Which electrical tape is better?

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Who is older probably remembers that 15-20 years ago the word “Insulating tape” was strongly associated with a roll of blue tape made of tough polyvinyl chloride fabric, which after winding always peeled off and unwound sooner or later. Well, what came to mind second? Of course, the so-called “Cotton insulating tape”. Unpresentable in appearance, made of gray-black cotton rag with protruding threads, wound into an uneven roll, which emitted a sharp smell of insulating resin with which this rag was impregnated. Those who are even older (especially those who played hockey in the schoolyard in winter) remember that this tape was very popular in the USSR for protective wrapping of hockey sticks. Many considered it frost-resistant compared to PVC insulating tape.

Time passed and technical progress moved forward. The USSR collapsed and our country embarked on the path of capitalism. Western companies began to enter the undeveloped market in Russia, opening their representative offices and introducing Russians to their various products. As for our topic, the technology of splicing power cables and communication cables also did not go unnoticed. New solutions and new insulating materials appeared here as well. But despite such expansion, in our country, on the market of consumable electrical insulating materials, the same two types of insulating tape still dominate: cotton tape (CT) with electrical insulating impregnation and polyvinyl chloride (PVC) electrical insulating tape with an adhesive layer. They can be bought in all well-known specialized stores of engineering systems, in all marketplace stores, at gas stations, auto parts stores, etc.

Yes, over the past 15-20 years, these two products have begun to look more decent and neater. And yes, they have become higher quality. But what about other types of insulating tapes on the electrical market? What are their differences and what are their advantages? And why are only these two types of insulating tape so popular in the Russian Federation? Are they the best solutions for electrical insulation? Let’s sort out all these questions in our review article.

PVC insulating tape or cotton insulating tape? Which insulating tape is better suited for professional use?

Let’s first look at this comparison, which is often covered on the internet and concerns these two popular consumables. In my opinion, as a specialist with 25 years of experience in promoting insulating materials to the electrical market, this is simply a one-sided formulation of the issue.

Let’s say, if a professional electrician insulates stationary current-carrying parts of electrical installations with a voltage class up to 1 kV, having a smooth and even surface, in a dry and clean room with no aggressive chemical influences, where the constant air temperature is +22°C, where the relative humidity is not more than 60%, where there is no direct sunlight, then either of these insulating tapes will perform its direct purpose well under these conditions. Well, only if these tapes are not older than 10 years and if they are of acceptable quality. However, if electrical installation work is carried out even simply OUTDOORS, it will be simply impossible to ensure such a combination of conditions during installation and further operation of the equipment. I am not even talking about any special operating conditions for electrical equipment. Dust, dirt, soot, technical oils, moisture, salt, precipitation, low and high temperatures, destructive ultraviolet, vibration, abrasive effects – these are only part of those aggressive conditions in which it is often necessary to insulate current-carrying parts of electrical equipment. Will a professional electrician, using PVC tape or cotton tape for these purposes under such conditions, be able to ensure reliable insulation of wire and electric cable contacts? Will it be possible to safely operate the electrical equipment connected by them in the future?

What types of insulating tapes are there? How do they differ? Where should they be used and what can they do?

Cotton insulating tape

In my opinion, cotton insulating tape today can be classified as one of those insulation solutions used by adherents of the “old school” of electrical installation or simply by fans of “retro”. Cotton insulating tape is objectively inferior in its insulating characteristics to the simplest modern PVC insulating tape from China and has a number of disadvantages, the main one being its hygroscopicity. Constant contact with water reduces the resistance of the tape, significantly degrading its insulating properties, and over time turns COTTON INSULATING TAPE into just COTTON TAPE. Whoever likes it can use cotton insulating tape for bundling insulated wiring, bandaging something, or for other applications not related to electrical insulation. For example, for wrapping hockey sticks for yard games. Let us leave cotton insulating tape out of this article and move on to more modern solutions.

