Static Electricity FAQs: Your Question & Answer Resource
Can static electricity cause a fire? Is static electricity an ignition source?
Yes – static electricity can be an ignition source for operations conducted in EX atmospheres. If equipment engaged in processing or transporting flammable or combustible products is allowed to accumulate static charge, the voltage increase could exceed the breakdown voltage of the surrounding atmosphere, leading to an electrostatic spark discharge.
People can also accumulate static charge to carry enough energy, which, if released in the form of a spark, can ignite a flammable atmosphere. Watch this video* showing an actual refuelling fire incident.
*Disclaimer: Third-Party YouTube Videos:
This video is provided by a third-party YouTube channel and used for illustrative purposes only. We do not own or control the content, and the views, opinions, and information expressed in this video are solely those of the original creators.
Why and how is static electricity an ignition source for Road Tankers etc.
- Road tankers / Tanker trucks?
- Vacuum trucks / Vacuum tankers?
- Flexible Intermediate Bulk Containers (FIBCs)?
- Rail tankers / Railcars?
- Drums?
- EX IBCs / Totes?
- Fluid bed driers?
- Metal piping?
- Mixing vessels?
Electrostatic charge generation could occur in processes involving the movement of liquids and powders. Metal equipment could accumulate an electrostatic charge if it is not connected to the general mass of the Earth. Because most of the equipment referenced can be moved or is designed to move, this prevents permanent connections to the general mass of the earth through installed grounding networks and building structures.
Therefore, temporary connections to Earth should be made when the process is underway to mitigate an uncontrolled electrostatic discharge. A target threshold resistance of 10 ohms between the equipment and a verified true earth grounding point is recommended in a wide range of industry publications.
For non-metallic containers like Type C FIBC, the same principles apply, but the resistance threshold differs.
What should I do to prevent fires caused by static electricity?
There are multiple ways of mitigating fires and explosions on sites where flammable products are processed and transported.
With regard to controlling static electricity, various methods can be adopted. Grounding is an easy but effective way of providing a path to earth for electrostatic charges. This mitigates the accumulation of static electricity on the metallic equipment being used in the process, which, in turn, reduces the voltage to a negligible level incapable of discharging an electrostatic spark.
What is static earthing / grounding?
Earthing (sometimes referred to as grounding) is the process of providing a path to the general mass of earth in order to dissipate electrostatic charge, bringing equipment to earth potential (0V). This helps avoid the equipment from reaching a voltage high enough to discharge an incendiary electrostatic spark.
Quotes from IEC 60079-32-1 and NFPA 77:
Section 13.1. of IEC 60079-32-1: “By far the most effective method of avoiding hazards due to static electricity is to connect all conductors to earth. This will avoid the most common problem which is the accumulation of charge on a conductor and the release of virtually all the stored energy as a single spark, to earth or to another conductor.”
Section 6.8.2 of NFPA 77: “As defined in 3.3.23, grounding is the process of bonding one or more conductive objects to the earth so that they are all at zero electrical potential.”
Section 3.3.23 of NFPA 77: “Grounded (Grounding) Connected (connecting) to ground or to a conductive body that extends the ground connection. [70, 2023].”
What is static bonding?
Bonding provides a low-resistance electrical connection between two pieces of metallic equipment so that electrostatic charge is distributed equally, thereby bringing them to the same electrical potential. If they are at the same potential, then there will be no static spark discharge between them.
This does not mean that static discharges to objects at a lower voltage are prevented.
Quote from IEC 60079-32-1:
Section 13.1. of IEC 60079-32-1: “Bonding is used to minimise the potential difference between conductive objects to an insignificant level, even where the resulting system is not earthed. Earthing, on the other hand, equalises the potential difference between the objects and the earth.”
How can I stop static electricity in my process?
Due to the interaction of certain types of materials, the generation of static electricity cannot be “designed out” for all processes conducted in EX areas. As far as metallic equipment is concerned, earthing / grounding is an easy and effective way of mitigating the accumulation of static electricity. By finding a method, through either permanent or temporary methods, of connecting the equipment to earth, the accumulation of static electricity to hazardous levels is prevented, thus mitigating the risk of an electrostatic spark in the EX area.
Technical Specifications like IEC 60079-32-1 and NFPA 77 provide extensive information on the ignition hazards of static electricity and Best Practice methods that can be adopted to manage the risk. Industry-specific publications are also available (ACA, ESIG).
