A Guide to Electrical Insulation Tape
What is electrical insulation tape?
Electrical insulation tape is used in both residential and commercial environments to insulate and protect cables and wires that conduct electricity. This could be a range of applications such as doorbell wires or outdoor lighting on top of windows during Christmas time. Also known as insulating tape, it is available in a range of widths and thickness dimensions, as well as materials from PVC to rubber.
It is manufactured in different colours to indicate various uses and properties. For an electrical insulation tape to be effective, it must work as an insulator to protect against electricity, be flexible and easy to use for a range of cables and wires, and provide a high level of heat and fire resistance.
Types of electrical insulation tape
There are 4 types of tape and each one is best suited for different purposes. Here is a round-up of crucial information that you should know.
1. Varnished cambric
Coated with electrical insulating varnish and primed with oil, varnished cambric is produced from woven cotton fabric. The combination of oil and varnish helps to protect electrical currents without any damage being caused by energy travelling through the wire. Varnished cambric is well-suited for covering corners, rough edges and bolts. It is particularly useful for cars and spaces in your home where you require puncture resistance or mechanical protection.
2. Rubber
This electrical insulation tape is usually non-adhesive. For it to be effective, you should stretch the rubber tape and wrap it tightly around the wires and cables to stamp out voids in crucial areas. Rubber tape is primarily used for terminating and splicing cables and wires which are rated up to 69 kilovolts (KV). It also provides a certain level of water resistance.
3. Mastic
Manufactured with either no backing, rubber backing or vinyl backing, mastic electrical insulation tape is versatile and a favourite go-to for electricians because of its flexibility around odd-shaped areas and tight spaces. Generally, this type of tape is used to insulate synthetic cable jackets, rubbers and metals - it also creates resistance to UV and a moisture seal which makes it a viable option for outdoor use.
4. Vinyl (PVC)
Made with an abrasion-resistant PVC backing, vinyl electrical insulation tape is the most common type for home use. It is flexible, and long-lasting, and is a great solution for insulating electrical connections and wires during electrical tapping. Although its main purpose is to work as an electrical connection insulator, it also provides protection against moisture and is an effective tool for repairing small cuts and nicks.
Electrical insulation tape colours
You will find that electrical insulation tape is primarily sold in black. However, it is also available in various colours, and each colour signifies a different voltage or phase level. Below is a guide on the definition of each tape colour.
| Electric insulation tape colour | Definition |
| Grey insulation tape | Although it is not overly used in the UK, grey electrical insulation tape is generally used to signal low voltage/phase C. |
| Black insulation tape | Electricians will mostly use black tape for the insulation of connections and wires. |
| Red insulation tape | Primarily used as a low voltage tape in the UK. Its definition is different around the world - in the US, red insulation tape indicates low voltage/phase B. |
| White insulation tape | Often used for various household tasks that involve white cords and wires for external applications. |
| Yellow insulation tape | Used for low voltage/phase B in the UK. Internationally, yellow tape signals sheath/110V site wiring’. But in the US, it means high voltage/phase C. |
| Blue insulation tape | Widely used in the UK and indicates low voltage/phase C. This is also the same for the US. Internationally, blue insulation tape means low voltage or neutral sheath/230V. |
| Brown insulation tape | Not often used in the UK. But internationally, it is recognised as low voltage/phase A. In the US, it is high voltage/phase A. |
| Green insulation tape | Indicates ‘earth’ in the UK. In the US, it would indicate ‘earth ground’. A yellow and green striped tape would signify ‘earth’ internationally and ‘isolated ground’ in the US. |
Advantages of electrical insulation tape
Regardless of which colour tape you use for a project, electrical insulation tape is manufactured to provide strength and protection. Here are the main advantages to think about.
Stretchy and flexible
Designed to elongate and stretch before breaking, electrical insulation tape is different to many adhesive tapes. Once wrapped around a cable or wire, the tape will shrink back to its original state to fit around it tightly. This allows the tape to block out any dust or moisture. But you should be aware of low-quality electrical insulation tape, which does not stretch as much and will create a less effective moisture and dust barrier.
