All electrical wiring must be safe for human life. This is one of the most basic requirements for electrical installations. It is especially necessary to remember the places where the wires are connected, because it is there that overheating, contact failure or even fire can occur. That is why reliable insulation should be made in these places. One way to insulate is to use heat shrink tubing (HERE). This type of protection has many advantages over other types of protective insulation for cable connections. But in order to use the heat shrink correctly, you need to know what it is, what such a tube is for, and how to choose the size. This is what this article will be about.
Content:
- Main purpose
- Advantages and disadvantages
- Where is the tube used HERE
- Heat shrink tubing specifications
- How to use heat shrink for wires
Main purpose
The main purpose of heat shrinkage is to insulate live conductors. Due to its electrical insulating properties and easy installation, it is possible to successfully replace conventional insulating tapes.
At this time, you can easily purchase heat shrink tubes in electrical stores, which are used to protect wire connections. The popularity of this product as an insulating material lies in the ability to reduce its diameter due to the high temperature. The required shrinkage temperature reaches 120 ° C. However, in order to do this, you need to know how to heat the heat-shrinkable tube. Due to the heating, the heat shrinkage very tightly and reliably covers the insulated object, providing good insulation, as well as providing mechanical protection for the wires.
Tubes are available in different sizes and color coded by manufacturers. Due to this, they are used not only for good insulation, but also for further determining the purpose of the insulated wire.
For example, to mark DC wires, use red for plus and black for minus. And for marking five-core electrical cables, brown, white, black are used, which denote phase conductors, zero is indicated in blue, grounding is yellow-green.
The use of HERE for cable marking is quite convenient, because the heat-shrinkable tube does not need to be pulled over the entire length of the wire. It is only necessary to pull a small piece of heat shrinkage over the insulation onto the end of the wire, as shown in the photo above. This marking is very reliable, and is not afraid of external influences, as well as temperature changes. Its service life is more than twenty years. This product is durable, inexpensive and very easy to use.
Advantages and disadvantages
Compared to other types of insulation, heat shrinkage has at least four advantages.
Firstly, since the heat shrink tubing fits very tightly, it does not move due to various mechanical influences. Secondly, the installation is a simple and quick process, but you still need to know some rules of use. Thirdly, after shrinkage, the insulation material becomes more durable, so the wire becomes even more resistant to mechanical damage and gains additional rigidity in place connections. And the service life is much longer than that of ordinary electrical tape. The fourth plus is a wide range of applications.
Of the disadvantages of the HERE tube, the following can be noted:
- It is impossible to reuse, because when heated, it changes its diameter, so it will be damaged when removed.
- The price of a heat-shrinkable tube is more than the price of an electrical tape, but not so much that it becomes a decisive factor when choosing a protective and insulating material.
If, during use, some other drawbacks are found, then these are the shortcomings of the selected manufacturer.
The video below provides a visual comparison between heat shrink and electrical tape:
Where is the tube used HERE
Although the main purpose of the heat shrinkable tubing is to isolate the contacts, there are other ways to use it:
- Insulation of water and metal pipes from aggressive environments.
- Shrinkage on the butt of a metal or wooden power line support in order to protect against corrosion and decay of wood in the ground.
- Longitudinal sealing of cable bundles. Despite the external insulation, you can use a special tape that completely fills and also insulates the space between the conductors.
- To improve the ergonomics of sports equipment handles and construction tools through the use of grooved and ribbed tube surfaces.
- Converting simple tools, such as screwdrivers into dielectric ones, by insulating HERE.
- High temperature protection of the wire. There are products, the working temperature range of which varies from -65 ° C to + 260 ° C. This protection helps the wire to withstand such working conditions, even if there is a source of heat and fire nearby. These types of heat-shrinkable tubing are called PTFE or Teflon.
Heat shrink tubing specifications
First you need to know what the heat shrinkage for the wires is made of. It is made of polymer, thanks to which it can change and shrink. The size of the tube HERE can be reduced by half or even sixfold. The shrinkage ratio of the product ranges from 2: 1 to 6: 1.
Also, heat shrinks come with an adhesive layer, they are used when the connections need to be very securely sealed to protect against moisture and corrosion. An additional strength of the joints is achieved by the adhesive layer.
Heat-shrinkable tubes differ in the composition of the polymer. Some are made from PVC, elastomers, polyolefins, and various other materials. It is important that the product is resistant to fire, UV rays and good mechanical properties.
It is also important to talk about the dimensions of the heat-shrinkable tubes. All manufacturers put a designation on the product that will indicate its dimensions. The diameter is indicated both before and after shrinkage. The first numbers indicate the internal size before shrinkage, and the next ones indicate either the diameter or a factor due to which it can be calculated. The base or standard ratio is 2: 1. The maximum diameter of the HER tube is 120 mm, and the minimum size is 2 mm before shrinkage.
The most required heat shrinkage sizes are given in the table:
If you want to know how to choose a heat shrink tubing, we recommend watching the video provided below:
How to use heat shrink for wires
It remains to learn how to use the heat-shrinkable tube. So, the first thing to do is choose a suitable shrink size. If needed insulate wires, then it is necessary to cut a suitable piece that would overlap the insulated area, taking into account the fact that there will be a longitudinal shrinkage when heated. Usually it is up to 10%, this information is indicated by the manufacturer. On the surface, as well as on the cuts of the cut tube, there should be no damage or any burrs, because they can contribute to the rapid destruction of the material.
First, a tube HERE is pulled onto the cable, and then it is necessary to make a connection, over which a heat shrinkage will be put on. After connecting it, it is necessary to heat it with movements from one side to the other, so that a large longitudinal shrinkage does not turn out. This can also be done by heating from the middle of the joint to the edges. The second method is applicable for fairly long sections.
It should be remembered that it is impossible to warm up from both ends at the same time because an air bubble may remain, and this is very undesirable. Also, wrinkles may appear on the surface. The heat-shrinkable tube should be warmed up very carefully and evenly so as not to overheat in some place, because a bubble or surface rupture may appear.
Heating rate and temperature are determined by experiment. However, one should not rush, especially if there is no experience in this direction. Heating too quickly or at too high a temperature may damage the heat shrink.
The insulation process itself is not too complicated; if you wish, you can insulate the wire yourself. However, for a start, you can experiment on some piece of wire and make sure that everything is done correctly, and only after that you can take on the insulation of critical connections.
Finally, we recommend watching a video that clearly shows how to use a heat shrink tube for wires, using a hair dryer and a lighter for heating:
Now you know what a heat shrink tubing is, what it is for and how to use this device at home. We hope the information provided was informative and interesting for you!
You probably don't know:
- Which electrical tape is best for wiring
- How to protect the cable from mechanical damage
- What are the cable channels