PVC insulating tape

This is perhaps the most popular type of insulating tape, which truly surpasses cotton insulating tape in its characteristics and properties. And it may be more preferable for so-called “Professional use”. But where did this phrase even come from: “Insulating tape for professional use”?! Where did this title come from, which they try to bestow on any PVC insulating tape from a “Household goods” store? Let me give a brief historical digression. In 1946, one American company released the world’s first vinyl tape with an adhesive layer, designed for restoring electrical insulation. This tape quickly gained popularity in construction, power grid maintenance, and the automotive industry. According to statistical studies, in 2008, sales of PVC tapes from this company accounted for 62% of the entire PVC tape market in the United States. Its market share far outpaced its competitors. So, in order to properly position its product, this company in the 1970s divided its range of vinyl insulating tapes into three groups:

• PREMIUM (or PROFESSIONAL GRADE);
• GENERAL USE (or MEDIUM GRADE);
• SUB-GENERAL USE (or ECONOMY).

PVC insulating tapes from each of these three groups differed from each other in their characteristics, packaging, and price. They were intended to meet the needs of different customers. That is, the customer was given a choice: buy ECONOMY or PREMIUM. Pay less or more. Purchase a product with modest but sufficient characteristics for him, or purchase a high-quality product for use in harsh conditions. What are their differences? First of all, in the composition of the PVC backing and the composition of the adhesive layer. PVC tapes of the GENERAL USE class have a much more elastic PVC backing due to certain plasticizers in its composition and a higher quality adhesive layer than tapes of the ECONOMY class. Their backing thickness is at least 0.18 mm, and they can be used normally at slightly sub-zero temperatures. Due to the higher elasticity of their PVC backing, they adhere well to relatively uneven surfaces, conforming well even at temperatures down to -10°C. When exposed to temperatures up to +80°C, their adhesive is guaranteed not to flow, so they do not slip or peel off the surface. PVC tapes of the PREMIUM or PROFESSIONAL GRADE class have the same properties as GENERAL USE tapes, but due to the high-quality materials from which they are made, they have even higher characteristics. They can be easily used at -20°C – they will maintain high adhesion and elasticity (not just the ability to stretch, but also the ability to quickly return to their original state). As for heating, they can operate continuously without losing their properties at temperatures above +100°C. No ECONOMY class PVC tape can work under such conditions (anyone who has had experience working with a PVC tape costing 100 rubles even in light frost knows how this PVC tape becomes stiff, tears, and has poor adhesion). Many PROFESSIONAL GRADE PVC tapes have a vinyl backing thickness of 0.25 mm, widths of 25 mm, 38 mm, and 50 mm, and a roll length of up to 33 meters. Such tapes are typically intended for anti-corrosion protection or repair of damage to the outer sheaths of heavy cables that are subjected to pulling and abrasive impact. If we follow the properties of PVC tapes according to this company’s classification, then the vast majority of those tapes currently widely represented on the electrical market of the Russian Federation, by their characteristics, can be attributed rather to the ECONOMY group. As a rule, these are rolls of size 19mm x 20m, 15mm x 20m, 15mm x 10m and even less in winding, wrapped in cellophane film. The thickness of these tapes is from 0.15 mm to 0.18 mm. Their price is within 150 rubles. On their labels you can see amusing inscriptions designed for the average consumer. Such as “NON-FLAMMABLE”, “6000 Volts”, “Highest grade”, “EXTRA STRONG”, “HEAVY DUTY”, “Elongation 200%”, “UV” (ultraviolet resistant), “Insulating tape for professional use”, and the like. In fact, these are ordinary PVC tapes with modest characteristics for household use. For example, for insulating internal electrical wiring (0.4 kV), in dry and heated rooms, where there are no special external aggressive influences. This can be easily verified in practice by comparing all PVC tapes available for sale, with flashy advertising inscriptions on the labels, with the PVC tapes of the above-mentioned well-known company. Where do I get this information and why do I make such a claim? I simply worked for that company for 18 years until it left the Russian market in 2022 due to sanctions imposed against our country. I know from practice what PREMIUM or PROFESSIONAL GRADE PVC insulating tape really is.

