Earthing – the silent hero in the fight against explosions. Why is it so crucial in Ex zones?
Inconspicuous, invisible, yet absolutely crucial. Earthing in potentially explosive atmospheres is something that is rarely discussed – until the worst happens. And one mistake is enough to cause sparks and ignition. In this article, you will find everything you need to know about the role of earthing, the effectiveness of systems, and the risks that begin where awareness ends.
Installation without earthing? This is not an oversight – it is a hazard.
If you do not have proper grounding, you risk a spark that could result in an explosion. Not figuratively – literally.
Here is what happens when there is no grounding:
the electrostatic charge has nowhere to discharge, so it remains in the tank, tanker, hose or installation,
Provide your company with a risk assessment that genuinely improves security.
one touch, movement or rub – and a spark appears,
flammable mixture + spark = ignition.
It does not take a lot of energy. Just 0.2 mJ is enough to ignite solvent vapours. For comparison, that is less than what it takes to turn a key in a lock.
This was the case, for example, with the explosion at the Barton Solvents plant. The tanker was not earthed during reloading – and in a second, the vapour cloud ignited. The result? Destruction, losses and an investigation. All because of something that could have cost a few hundred zlotys.
So don’t ask “is it worth it” – ask yourself if you can afford to skip grounding when the risk is so real and the solution so simple.
And if the topic of grounding is just the beginning, see what else is worth checking in your installation. In this guide, we show you how to conduct a step-by-step explosion risk assessment and what to pay particular attention to in Ex zones.
The role of earthing in Ex zones – inconspicuous but crucial
Earthing protects against electrostatic discharge, which can cause ignition. This is its basic – and most important – function.
Why does it work?
- Because earthing allows charges to be discharged before they reach a critical level.
- Because it connects all elements of the installation to a single potential, preventing sparking between them.
- Because it provides control over energy that would otherwise be chaotic and dangerous.
But – and this is important – earthing is not just a cable thrown into the ground somewhere. It must be:
- continuous and verifiable (tested at least once every two years),
- resistant to external factors (chemicals, moisture, mechanical damage),
- compliant with standards (PN-EN 60079-0 and 60079-14).
It is not enough to just “screw something in place”. Effective earthing is a whole procedure: from design, through material selection, to installation and final testing. Without this, you cannot be sure that the system works – and in an Ex zone, there is no room for guesswork.
Types of earthing systems – the choice depends on what you do
Not every earthing system will work in every installation. What works in a chemical plant will not necessarily be suitable for a fertiliser warehouse or a mobile loading station.
Which systems can you use?
- TT system – recommended when it is not possible to use a common earthing point (e.g. in containers, temporary facilities).
- TN-S system – best for stationary industrial installations; PE and N cables run separately.
- IT system – less commonly used, but can be useful in specific process systems.
- Local earthing (e.g. for tankers) – with continuity monitoring and process lockout in the event of a disconnection.
It is important not to copy solutions from the internet. Just because something works for your neighbour does not mean it will work for you. Different environments, different materials, different risks.
Therefore, before you buy another cable with a clip, consider whether you have a system or just a cable. And if you are not sure, just contact us – we will help you choose something that will actually work.
Grounding connection in practice – one mistake and it’s all over
An incorrect earth connection is essentially no earth connection at all. Even if the cable looks fine and is in place, this does not mean that it is working.
What do you need to pay attention to when connecting the earth?
- The contact point must be clean, degreased and free of paint.
- The clamp should cover the bare metal surface, not the insulation or varnish.
- The length of the cable should be adjusted to the workstation, without tension or kinks.
- The connection must be mechanically secure and must not “fly off” or fall out when moved.
- The conductivity test should show a resistance of ≤ 10 Ω.
In theory, it’s simple, but in practice, too many installations have a loose cable with a clip that “usually works”. And then we wonder where the spark came from.
In the industrial plants we audit, over 40% of earthing points do not meet the requirements of PN-EN 60079-14. And it is not because someone is trying to save money. It is simply because the issue is treated as a formality – “there is a cable, so it’s OK”. It is not OK.
That is why more and more companies are opting for systems with automatic continuity monitoring – if the cable is not working, the system will not start the process. And that is how it should be. People can make mistakes, but the system is there to prevent errors.
The effectiveness of grounding is measured by facts, not beliefs.
Earthing does not work “by eye”. Either it conducts or it does not. The only way to check this is by taking measurements.
What needs to be measured and monitored?