Strong protection
Although it may look simple, electrical insulation tape is an important tool. It stops a current from travelling between nearby wires and stops any electrical shorts or - in extreme circumstances - fires. Also, it is generally heat-resistant and fireproof which is crucial when coming into contact with flammable objects and materials, such as timber-framed stud walls.
Multi-purpose tape
Even for very small or non-electrical jobs, electrical insulation tape is handy for a variety of tasks, such as electrical cord repairs. When using the tape, be sure to only use it if the wires are not frayed inside of the covering - it should be used before major damage such as a covering split has occurred. Plus, electrical insulation tape can be used for household and other jobs, such as protecting sports equipment from moisture build-up, repairing tent holes when camping, and preventing splinters and slippage on drumsticks.
Disadvantages of electrical insulation tape
Before you start to use tape for any electrical jobs around your home, you should be aware of the possible downsides that could arise.
Fire damage
Although a rare disadvantage, electrical insulation tape can become flammable if it gets hot enough, anywhere above 80°C. If the tape is used correctly, the probability of combustion is very low, but this also depends on where the tape will be used. Some electrical insulation tapes are more resistant to heat than others. For example, silicone rubber tape can withstand temperatures up to 200°C, whereas polyester electrical insulation tape can work to temperatures up to 130°C.
Not waterproof
Its elasticity means it can easily be wrapped around equipment such as garden hoses, but it is important to note that the tape is not waterproof. The adhesive degrades when the tape gets wet and the seal would lose its shape under pressure. Also, its performance would greatly be compromised if exposed to large amounts of liquid.
Short lifespan
On average, electrical insulation tape has a lifespan of 5 years. This means that during this short timeframe, the tape will lose a lot of its qualities such as its heat and moisture-resistant levels. It is also not a permanent solution for repair work - particularly with rubber-based electrical tape, the elasticity will decrease overtime. Once you buy the tape, be sure to use it promptly to avoid compromising its performance.
Can you put electrical insulation tape on cut wires?
An important factor to note is not to use electrical insulation tape to cover major damage, such as anything larger than a small cut or abrasion. Simply covering the damage could lead to electric shocks. In this circumstance, the wires will need to be replaced. Should you cut a wire and leave the end of it exposed, this could lead to a serious accident if you or someone else were to touch it with tools or bare hands. Wearing insulated gloves will help you to work with live wires.
Tips on how to use electrical insulation tape
Health and safety should be your top priority when working with electrical wires and cables. Here are 3 tips to keep in mind when applying electrical insulation tape.
1. Avoid outdoor use
Because it is not completely waterproof, you should avoid using the tape for outdoor applications. If you need to use tape for any reason, try the mastic type. Despite some resistance to moisture and water, it is best to use either an adhesive or waterproof sealant as a replacement for any outdoor electrical jobs.
2. Do not double tape
Electrical insulation tape is primarily used to protect cables and wires from any damage. It might be tempting to cover the tape with an additional layer, but this becomes unsafe. Especially when covering pipework with tape, if you choose to add another layer, the tape will turn hot and put you at risk of a flammable situation.
3. Properly wrap the tape
Since it will usually be used around more circular objects like pipes and wires, there needs to be a little bit of technique applied to wrapping the tape. You should be able to pull on the tape while wrapping it - this will ensure a reliable and secure hold.
Can you use duct tape instead of electrical insulation tape?
As an alternative, the simple answer is no - you should not use duct tape as a replacement. Despite its multi-purpose properties, duct tape is unsafe to use for electrical jobs because it has not been manufactured to provide protection from live wire currents. Below are 3 key differences you should know about.
- Created from PVC or stretchy vinyl material, electrical insulation tape is structured to provide improved insulation against live currents. Also, duct tape could become flammable from the heat of the live currents.
- Using duct tape as protection over exposed wires is better than nothing, but its lack of electrical insulation properties mean it is not suitable for use as an alternative tape.
- Although it is technically not waterproof, duct tape provides a certain level of moisture resistance. But compared to most electrical tapes, duct tape is not as durable and will weaken in adverse conditions.
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