Yes, and returning to the origin of the title “Insulating tape for professional use” – this is simply a translation of the words “PROFESSIONAL GRADE”, which numerous would-be marketers took from the packaging of that American company’s products and began to use it on the labels of their tapes, without fully understanding its meaning.

Summarizing PVC tapes:

1. You should not use any PVC tape for insulating current-carrying parts of electrical installations above 1 kV. For these purposes, there are other types of insulating tapes, which we will discuss further.
2. For primary insulation up to 1 kV, the electrical strength of the PVC backing will be quite sufficient for any PVC tape. This is a self-evident property of such a material as PVC.
3. Two main properties of high-quality PVC tape: good elasticity and an adhesive layer that is stable over a wide temperature range. The elasticity of PVC tape allows it to tightly compress the current-carrying element being insulated. When the tape is wound with tension, its backing tends to return to its original length – that is, a shrinkage effect occurs, similar to that of an elastomeric tube. This forms a sealed layer, protected from the penetration of dust and moisture under the tape, plus decent mechanical protection. However, if the PVC tape has mediocre elasticity, we cannot wind it tightly, which reduces this shrinkage effect to zero. In addition, even if the PVC backing of the tape has good elasticity, but the adhesive layer is weak or unstable (its adhesion decreases at sub-zero temperatures, and at temperatures above +50°C the adhesive begins to soften and flow), then the shrinkage effect will also not be achieved. Such an adhesive layer will not be able to hold the tape wound under tension. Its backing will tend to return to its original length and, instead of tight shrinkage, the tape will simply unwind and slip off the surface on which it is wound.
4. Not all PVC tape that is widely sold on marketplaces and DIY stores is suitable for professional use. Almost all of it is tape for household use, despite all the loud claims written on its labels. Yes, it is absolutely suitable for insulating internal electrical wiring (0.4 kV) in dry rooms, where it will not be subject to any external aggressive influences. In harsher operating conditions, you should not expect miracles from it.
5. If a manufacturer claims that its PVC tape is for professional use, it must have excellent elasticity and tackiness both at +22°C and at minus 10-20°C. These two properties should not deteriorate when installation is carried out below 0°.
6. I want to mention separately such a property as UV resistance. All inexpensive PVC tapes used for insulation or as protective sheaths outdoors should be only black. Any NON-BLACK PVC tapes are primarily intended for marking indoors. It is very strange to see on the labels of PVC tapes in yellow, green, red, and other NON-BLACK colors, sold at a price of 80 rubles in well-known retail chains, a “UV” pictogram, or a “sun” pictogram, or the inscription “UV Resistant”. All inexpensive colored PVC tapes degrade quite quickly under sunlight.

So, from popular PVC tapes we smoothly move on to other types of modern insulating tapes, which can rightly be classified as tapes for professional use. In their work, they are used by professional electrical fitters and cable splicers who work in the power grids of mining and coal enterprises, drilling companies, and other industrial facilities where the operating conditions of electrical equipment are quite harsh. These tapes are not as well known to the general public as the familiar PVC tapes, so you are unlikely to find them in household and construction stores, as well as in DIY chains. The tapes that will be discussed below can mainly be purchased from organizations that specialize in supplying electrical insulating materials for the needs of industrial enterprises in certain industries.

Rubber self-vulcanizing tapes

Unlike PVC tape, these tapes do not have an adhesive layer. To achieve the self-vulcanization effect, when winding these tapes, they should be stretched so that their width becomes 1/2 of the original. Self-vulcanizing tapes come with an ethylene-propylene rubber backing and a silicone rubber backing. Both tapes, when wound in layers, self-vulcanize, forming a continuous layer of insulation containing no air voids, which significantly increases the electrical strength of this insulation. That is, in this case, the winding literally turns into a full-fledged rubber tube, which with great radial pressure fits tightly to the surface on which it is wound.

