Sometimes one of the outlets of an electrical junction box or electrical conduits does not need to be used; however, leaving them open allows dust and moisture to enter this equipment and increases the likelihood of electric shock and deterioration of electrical cables. The plastic cap is a small part with standard dimensions that can close the outlet in these conditions and prevent dust, moisture, and external factors from entering this equipment in the power distribution system. The installation of this part is very easy and only requires twisting it by hand or with a screwdriver into the hole or electrical conduit.
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Plastic electrical caps come in two types: female and male. Since steel electrical conduits each have different internal and external threads, the caps must also be manufactured differently to have the necessary compatibility with them.
Female plastic cap: If there are threads on the outside of the steel electrical conduit, a female plastic cap must be used. The threads of this type of cap are directed inward and match the external threads of the electrical conduit.
Male plastic cap: If the threads of the steel electrical conduit are on the inside, external threads on the plastic cap are required. This type of cap is known as the male plastic cap, which has full compatibility with the mentioned conduits.
The inlet holes of junction boxes have different but standard diameters that allow steel electrical conduits to be placed inside them. Since plastic caps, in a way, replace the electrical conduits inside these boxes, their dimensions must also be compatible with the electrical conduits. Among the common sizes of plastic caps are:
The dedicated plastic cap for the junction box is an important and widely used part in the power distribution system. The correct selection and proper purchase of this part for its installation and preventing the entry of dust is very important. In the continuation of the article, we intend to examine important tips for purchasing these caps:
Purchase after the completion of electrical conduit installation: Usually, at the very beginning of the work, it is not clear how many plastic caps are needed for the junction box. Therefore, it is better to postpone its purchase to the end of the work when you are sure of the required quantity.
Paying attention to sizing: Plastic caps are produced with various PG ratings, the most common of which are from size 11 to 29. Be sure to consider the compatibility of the cap with the hole size of the junction box.
Compatibility with conduit threads: If the plastic cap is used for electrical conduits, be sure to pay attention to the thread location (inside and outside) and compatibility with the electrical conduit. The conduit threads must be the reverse of the plastic cap threads.
Durable material: Check the flexible and durable material of the plastic cap. Polymer caps with high resistance can have good durability and performance.
Although plastic caps with threaded bases are more suitable for boxes with threaded inlets and outlets, specific types of these caps have also been designed for other electrical boxes, such as plastic junction boxes and galvanized junction boxes, allowing you to block the open openings of these boxes.
In the design of specific models of plastic junction boxes, there is a knock-out feature, meaning a layer of plastic or metal in the hole openings can be detached. Therefore, when you do not need to install conduits in some of the junction box holes, you can simply not remove the knock-out layers. However, for aluminum models and cast iron boxes, there is threading inside the punch, into which you can easily screw the plastic cap.
Therefore, these caps have various designs and each is usable for electrical boxes. Not only for junction boxes, but electrical panels and boxes connected to conduits may also need these caps. Overall, the use of this plastic cap is very vital and essential.
Imagine if various types of plastic caps in different models had no threads at the entry point to the punch opening. In that case, their stability would not be complete, and they could detach from their place with the slightest stress or impact. Therefore, design engineers have made it so that, in order for these plastic caps not to be able to detach from the box body, you must repeatedly screw them into the punch.
This matter is especially important when junction boxes are exposed to high stresses. Of course, these caps are only used for boxes with simple applications and do not have specific functionality for types of junction boxes such as explosion-proof types. For this reason, we must be careful about what type of caps we purchase for what type of boxes.
One of the fundamental questions raised is precisely this matter. In fact, you need to see how many of the box body punches are empty so that you can proceed to purchase plastic caps. Therefore, it is certainly not necessary to buy these caps alongside the boxes; you can do so after the completion of the project and the installation of the electrical boxes as well as the electrical conduits. This approach has several important advantages for you. Firstly, your cost is preserved for the exact number of these caps, and they will not be surplus after the work is finished.
Very hard and resistant polymers are used to produce plastic caps for junction boxes. Their dimensions are also completely specific and based on the standards related to the size of the punch openings on the box body. However, if you wish to purchase your junction box without punches or holes, you can consult with manufacturing groups regarding the exact dimensions of these caps. As a result, it is possible to change the size for manufacturing these caps. As you can see in the images, due to easy installation and high safety, these caps are also threaded. These parts do not have a complex structure and are designed and manufactured in high quantities by domestic manufacturing groups, so they also have an affordable price that varies based on size.
