explosive atmospheres)

general term including apparatus, fittings, devices, components, and the like used as a part of, or in connection with, an electrical installation in an explosive atmosphere

3.8.2 Equipment Certificate

A certificate prepared for equipment other than an Ex Component. Such equipment may include Ex components, but additional evaluation is always required as part of their incorporation into equipment.

3.53 symbol “X”

symbol used to denote specific conditions of use NOTE The symbol “X” is used to provide a means of identifying that essential information for the installation, use, and maintenance of the equipment is contained within the certificate.

Now the definition of component per 60079-0 General Requirements:

3.28 Ex Component

part of electrical equipment or a module, marked with the symbol “U”, which is not intended to be used alone and requires additional consideration when incorporated into electrical equipment or systems for use in explosive atmospheres

3.8.1 Ex Component Certificate

A certificate prepared for an Ex Component. 3.52 symbol “U” symbol used to denote an Ex Component NOTE The symbol “U” is used to identify that the equipment is incomplete and is not suitable for installation without further evaluation.

So, what does this mean in summary? The most important fact is this: To install any electrical equipment in the field (hazardous area), it has to have a device certification! It is strictly forbidden to install equipment which only has a component certification. ATEX components are certain parts such as enclosures, barriers, or glands, etc. that are pre-certified by the manufacturer. These parts, including their component certification, allow a device manufacturer/end user to utilise them as parts of their products and also to get the final ATEX-device certification for the produced goods.

For example, a device-manufacturer may buy component-certified barriers to use them within their products and to get the certification of the entire device. Nevertheless, they would not simply be allowed to just assemble them: After the evaluation of all technical values and the execution of all necessary tests, a notified body still has to check the manufactured device to finally confirm the EC-Type Examination and to make sure that everything is within the standard.

A common misconception is that a user can purchase a “U” component certified Exd enclosure, for example, fit whatever equipment they choose inside, and be good to go. However, this complete “assemble” would require verification from a 3rd party before being safely installed.

So to summarize some key points here:

• ‘U’ certified products are components and not assemblies. Per 60079-14, equipment that is considered to be an assembly must have an assembly certification and cannot be put into use as a component certified piece of equipment without further evaluation/testing.

• ‘X’ certified products have a condition for safe use. These can be used safely in hazardous locations but the specific conditions must be followed in order to be safely used.

JCL can help you navigate your way through your certification requirements, working with a network of manufacturers, notified bodies and industry experts, we will ensure your project is delivered in line with local standards & in a timely, cost-effective manner.