This effect is called cold vulcanization and occurs immediately after winding. Unlike PVC tape, this tape will never unstick or unwind. This tape does not need to be heated with a hairdryer or gas torch. It does not need to be baked in an electric vulcanizer, like raw rubber. Rubber self-vulcanizing tape with an ethylene-propylene rubber backing, such as AVB MINING TAPE type 23, has excellent dielectric characteristics and can be used for restoring insulation on both low-voltage cables and medium-voltage cables up to 35 kV. It is compatible with all solid dielectrics used in cable insulation: low-density and high-density polyethylene, cross-linked polyethylene, polyvinyl chloride, ethylene-propylene rubber, etc. This tape can operate continuously at temperatures up to +90°C, fully maintaining its characteristics. In addition, it is resistant to short-term temperature rises up to +130°C and to corona discharge.
Where is this tape typically used? Like PVC tape, it is universal in its application. However, its main purpose is to form the primary electrical insulation when connecting wires and cables operating at voltages from 600 V to 35 kV, made of solid dielectrics. This type of tape is included in many resin-filled cable joints and cold-shrink joints for low and medium voltage. It can also be used to insulate low-voltage and high-voltage busbars.
Among other things, this tape provides good sealing of any electrical connections. Another rubber self-vulcanizing tape (with a silicone rubber backing) can be classified as a high-temperature insulating tape resistant to electric arcs and tracking on the insulation. For example, AVB MINING TAPE type 70 has high electrical strength, can be operated continuously at temperatures up to +180°C, and has excellent resistance to ozone. In addition, this tape can operate at extremely low temperatures, has excellent hydrophobicity, and vulcanizes instantly upon winding.
Like the rubber self-vulcanizing tape with an ethylene-propylene rubber backing, this tape is compatible with all synthetic materials from which the sheaths and insulation of modern cables are made. Where is it most rational to use this tape? Virtually everywhere where reliable insulation is required. But it is especially in demand as primary insulation in conditions where temperatures reach +180°C (for example, in repairing sheaths and insulation of silicone rubber cables operating at high temperatures).

This tape is also in demand in the other extreme – when primary insulation is required for operation at very low temperatures down to minus 60°C. In addition, this tape has proven itself well in insulating the terminals of medium-voltage cable terminations to protect against electric arc and tracking on the termination insulation.

Soft mastic tapes

Like the rubber self-vulcanizing tapes we just examined, insulating mastics do not have an adhesive layer. And also, like rubber self-vulcanizing tapes, these tapes will never unstick or unwind, unlike any PVC tape. These tapes do not need to be heated or baked. Their backing is made of non-corrosive synthetic rubber, which, when stretched, instantly vulcanizes with itself, and when tightly wound onto a metal or polymer surface, creates adhesion with them comparable to the adhesion of hot-melt adhesive, as when shrinking a heat-shrinkable polyolefin product.

Mastic tape, such as AVB MINING TAPE type Polyfill 38, which is in our range, can be compared to a soft, ready-to-use electrical insulating compound. Nevertheless, it is still a tape, as it is made and supplied in the form of a tape.
In which cases is mastic tape indispensable? For example, when reliable insulation is required on current-carrying elements of irregular shape. With it, you can create insulation, smoothing out all corners and protruding parts of the conductor. At the same time, you will immediately reliably seal this conductor. Then, on top of this mastic tape, over the insulation of the correct shape you have created, for mechanical protection of the mastic, tightly wind PVC tape. On a smooth soft surface, PVC tape will lie just perfectly. In general, the main applications of mastic are as follows:

• Insulation of connections up to 600V;
• Connecting cables and filling large irregularities and voids in low-voltage connections to create a smooth surface for subsequent winding with insulating tape;
• Smoothing of irregularly shaped high-voltage connections;
• Smoothing of busbar irregularities;
• Creating a plug in joints when injecting compounds under pressure;
• Sealing the grounding wire brought out from high-voltage connection joints;
• Sealing of multi-core cable connections;
• Sealing of electrical connectors.

Mastic tape has excellent electrical characteristics and high resistance to aging. It is pliable when molded with slight finger pressure even at temperatures below 0°C. Neither the tape itself nor its components cause corrosion of copper. The tape has adhesion to most types of synthetic cable insulation, as well as to all other tapes. And it does not lose its properties at temperatures up to +80°C.