Generally, cabling networks designed using junction boxes and electrical conduits, as well as the terminals inside these boxes, must be at the highest level of safety. The occurrence of even the slightest damage at the terminals or the cable connection point not only takes the electrical current out of the network or circuit but can also cause short circuits or fires. Therefore, the simplest thing is that the connections located inside the terminals of the junction boxes are isolated from external environmental factors.
Although these junction boxes provide good physical protection for the connection points, a small oversight, such as leaving the conduit entry point open or not using a plastic cap on the junction box, increases the risk and probability of network damage. We must always try to use even the smallest accessories, whether a cap or even a simple screw, to enhance cabling safety.
Every device and piece of electrical connection support equipment, as well as cables, has a set of accessories that complete the network. In the case of junction boxes, the plastic cap has been designed and manufactured. Of course, these caps are not always used; rather, they are for situations when the entry point of the electrical conduit into the junction box is completely free and its opening must be blocked.
It is in such conditions that the plastic cap can be used. Generally, junction boxes must not only be placed in a completely safe environment, but their connections must also be in accordance with defined standards. In some cases, you may have observed all the principles and rules related to the installation of these distribution boxes, but due to an open hole or opening in the distribution box body, the entire project is exposed to high dangers and risks.
Therefore, we must always follow all the details related to installation according to predetermined principles. It does not matter in what position these boxes are installed. We cannot use a round plastic cap based on assessing the installation position of these boxes.
In any case, if one or two conduits are not connected to the junction box body, we must use these caps. Some people, due to the lack or unavailability of these caps, may try to block the conduit entry point to the box with miscellaneous items. However, these items detach from the box body after a while, and it is better to use these plastic caps, which have a threaded or screw structure, so that you can easily screw them into the opening of the hole.
As mentioned, the main priority is establishing safety during the installation and implementation of the cable support network, as well as connecting distribution boxes, and also after the work is completed. If you pay attention to the body of these boxes, they have very high resistance. In addition, to insulate and separate the connections and terminals inside the box from the outside environment, a cover is also used.
Covers exist for all distribution boxes. These covers are used on the body of plastic junction boxes, aluminum, galvanized, and even stainless steel types. All of these pursue specific objectives, which are to prevent damage or contact at the connections and terminals. The body hole caps pursue exactly the same objective.
Failing to block the body holes of the box will allow any type of external element to enter the junction box. Even simple dust, by settling on the connections, causes disruption in the electrical current. Furthermore, if the work and industrial environment contains fine particles, dust, and even flammable gases, in the event of a short circuit inside the box, a fire incident will be certain.
Of course, this matter applies more to explosion-proof junction boxes. However, in any case, the environment inside the box or junction box must not be in contact with the surrounding space, and all openings or holes must be closed with plastic caps. In the production of plastic caps, the approach of size variety is also considered.
The plastic cap for the electrical junction box is made of the highest quality structured PVC polymers. These caps are often used to protect the end of PVC electrical conduits. Their plastic material has a high density, and for this reason, they are considered hard polymers. Due to their threaded design, they are easily able to be opened and closed.
Numerous advantages can be listed for hard PVC material, including a completely fireproof structure and resistance to environmental factors such as moisture. Moreover, they do not have a dry and brittle nature, and with the slightest application of force, they do not suffer structural deterioration, deformation, or thread breakage. Therefore, if used correctly and properly, they will work for you forever, and there is no need for repurchase in subsequent time periods.
Since the holes of electrical junction boxes have various dimensions in terms of size and diameter, the caps have also been designed and manufactured according to this same sizing. Among the common and widely used sizes available for the plastic cap for junction boxes are sizes PG11, PG13.5, PG16, PG21, and PG29. Therefore, it covers a wide range of sizings, and you can use this plastic cap for any type of junction box that has threaded holes.
Up to this point, we have fully introduced the various types of plastic caps for junction boxes. Given that these caps have different types and are used for numerous applications, in the continuation of the article, we will describe its other models.
The plastic cap is an accessory part used with various types of steel electrical conduits. Due to their design type and structure, these caps are usually used at both ends of the electrical conduit. High manufacturing quality, elastic structure, and easy and simple application are valuable features of this product. Numerous advantages can be listed for using plastic caps for greater protection of electrical conduits.
Although they are considered an accessory or minor part, failure to use them has, in some cases, led to damage to steel conduits. The question may arise for you as to how these caps can provide greater safety for conduits. In this article, we intend to fully introduce the plastic cap and discuss its functional mechanism and the objectives related to using these caps. So please pay attention to the continuation of the article.
