Selecting an appropriate explosion-proof junction box is essential for safeguarding your electrical connections while working in a potentially dangerous environment. Curious to know which aspects matter the most? In this guide, you will learn about concepts that you must consider – such as material, IP rating, and zone classification – that make your compliance possible even under harsh conditions.
1) Explosion Classification
Understanding explosion classifications is essential for choosing the right specifications for your junction box. There are basically 2 standards known in the world and they differ mainly in their regional focus and approach to safety classifications;
- The NFPA (National Fire Protection Association), widely used in North America, focuses on fire prevention and safety, using the “Class, Division” system to categorize hazardous areas.
- IEC (International Electrotechnical Commission) standards, internationally recognized, use a “Zone” system that more specifically defines explosive risks based on the frequency and duration of hazards.
Both aim to ensure safety but vary in their classification methods and terminology.
| NFPA standards | |||
| Class I | Class II | Class III | |
| Division I | Locations where flammable gases or vapors are present in the air under normal operating conditions (e.g., oil refineries, chemical plants). | Locations where combustible dust is present in the air under normal operating conditions (e.g., grain handling facilities, food processing plants). | Locations where easily ignitable fibers or flying particles are present in the air under normal operating conditions (e.g., textile mills). |
| Division II | Locations where flammable gases or vapors are present only in case of a leak or under abnormal conditions (e.g., areas near fuel storage). | Locations where combustible dust is not normally present but may accumulate in the event of a spill or malfunction (e.g., certain manufacturing areas). | Locations where ignitable fibers or particles are not normally present but may accumulate (e.g., storage areas for cotton or other fibers). |
| IEC standards | |
| Description | |
| Zone 0 | Areas where an explosive atmosphere consisting of a mixture of air and flammable substances is present continuously or for long periods. Example: Inside a fuel storage tank. |
| Zone 1 | Areas where an explosive atmosphere is likely to occur in normal operation. Example: Locations near pumps and valves in oil refineries. |
| Zone 2 | Areas where an explosive atmosphere is not likely to occur in normal operation and, if it does occur, will exist only for a short time. Example: Areas surrounding storage tanks. |
| Zone 20 | Areas where combustible dust is present continuously or for long periods. Example: Inside a grain silo. |
| Zone 21 | Areas where combustible dust may be present in normal operation. Example: Areas around powder handling equipment. |
| Zone 22 | Areas where combustible dust is not likely to occur in normal operation and, if it does occur, will exist only for a short time. Example: Areas surrounding dust collection systems. |
2) Material
The materials used in making the junction box explosion-proof determine its efficiency and durability. Such studies like this one carried out by NIOSH indicate that corrosion can account for about 25% of all industrial equipment failures, making proper material selection quite critical.
You may opt to use aluminum owing to its strength-to-weight ratio and its noncorroding qualities or stainless steel which will be suitable in environments that are extreme.
Consider in case your junction box will be used within an offshore oil rig then you would want to use stainless steel 316, with great resistance to chemical and saline environments. For people who are in a highly corrosive atmosphere then fiberglass may be a good material option as it is a nonconductor. Therefore getting the materials is the key to survival in harsh environments and performance stability.
3) Ingress Protection (IP) Rating
Ingress Protection (IP) ratings are crucial in assessing the standards of junction boxes and how well they can repel dust and water. An IP rating is made up of two numerical digits, the IEC states;
- The first one shows how much protection it has against the ingress of dust,
- The second shows the degree of water resistance.
A good example is if you are in need of a box that can operate in damp and dirt surroundings, then one with an IP67 enclosure is appropriate since it provides protection from immersion in water.
Such a level of protection is most useful in cases of treatment facilities and it increases safety and dependability. It is possible to diagnose that a junction box will work even under unfavorable conditions with the appropriate selection of IP rating.
4) Size and Capacity
While deciding upon the dimensions and volume of your explosion-proof terminal box, it is important to note that sufficient distance is vital for good installation. In its standards, the NFPA states that at least 20% additional capacity should be added to the expected number of circuits. For instance, 12 or 15 circuit space should be considered if the requirement is 10 circuits.
U.S. Electrical Safety Foundation has reported that every year there are nearly 23,000 household catch fires due to electrical overheating and short circuits. This is useful in avoiding overheating and reducing the likelihood of electrical problems. Letting your terminal box have enough room on the inside will aid in safety, ventilation, space management, and troubleshooting and repairs.
5) Mounting Options
When choosing a mounting type for your explosion-proof box it is important to think how you are going to install it based on your specific requirements. According to statistics, improper mounting leads to failure of the equipment in even 15% of installations, thus it’s essential to make a wise decision.
For instance, in factories where equipment gets exposed to heavy machinery, surface-mounted boxes are very common whereas flush-mounted boxes may be used in clean rooms with high use of space. Ensure that the junction box you select is equipped with the suitable types of hardware and functions that will allow for quick installation. The right mounting will not only offer stability but also prolong the life span of your junction box.
6) Certifications
Certifications play a major role in assuring that your explosion-proof electrical box complies with industry safety standards. According to IEC’s report, devices that have certification can lower the chances of electrical failure by as much as thirty percent. Some look for junction boxes bearing ATEX, IECEx, or Underwriters Laboratories (UL) certification.
For example, UL certification is quite common in the United States while ATEX certification is a must for explosive atmosphere equipment if you’re in Europe. You can trust the effectiveness of the product in averting explosion-related accidents considering it is certified. You can never go wrong but rather always double-check the certification papers for validity and conformance.
7) Temperature Ratings
When operating in extreme conditions, temperature ratings become vital for an explosion-proof junction box to function appropriately. Each of these junction boxes has a temperature rating which shows the minimum and maximum temperature range for its functioning without failure.
As ASHRAE points out, the use of equipment at temperatures not recommended can result in system breakdowns which can be expensive and result in system downtimes. Take into account, for instance, the temperatures of the area.
If one is installing a junction box outdoors in a very cold or hot region, try finding one with a rating of -40°C to 60°C (-40°F to 140°F). Keeping operating temperatures under control will help prevent occasions where the junction box is prone to overheating thus improving its longevity in terms of safety and reliability.
➔ Conclusion
An ex proof junction box is crucial in dangerous areas. However, it is important that zone classification, IP rating, and material are considered to ensure that the explosion-proof junction box can offer the best protection where needed.
Hexlon provides a wide selection of the best quality explosion-proof junction boxes. Do not worry, our qualified personnel will assist you in choosing the most effective products or solutions for your needs. Contact Hexlon for professional assistance and reliable products.
