In electricity, the main thing is good contact and reliable insulation. Often the former depends on the latter. For insulation, you can use an insulating tape, but over time, the properties of the adhesive coating are lost and it can unwind, come off the cable under mechanical stress. Cambric is a tube made of PVC or rubber with good dielectric properties, most often white, beige or cream in color. From the article you will learn what are needed and what cambrices are, as well as how their types differ.
Content:
- What is cambric used for in electrics
- Shrink sleeves - shrink when heated
- How to use cambric
- Heat-resistant insulation - what is it
What is cambric used for in electrics
The main task is to insulate electrical cables, but people have come up with a lot of other uses, from the role of covers for screwdrivers and sewing machines, to use in fishing tackle. Twisted cable connections (already prohibited by PUE), soldering, welding, bolts, sleeves, as well as wires terminated with terminal lugs must be insulated. Most of these connections can be fitted with a cambric. For additional fixation and protection from moisture, the edges are fixed with electrical tape, and if one of the edges is free, it is heated with a lighter and squeezed with pliers.
In addition to insulating the connections, you can restore the insulating layer of the wire with a cambric, securing its edges with electrical tape so that it does not move. This type of insulation is suitable for AC and DC circuits up to 1000 V.
An additional function is marking. On a light cambric, a black felt-tip pen or marker is clearly visible. In any circuits, both power and signal and communication lines, at the ends of the cable near the terminal, put on a cambric with the designation wire markings.
Cambrices come in different sizes, they select products a couple of millimeters larger than the diameter of the cable, otherwise it will constantly fall off or will not fit. If you try to stretch it to the required diameter, it can burst, because this product has almost no stock in size. They are deprived of this disadvantage heat shrink tubing. In addition, PVC pipes dry out and crack from heating, and harden strongly in frost.
Shrink sleeves - shrink when heated
A heat-shrinkable tube or cambric, although it performs the same tasks, differs from the usual one both in the method of application and in the material from which it is made. These are usually polyethylene and other polymers.
Heat shrinkage can be halved when heated. This advantage allows the same tube size to be used for a much wider range of wire cross-sections. This gives a certain plus when used as insulation for various types of terminals and connections, because the shape of the terminal strip does not affect the quality of the wrapping. The shrink will shrink and follow any contours.
Heat shrinkage stretches well, up to 1.5-2 times of the original, but this must be done carefully, following the integrity of the surface. This way you can stretch the heat shrink on the wires and terminals if the size you want is not available.
The next difference from PVC tubes in heat shrinkage is in their appearance - they are sold in any color, including transparent completely or with color. This opens up even more convenience in marking, for example, the wires of one group are divided by color and signed by contacts. Like regular cambric, these products are inexpensive, but they can be found in every electrical or household goods store.
How to use cambric
Ideally, you need to seat with a stream of hot air. Any construction hair dryer is suitable for this. But more often it happens that it is not at hand or there is nothing to connect to.
The second option is a soldering iron. With the casing of the heating element, go over the surface of the tube and it will shrink. Sting doesn't need to do this for three reasons:
- Too high a temperature can melt the cambric.
- There are traces of carbon deposits from the sting.
- In order not to spoil the sting.
The third option is to use fire sources. It can be matches or a lighter. Keep the flame a couple of centimeters away from the heat shrinkage so as not to damage it, use quick and short strokes from all sides to achieve an even contraction of the insulating layer. For a quick effect, you can do it directly with a flame, then the movements should be even faster, and you should be more attentive. The disadvantage of this method is that traces of burning may remain on the cambric. Turbo lighters do not have this drawback, but the flame temperature is very high and it is easy to burn the pipe, so keep the flame away so that only streams of hot air fall on it.
The video example clearly shows how to use cambric for wires:
Heat-resistant insulation - what is it
Fiberglass tubing is a kind of high temperature resistant cambric, can tolerate -60 to 510 degrees without any problem. The fiberglass is impregnated with varnishes to improve its electrical insulating properties. Such options are often found in electric kettles, heaters, electric stoves and similar equipment. They are put on the supply wires and wires of internal connections near heating elements and spirals. Heat-resistant wire shields protect the contacts from temperature, thereby reducing the likelihood of corrosion and loosening, as well as melting of the insulation. They are more expensive than others, so the use everywhere does not make sense.
Alternative application. DIYers and radio amateurs use heat-resistant fiberglass tubes for insulation homemade soldering irons, burners and similar devices. For example, they are put on a sting under a spiral so that inter-turn closures do not occur. In the process of work, the varnish burns, after which it continues to perform its tasks and does not burn out.
Wire shims are sometimes better suited for insulating conductors and joints than insulating tape. Their price and ease of use increase the quality, safety and durability of electrical devices and circuits. Of course, this is an essential consumable for an electrician, it looks more aesthetically pleasing than electrical tape, and more reliable in some cases, but it is better to use both in pairs.
Finally, we recommend watching a video that shows how cambrics are used to mark wires:
It will be helpful to read:
- Which electrical tape is best for wiring
- Color coding of wires
- How to use a multimeter
- How to insulate wires
