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CompEx: What is it and why do you need to know about it?

Are you working in a potentially hazardous or explosive environment? You may think your workplace doesn’t require special attention, but a surprising number do, and many companies are unaware of this.

AES is now qualified to work in such environments under its CompEx accreditation. It’s a landmark moment in the company’s history and development. But what does it mean for our customers?

In our special guide to CompEx, we explain what it is, and how AES’s certification might benefit your company.

What is CompEx?

CompEx is a recognised worldwide training and assessment scheme for ensuring that those working in hazardous or explosive environments, whether on land or offshore, are fully trained and protected.

It covers both employees of companies operating in these sectors and contractors – such as AES – who are charged with carrying out work at their premises.

The name CompEx refers to Competency working in Explosive environments.

Why is it important?

Firstly – and most importantly – it protects staff and contractors working in hazardous environments. Secondly, it helps to protect a company’s assets, such as buildings and equipment. Finally, businesses operating in these fields can often benefit from lower insurance costs as a result.

Which industries require protection?

Some workplaces are clearly hazardous, such as:

Others may be less obvious, such as petrol stations, distilleries or saw mills. In 2015, a wood treatment company in the Midlands suffered a devastating series of explosions in which four people died. It was reported that flammable materials kept on site included heating oil and kerosene, but also wood flour, which is used for laminate flooring and is highly combustible.

Why has AES decided to invest in CompEx certification?

Not all electrical engineers are CompEx certified – it’s a challenging test – so what led to AES choosing to go down this path?

Firstly, it’s important to have this certification if AES staff are to work in potentially hazardous or explosive environments. AES has a duty of care to its staff and safety is always a primary concern.

Secondly, putting employees through the CompEx course is seen as an investment in both the staff and the company, helping staff with CPD and allowing AES to work in sectors that it might otherwise not be able to go into.

What are the minimum requirements for those taking the CompEx course?

Candidates are expected to be already experienced in areas such as testing and carrying out inspections on electrical installations and to hold the relevant NVQ Level 3 qualification.

What are the elements of the course?

CompEx’s description of the course is as follows:

“The course will develop the delegates competency in the selection, installation, inspection and maintenance of electrical apparatus in potentially explosive atmospheres.”

The training part of the course lasts for five days. This is followed by two days of assessment, comprising practical and theoretical tests.

There are 14 “knowledge and assessment” units, which are usually taken in pairs. For AES, the relevant pairs are EX12A and EX12B, which relate to design and project engineers working on electrical installations that are suitable for explosive working environments.

How long does the accreditation last for?

Five years – after this time candidates are required to complete a refresher course.

Who is behind the accreditation?

The training scheme is operated by JTL, a provider of accredited training courses for professionals who have already achieved qualifications in their field. JTL has UKAS accreditation to the International Standard ISO/IEC 17024.

JTL works in association with the Engineering Equipment and Material Users Association (EEMUA), and CompEx has the support of the Health and Safety Executive (HSE), which is the independent regulator for health and safety at work, as well as NICEIC, the UK’s leading voluntary regulatory organisation for the electrical contracting industry.

Licenced centres for CompEx testing can be found across the globe.


CompEx accreditation is fast becoming essential for electrical engineers working in potentially hazardous or explosive environments.

By ensuring that its staff are fully qualified and accredited, AES is protecting their health and safety, along with the employees of the companies we work with.

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Advanced Electrical Services (YKS) Ltd
1 Waterworks Cottages, Pildacre Lane, Ossett, West Yorkshire WF5 8HN

01924 283 737

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