Double-layer mastic tapes

These insulating tapes, in terms of their operational reliability, can easily compete with such solutions as thick-walled heat-shrinkable tubes with an adhesive layer or repair heat-shrinkable sleeves. At the same time, if we talk about the simplicity and versatility of using these double-layer mastic tapes, they are much more convenient than the above-mentioned heat-shrinkable materials. These tapes are wide (up to 50 mm) double-layer elastic tapes, the top layer of which is made either of thick vinyl (vinyl-mastic insulating tape) or of ethylene-propylene rubber (rubber-mastic insulating tape), and the bottom layer is made of very sticky, heat-resistant mastic.

Double-layer mastic tapes, such as AVB MINING TAPE type 2228, are specially designed for fast insulation and mechanical protection of copper or aluminum conductors, as well as for sealing electrical connections up to 1 kV. They are rated for operating temperatures of +90°C and short-term exposure up to +130°C.

Why are they more convenient and easier to work with, but no less reliable, than thick-walled heat-shrinkable tubes with an adhesive layer or repair heat-shrinkable sleeves?

1. They do not need to be heated to properly and reliably shrink the insulating material onto the conductor;
2. They do not need to be threaded through the entire cable to the repair site, like, for example, a heat-shrinkable tube;
3. You are not tied to a specific size, as is the case with selecting the diameter of a heat-shrinkable tube or sleeve. And you can use this tape to create insulation or a sheath both on cables with large cross-sections and on very thin wires with a cross-section of 1 or 0.5 mm². Simply cut off as much material as you need for the operation;
4. As a product, these tapes, unlike heat-shrink, are much more versatile and have many other useful applications related to sealing, mechanical protection, and corrosion protection.

Well, the main examples of applications for double-layer mastic tapes are as follows:

• Electrical insulation of busbars up to 1000 V;
• Electrical insulation of cable connections up to 1000 V;
• Sealing of electrical connections up to 1000 V;
• Corrosion protection of bolted busbar connections up to 35 kV;
• Repair of damage to solid sheaths of low-voltage and high-voltage cables;
• Insulation of cable entries of electric motors up to 1 kV.

What else can be said about these tapes? They have excellent resistance to moisture and ultraviolet radiation. They provide excellent performance when applied to uneven surfaces. They easily withstand operation in the ground or underwater, as well as atmospheric influences when used outdoors. These tapes are flame-retardant and have excellent adhesive characteristics for use on copper or aluminum busbars, connectors, couplers, as well as power cable sheaths. What more could you want from a tape for “professional use”?

Insulating kits

The effectiveness of using the above-mentioned tapes can be further increased if they are applied as comprehensive solutions for various tasks in the field of electrical insulation and sealing.
Suppose you need to seal two joined cable connectors of irregular shape, the connection of which must operate in dust, then under atmospheric precipitation, with constant vibration, sometimes heating up to +60°C. One PVC tape is unlikely to be able to provide long-term sealing and protection of this connection. But if you:

1. first apply mastic tape winding onto the connection of these connectors (smoothing sharp corners and sealing);
2. on top of the mastic, make a tight winding of self-vulcanizing tape made of ethylene-propylene rubber (it will create radial pressure on the mastic to enhance the effect of cold vulcanization and tightness);
3. for mechanical protection and UV protection, apply two layers of good black PVC tape, such as AVB MINING TAPE type 22 or AVB MINING TAPE type 33 +,

..then I assure you that having done these simple manipulations with the sequential application of these insulating tapes, you will not have to worry about the reliability of such a connection.
Another example using the same types of tapes: the outer sheath of an operating power cable is damaged and its sealing is broken. It must be disconnected and repaired. This can be done in different ways:

• completely cutting out the damaged section and making a cable insert with two connecting joints, but this is quite labor-intensive and expensive;
• you can repair the sheath using a heat-shrinkable sleeve, but here you need a specific sleeve size, a gas cylinder with a torch, in certain conditions, the registration of hot work (where there are restrictions on the use of open flames), again the issue of the cost of the sleeve itself;
• repair the section of the outer sheath using an insulating repair kit, such as AVB MINING KIT type KM-012.