These caps are used so that conduits are transferred to the project site completely sound, intact, and without minor or major damage. Given the relatively long length that conduits have after packaging, their two ends must be completely blocked. The type of polymer and the material used to manufacture the plastic cap is very high-grade and of high quality.
Specifically, it has good elasticity and flexibility properties. As a result, conduit packaging workers can easily place them on the two ends of the conduit. Furthermore, if the conduits are exposed to impact or falling from a height, the external threads do not suffer breakage or deformation. They are used not only for various types of electrical conduits but also for a wide range of pipes intended for fluid transmission. Of course, a different structure of the plastic cap will be designed for such pipes.
These caps do not easily tear or corrode. Their dimensions are designed with complete precision so that when placed at the end of the conduit, they fit perfectly onto them. In such a way that during installation, they cannot be easily detached, and you must apply a relatively high force to be able to remove these caps from the conduits.
This is considered a very important and valuable advantage, ensuring that we will not witness the accidental opening of the plastic cap during the transportation and transfer of conduits. Such protective measures are taken for conduits, whereas the electrical conduit fittings are transported separately to the project site.
As mentioned, the plastic cap is placed at both ends of the steel electrical conduit. To answer the question of what the objectives of using plastic caps are, we must say that when steel conduits are designed and manufactured and are ready to be sent to the market, numerous stresses threaten them. Dust or moisture may penetrate inside the conduits, so these environmental contaminants can certainly destroy the internal structure of the conduit quite gradually. Consequently, when you place the cables inside the conduits, ideal physical protection cannot be provided.
In addition, various objects and elements may settle in the internal path of the conduit and cause blockage. Blockage inside the conduit disrupts their use. Therefore, in industrial projects, the inside of the conduits and their internal wall must definitely be completely sound. When plastic caps are placed at both ends of the conduit, they both prevent moisture and dust and can also prevent the entry of objects that could block the conduit. So, as you can see, although it is a minor and small part, it is extremely valuable and has a technical application.
The threads are a very vital element on steel electrical conduits. These threads provide the conditions for the screwing operation of the fittings to be carried out well. But the very important point we must pay attention to is that, due to the delicate structure of the threaded area, it practically has the ability to be damaged by impact or any external force and pressure.
Therefore, we must take all necessary measures for the physical protection of this area of the conduits. This damage can occur in the times after production, such as during the loading and unloading of the conduits. However, if you use a plastic cap on the threads of the conduit, you have certainly prevented any damage to them. By using the plastic cap, you will no longer witness breakage or chipping of the conduit threads.
The plastic cap is classified into two types: male and female. Types that are designed and manufactured as male can be placed inside the conduit. Female types of the plastic cap for steel electrical conduit are generally placed on the external part of the conduit and over the threads. Each of these, in terms of functional features, can provide good protection against the penetration of any external factor into the conduit.
If the external part of the conduit and also its end area does not have threads, you can purchase the male types of plastic caps. However, if both ends of the conduit have threads, you must definitely be careful to use the female models of the plastic cap to provide ideal protection over the external threads of the conduit.
Steel electrical conduits, in order to have the capability of supporting and protecting most electrical cables, are generally designed and manufactured in various sizings. The diameter of these conduits varies and they are classified from small to large types. Regarding the selection of the plastic cap for steel electrical conduits, we must always keep this rule in mind: obtain caps that are completely compatible in size with the intended conduit. Naturally, you cannot use small-sized caps for conduits that have a larger diameter.
Although these caps have a plastic and flexible structure, this does not mean that you can, by applying extra force and pressure, use them on conduits that have a larger diameter. The sizings considered for these parts are exactly proportionate to the size of the conduits. As you know, the sizes of steel electrical conduits range from PG13.5 to PG48. Therefore, at the time of purchase, by providing the conduit size, you can buy the appropriate cap for the intended conduit.
In general, three stages are considered for the movement of conduits. These stages include loading, transporting the conduits, and finally unloading them. At each of these stages, there is a possibility of damage to them. Therefore, you can create complete safety during the transportation of conduits to the project site by using the plastic cap.
Dear customers, in addition to obtaining various types of plastic caps, can purchase other practical parts such as couplings, pull tees, conduit bodies, and clevis hangers as the most important connecting parts in conduit networks from Rafi Industrial Group. To receive supplementary information regarding the purchase of products and to learn about their prices, contact our experts.