What solutions can I buy to stop static electricity?
The “right” solution depends on several factors:
Equipment to be grounded: Newson Gale offers grounding solutions for various types of equipment, including:
Road tankers / Tanker trucks
Vacuum tankers / Vacuum trucks
Rail tankers / Railcars
FIBC (Type C)
EX IBCs/Totes
Drums
Mixing vessels
Interconnected process equipment (e.g., fluid bed dryers, piping)
Bulk transfer systems (e.g., LACT units
Level of control desired: Consider the following questions:
- Do you need visual confirmation of the ground connection?
- Do you want to monitor the electrical and mechanical performance of the ground connection during the process?
- Would you like interlocks to prevent the process from starting unless a verified ground connection is in place?
- Are you comfortable with a passive solution that only relies on the quality of the mechanical connection?
Hazardous location certification requirements: This will determine the necessary EX certification for the grounding equipment.
The easiest way to find the right solution is to contact one of our Regional Sales Managers. They can visit your facility to discuss your application and installation requirements, or you can schedule an online meeting to explore our wide range of options.
What is the difference between 10 ohms and 1 meg ohm for static grounding reasons?
The breakdown voltage of air refers to the voltage required to ionise the air, making it conductive. At ambient temperatures and pressures, this value is around 3kV per mm. When the voltage exceeds this threshold, the air becomes conductive, allowing static electricity to discharge as a spark.
This occurs when an ungrounded object, like a tanker truck/road tanker, is filled with electrostatically charged liquid or powder. Eventually, the voltage of the tanker truck/road tanker exceeds the breakdown voltage of the surrounding atmosphere. The safety concern arises when another conductor, like a person or a fill pipe, is nearby. An electric field forms between the charged object and the conductor. When the electric field strength is exceeded, the air is ionised and becomes conductive. This allows the static charge to pass through the air to another conductor. Energy is released as a spark when this happens.
What is meant by the “breakdown voltage of air”?
Electrostatic charging currents are much smaller than electrical currents circulating on power networks, and therefore, due to the low charging current range, the corresponding value of 1 meg ohm is considered adequate for the safe dissipation of static electricity.
However, when static poses an ignition risk in EX atmospheres, a lower resistance of 10 ohms is recommended for metallic equipment (e.g., drums, totes, EX IBCs, road tankers). This is because any resistance above 10 ohms in these metal circuits suggests potential degradation or breaks, which can prevent the effective discharge of electrostatic charge to earth.
Quotes from IEC 60079-32-1 and NFPA 77:
IEC TS 60079-32-1, section 13.2.2 “Practical Criteria”: “Metallic items in good contact with earth should have a resistance to it of less than 10 Ω. Although a value of up to 1 MΩ is acceptable for static dissipation, values above 10 Ω may give an early indication of developing problems (e.g. corrosion or a loose connection) and should be investigated. It is important that all connections are reliable, permanent and not subject to deterioration.”
NFPA 77, section 7.3.1.6.1: “Where the bonding/grounding system is all metal, resistance in continuous ground paths is measured to verify mechanical integrity. (See A.3.3.2.) Such systems include those having multiple components. Greater resistance usually indicates that the metal path is not continuous, usually because of loose connections or corrosion.”
Where does Newson Gale ship products to? How can I get Newson Gale products?
Newson Gale has warehousing facilities in the UK, Germany, China, and the United States, where we sell directly to end users. We also have a network of authorised distributors in Europe, South America, the Middle East, India, South East Asia, and Australia.
Newson Gale ships products across the globe. We can do this because we carry EX equipment certificates for a wide range of country-specific regulatory requirements.
Does Newson Gale do anything apart from static grounding?
No. Newson Gale focuses exclusively on the design, manufacture, marketing, sale, and distribution of static control equipment for customers participating in the EX-certified industries.
What warranty does Newson Gale offer on its equipment?
Because we design and manufacture our electronic circuits, we can offer customers a 7-year warranty against manufacturer’s defects on Newson Gale PCBs.
Our clamps and cables are designed and quality-controlled to our specifications. We offer customers a 1-year warranty on mechanical parts.
How long has Newson Gale been in business?
Newson Gale has been supplying the hazardous process industries with static control solutions since 1982.
In 2016, Newson Gale was acquired by the HOERBIGER group and is a constituent brand of HOERBIGER Safety Solutions.