- Ground connection resistance – no more than 10 Ω (for installations without power supply),
- continuity of grounding conductors – from point to point, without interruptions,
- quality of contacts – no corrosion, loose screws, lack of mechanical contact,
- periodicity – measurements should be performed at least every 24 months,
- documentation – everything must be recorded in reports, available during the audit.
It is not enough to say “we measured it once” or “the electrician said it works”. Without hard data, you have no certainty. And in the case of an inspection by the Technical Inspection Authority or a health and safety inspector, it is the measurements that will form the basis for assessing the condition of the safety measures.
More and more plants are implementing periodic resistance tests and systems for recording measurement results, e.g. weekly or after each shift change. In this way, they not only meet the requirements, but also build a real safety culture in which earthing is not a formality, but a practice.
Do you want to be sure that your systems are working? Choose equipment with a control function, ready documentation and the possibility of integration with operational procedures.
A grounding system is more than just a single cable
Earthing is not a cable. It is an entire system designed to work at all times and under all conditions. And only as a system can it provide real explosion protection.
What makes up an effective earthing system?
- Grounding point – permanently connected to the ground, protected against damage.
- Clamp – Ex-certified, with adequate clamping force and durability.
- Cable – abrasion-resistant, flexible, usually with steel braiding or a chemical-resistant coating.
- Signalling – optical or acoustic, indicating correct connection.
- Control module – blocking the process in the event of discontinuity.
- Regular tests – confirming the effectiveness of the entire system.
If any of these elements fails, you do not have a system, only a substitute for it. It is a bit like having a seatbelt that only works at low speeds.
If you are interested in how a small amount of energy can cause ignition, be sure to read the article on minimum ignition energy (MIE). This parameter shows how little it takes for a faulty earthing system to cease to be just a fault and become a real hazard.
Atex Doradztwo offers complete earthing kits, including:
- self-retracting cables for tanks, IBCs and barrels,
- grounding points for wall and floor mounting,
- systems with LED lights and audible signals,
- ATEX and IECEx certified kits – ready for implementation in Ex zones.
If you are unsure whether your system is working as it should, check it now. Or contact us. It is not an investment – it is a necessity.
Finally, do not take risks where you can take action.
One mistake is enough to lose everything – and earthing is exactly the point that cannot be overlooked. Sometimes it is just a cable, sometimes the entire installation. But always: it determines the safety of people, the process and the company.
If you are not sure whether your system is working as it should – check it now.
If you don’t have one, don’t delay in implementing it.
At Atex Consulting:
- we will advise you on the best system for your installation,
- we will prepare solutions compliant with ATEX, IECEx and PN-EN standards,
- we will provide components and complete sets (including mobile and continuity control sets),
- we will help you implement earthing as part of a comprehensive explosion protection project.
Would you like to learn more or require a quote?
Contact us – we will quickly assess the situation and suggest solutions that really work.
Frequently asked questions about earthing in Ex zones
Is earthing mandatory in Ex zones?
Yes. It is required by both the ATEX directive and Polish law (Labour Code, Regulation on occupational health and safety for energy equipment). Failure to ground Ex zones is considered a serious negligence in terms of explosion protection.
How often should the effectiveness of earthing be checked?
At least once every 24 months – this is the recommendation resulting from the PN-EN 60079-14 standard. In practice, in the case of intensively used stations (e.g. tanker reloading), inspections may be required even every few weeks, especially if the cables are exposed to mechanical damage or corrosion.
Is a regular cable with a clamp sufficient?
No. Earthing is not just a cable – it is a system. Is there no signalling? No confirmation of circuit continuity? Is the connection loose or corroded? This means that the earthing is not fulfilling its function, even though it is “there”. The use of cables without ATEX certification in potentially explosive atmospheres is unacceptable.
What are the symptoms of ineffective earthing?
Most commonly:
lack of process control by the system (e.g. the indicator light does not come on),
visible signs of sparking on the terminals,
frequent electrostatic discharges felt by employees,
excessive cable resistance (>10 Ω).
If any of these signs occur, stop work immediately and check the system.
Can tankers and barrels be earthed using the same system?
Not always. The requirements for tankers are higher – among other things, it is necessary to check the continuity of the grounding and automatically block the process if the connection is not confirmed. In the case of barrels and IBCs, manual systems with signalling are acceptable, but they must comply with standards and be tested regularly.
Does earthing also protect against electric shock?
No. Explosion protection earthing systems are designed to protect against electrostatic discharges – they do not replace electric shock protection. These two systems can coexist, but they have different functions, designs and control points.
