Do you know what the heat shrink tubing is?
Did you see it in the electrical panels before?
Did you ask yourself how to order heat-shrink tubing for your cables and conductors?
Have you ever asked yourself how you can install it On-site?
All the above questions and more about heat shrink tubing are answered in this article.
At the beginning, I want to remind you that any building will definitely have electrical outlets.
These outlets can be found in many types, like electrical normal power sockets, emergency sockets, lighting outlets, …etc.
And to power all these outlets, you need an electrical panel.
This electrical panel will be fed by one of two methods: either a busway (usually via a tap-off) or power cables, which is the most common method in most projects.
These cables will be for sure multi-core to feed the different phases of the panel.
The multi-core cables we can find in one of the following forms:
A- Double cores or two cores cable, plus an additional single core. The core means conductor, and each conductor will have its insulation, either PVC, or XLPE, or LSHF, …etc.
In this case, the cable’s manufacturer is combining the two cores into a single outer sheath.
We are using this cable to feed the single-phase panels and loads. The two cores we use to supply the phase and neutral are separate, while the single-core we use for earthing the panel.
B- Three-core cable: We will use this cable in the above scenario, but in this case, the manufacturer combines the three cores into a single outer sheath.
C- Four Core Cable, we are using this cable to feed the three phases of panels and loads.
Three of the cable’s conductors supply the three phases of the panel/load, while the fourth core/conductor serves as the neutral.
So if you cut a section of this cable, you will see four colors usually, these colors will be Red, Yellow, Blue, Black, or Brown, Black, Grey, Blue, or as per the standards of your country.
To provide an earth for the panel or the load, we provide an additional core or conductor.
Notes:
For multi-core cables, we have two main types based on the neutral’s cross-sectional area. The first one is when the neutral cross-sectional area equals the phase conductors’ cross-sectional area in the first type.
In the other type, the neutral’s cross-sectional area will be almost half the phase size, and in this case, we will call the cable a multi-core cable with a reduced neutral.
Now, I talk about how to connect the cable to the panel or the load.
As I said earlier, the cable consists of a conductor, and the cable’s conductive material can be Aluminum or Copper. In most cases, we use copper conductors for their high conductivity, which can reduce the cable’s final size and diameter.
The conductor material can be solid, stranded, or flexible.
The conductor’s highest conductivity for the same cross-section area from high to low, flexible conductor then, stranded then, solid.
The reason for this high conductivity is the skin effect as current passes through the conductor.
So, to connect this conductor (which is copper, as this is the most common) to a copper bar or breaker, we shall use a method that provides direct contact and prevents any loss of connection, which can cause sparks, high currents, and later fires.
That’s why we shall use cable terminals; these cable terminals for small-cable cross-sections are usually pre-insulated, for example, for conductors 1.5mm2, 2mm2, 3mm2, 4mm2, and 6mm2.
But for larger cables, we will use cable lugs.
The purpose of these lugs is to insert the conductors and ensure tight, proper contact with the bar or breaker.
The cable lugs are conductive on both sides, the inner and the outer.
For the electrical installation, we need to cover the conductive materials with an insulating material, and that’s where heat shrink comes into play.
Heat shrink tubing is a tube made from materials that provide insulation for conductive materials.
This tube is shrinkable, shrinking around the object (bar, lug, etc.) when we apply heat.
In other words, the heat shrink tubing is a protective covering that protects the conductive parts from the surrounding environment.
We can also see that the heat shrink tubing is installed on the copper bars of the panels, as shown in this photo.
The heat shrunk parts have different colors, and we will choose their colors based on the phase or application color.
To choose the proper size of the heat shrink tubing, we need to identify two main factors: the first one is the diameter of the heat shrink before it shrinks, which we call the dimension (as supplied).
The other factor is its dimension after it shrinks; we call this dimension the (after-recovery) dimension.
To choose the correct heat shrink for its after-recovery & as-supplied dimensions, we shall first determine the outer diameter of the cable, conductor, or bars on which we will apply the heat shrink.
For example, if the conductor diameter is 18mm, we shall use a heat shrink whose dimension after recovery is less than 18mm, at the same time, it’s as supplied dimension to be bigger than 18mm, and we can control the diameter of the shrinking from the heat source that we apply to the heat shrink.
At the same time, we shall ensure that the As-supplied dimensions of the heat shrink are larger than the cable or conductor’s outer diameter.
The above table shows a conductor size, cable size, heat shrink size, and the correct part number for the heat shrink.
This is a list of the tools which will be required to complete the job, plus panel termination:
You can also read:
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If you like to learn the electrical practical installations on-site step by step in the help with practical photos and videos, please check the following link
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