How and when to use insulating tape

How can you use insulating tape? How should you apply it for proper insulation? These rolls of colourful tape undoubtedly appear in the top five tools used daily by electricians, together with screwdrivers, pliers, and scissors.

They are, therefore, pretty common-use tools, which are rarely missing in household toolboxes of people who are at least a little bit of manual skill.

Nevertheless, many people do not know how to use insulating tape correctly, and this is an issue: using insulating tape incorrectly can in fact lead to dangerous consequences, or at least the malfunction of an electrical set-up or an electrical device.

So, let’s have a look at how to use insulating tape to insulate electrical wires without any mistakes.

What is insulating tape?

Insulating tape is, in effect, an adhesive tape. It is in fact a roll of tape that is adhesive on one side and smooth on the other.

To distinguish insulating tape from the simple tape, as well as other adhesives such as paper tape or American duct tape, is its ability to isolate objects which have current passing through them.

It is therefore not surprising that insulation tape is made of materials with an extremely low conductivity, such as PVC. Thanks to these materials, it is therefore possible to insulate electrical wires using only a minimum amount of thickness, corresponding to a few tenths of a millimetre.

There are several types of insulating tape on the market, as well as, of course, within our very own professional adhesive tape online store: the best ones are those made with high quality PVC and which are self-extinguishing.

They can also differ in width and length (insulating tape is, generally speaking 15, 20 or 25 mm (0.5, 0.7, 0.9 in) wide, with individual rolls 10 to 25 m (32.8, 82 ft long).

Insulating tape colours can differ too, to facilitate the work of electricians who need to distinguish different electrical wires between each other (because of this, there are sets with 9 different colours, which typically include black, white, red, grey, yellow, green, blue, yellow-green, and brown).

When should you use electrical tape?

When should you use insulating tape? Sometimes insulating tape can be useful for quick home repairs.

For example, you may want to change the hair dryer’s power plug type from European to American: in this case, you could cut the wire near the plug, peel off the two electrical wires and, using electrical tape, connect them to an American plug.

Or, you might find yourself having to extend an electrical wire without using clamps: in that case, too, insulating tape will be useful.

In general, insulating tape is useful whenever you need to create a splice between electrical wires without being able or willing to use clamps; usually, for example, insulating tape is better than clamps whenever you have to deal with smaller diameter rigid cables, even more so if the alternative is direct fastening clamps.

Having outlined how to use insulating tape, let’s have a look at how to use it properly.

How can you use insulating tape to insulate electrical wires?

How can you use insulating tape to insulate electrical wires? Let’s assume you need to simply connect 2 electrical cables. You will need to get everything ready, and then go ahead and strip off the 2 copper wires on both sides.

This operation should be done using appropriate electrician scissors, which make it possible for you to gently remove the sheath protecting the copper wires, without cutting the metal filaments themselves. Once the 4 copper wires are visible (2 on one side and two on the other) you can create the splice by braiding the red wire with the other red, and the blue with the other blue (as an example).

At this point you can start using the insulating tape, with due caution.

If the cable isn’t too big, use insulating tape with a reduced width (for example, 15 mm, i.e., 0.5 in) while for larger cables you will need to use insulating tape with greater width. The cables must also be perfectly clean, to avoid compromising the insulating tape’s adhesive’s grip.

How can you begin taping the electrical wires? Well, it all starts with the act of lifting one side of the electrical tape, pulling out about 2 cm (0.7 in) of tape. You will then be able to place the strip of tape on one side of the cable section to be taped, making it adhere well through slight pressure of your thumb and index finger.

Now you can proceed with the actual taping, unrolling a few centimetres of tape and then wrap it around the electrical wire: the first layer must be totally overlapped.

After this first layer, you can start moving slowly towards the other end of the stretch of cable to need to mask, one layer after the other. You should always remember that each layer must overlap about halfway with the previous one, always keeping the electrical tape tightly stretched.

Once the whole area is covered, it will be possible to make the last wrap-around, once again overlapping, like the initial one, then cutting off the excess electrical tape.