To do this, you need:

1. Clean the sheath damage site from dirt and dust;
2. Fill (putty) it with mastic tape (the effect of a sealant or putty);
3. On top of the mastic, make a tight winding of self-vulcanizing tape made of ethylene-propylene rubber (radial pressure on the mastic to enhance the effect of cold vulcanization and sealing of the sheath);
4. On top of the self-vulcanizing rubber tape, make a winding of two or three layers with half-overlap of thick vinyl tape.

And here the reliability will be no worse than from repair with a heat-shrinkable sleeve with an adhesive layer, and the repair itself is both simpler and cheaper.
There are many such examples with combinations of options for electrical insulation and sealing. Everything depends on the task and common sense in solving it.

Is insulating tape just a mass consumable, not worth spending time on choosing?

Over a quarter century of my communication with many different people (from an electrical fitter to a chief power engineer, and from an ordinary procurement specialist to the director of the logistics supply department), their attitude toward insulating tape can be summed up in three phrases:

• All insulating tape is the same;
• Insulating tape is a cheap consumable that does not deserve special attention;
• Insulating tape is universal and necessary for the operation of electrical equipment, but it cannot be called a reliable solution for electrical insulation.

It turns out that insulating tape, as a product whose main purpose is to provide electrical insulation, is not a reliable solution for electrical insulation? Agree, that sounds strange. But why is there such a biased attitude toward insulating tape as an insulating product, compared, for example, to the same heat-shrinkable tubes? I believe this entrenched opinion comes from the past, when those very PVC and cotton insulating tapes that I mentioned at the beginning of this article were sold in hardware stores. They were also purchased for their needs by suppliers of industrial enterprises, construction organizations, and municipal services. It was always so simple and cheap that the unit of measurement for insulating tapes was “kilograms” rather than “pieces”, and the quality, despite GOST 16214-86, left much to be desired. All of this created for insulating tape the image of a simple and cheap product with low reliability, which has stuck with it to this day. And the answer to the question “Why are PVC tapes and cotton tapes the most popular solutions among consumable insulating materials in the Russian Federation” is very simple – they are simply consumer goods. By international definition, one could say they are FMCG (Fast Moving Consumer Goods), and in the Russian vernacular – “Shirpotreb” (mass consumer goods). They are inexpensive and understandable to a wide range of buyers. Just like a light bulb, soap, or toilet paper. And this means that they are by definition always popular. But let us finally move away from these established opinions. Believe me, today they are as much a stereotype as, for example, the idea that all residents of Russia drink only vodka and walk down the street with balalaikas. And let us look at insulating tapes differently. Not only as a “mass consumer goods”, but as serious and reliable operational solutions.

Conclusions

If we do not go deep into the specifics of applications, then in this article we have covered in simple language the main types of insulating tapes used by, among others, professional cable splicers and electricians. So which insulating tape is better? Perhaps all of them are good in their own way, if they are used where their properties can solve the required task. A professional electrician has different tools for different tasks. He is unlikely to go to work with only one pair of pliers in his pocket. So why should he use only “mass consumer goods” in the field of insulating materials? Having all the above-mentioned insulating tapes in his arsenal, a specialist expands his capabilities and the level of electrical installation work, and the conditions in which he can carry them out are significantly broadened. After all, all these tapes, depending on the specific task, can be used not only individually, but also comprehensively, combining their types and strengths.

Before using any particular type of insulating tape, it is necessary to objectively assess not only the properties and capabilities it possesses, but also the conditions in which it will be operated. And of course, it is always better to underestimate the properties of the tape than the conditions in which it may be applied.

All the described modern insulating tapes, as well as universal repair kits and kits for repair, termination, jointing, and branching of cables based on these materials, you can find in the catalogue on our website. You can also submit a request by writing to us at info@avbmining.com or ask questions if you need a consultation.