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Endesa - Electricity, Gas, People

How do you differentiate between one cable and another?

Published on February 22, 2019

They are everywhere, but we only pay attention to them when one of them needs to be replaced. Are all cables the same? How can you tell one from another? What is each one used for? We’ll clarify all your questions.

A cable is an element designed and manufactured to conduct electricity. They tend to be made of copper, though they can also be made of aluminium. Whether or not you see them, they form part of your life, because you depend on them to turn on a light bulb.

The composition of a cable is very simple: a conductor, the insulation, the filler layer and a cover.

Each element fulfils a mission:

  • Electric conductor: one or more copper / aluminium wires. It is the part of the cable that transports the electricity.
  • Insulation: covers the conductor and is responsible for the current not escaping from the cable.
  • Filler layer: it is inside the insulation and conductor. It is used to obtain a circular and homogeneous aspect.
  • Cover: protects the cable from the outdoors and external elements.

How many types of cable are there?

The universe of cables is incredibly complex and explaining them all in this post is unthinkable. We are going to focus on those that you’ll come across in your daily life. They may differ from each other based on several criteria:

  • Number of conductor wires: unipolar (only one conductor wire), multipolar (more than one conductor wire) or tubes (two or three conductor wires surrounded by protection).
  • Structure: they can be rigid or flexible, flat or round, coaxial (with a nucleus plated in copper), braided (formed by pairs of intertwined wires), with insulation or without insulation, with or without shielding, etc.
  • Type of conductor: bare wire (rigid and has no covering); insulated wire (like the previous one, but has an insulator that covers it); flexible cable conductor (the most common one); and cables.
  • Properties of the covering: a nomenclature is used to differentiate them: 1- T (Thermoplastic, is the most common), 2- H (Heat resistant, resistant to temperatures up to 75ºC), 3 – HH (Heat Resistant, resistant to temperatures up to 90ºC), 4 – W (Water resistant, resistant to water and moisture), 5 – LS (Low Smoke, low emission of smoke and other contaminants), 6 – SPT (Service parallel thermoplastic, two flexible and parallel plastic cables connected to each other, also called a duplex cable).
  • Type of insulation: thermoplastic or thermostable. Thermoplastics are polyvinyl chloride (PVC), polyethylene (PE) and polychloroprene, neoprene or plastic (PCP). For their part, thermostable insulation are cross-linked polyethylene (XLPE), ethylene-propylene (EPR), of copper plated or mineral insulated (MICC).

What does a cable’s colour mean?

Normally, the cable’s insulation is manufactured in one colour or another so that we can easily distinguish its function:

  • Green and yellow cable: earthing.
  • Blue cable: neutral cable. Until 1970, one with a red colour was used.
  • Brown cable: phase cable, though it also may be black or grey, depending on the colour of the apparatus that it is incorporated into.
  • Black cable: phase cable that can also be white. Seen in most installations.
  • White cable: neutral cable. These are also used for earthing, but they are only connected to the transformer to return the energy.
  • Cables with striped colours: neutral, like the previous ones. They are used to identify which neutral cable corresponds to each coloured cable.
  • Coloured cables: except for those that have stripes, they cables with a current or charge. The most common is the red one.

The earthing cable tends to be green and yellow. The brown and black ones are phase cables.

What is the purpose of the earthing, phase and neutral cables?

In your home’s plugs, you’ll see three cables: phase, neutral and earthing, each one with the aforementioned colours.

In normal conditions, the earthing does not have any electrical current and is only there to protect you. They are cables that go to your home’s electrical panel, and from there to the building’s earthing (an earth pin that, if necessary, carries the current underground). In the event of poor contact or a short circuit while you're handling an electrical apparatus, the earthing cable “traps” and expels from your house that electrical current, which otherwise would enter your body.

The phase cable is where the electrical current enters, and is the one you must be careful with, given that we are talking about a voltage of 220 or 230 volts. Only authorised professionals should handle them, and only after cutting the current.

Regarding the neutral cable, their function is to allow the current to “return”. In order to be transmitted, electricity needs two conductors, given that the current is only generated when the electrons move from one point to another. The voltage of your electrical installation is the difference of electric potential between the phase cable and neutral cable.

There is a way for all that we have said to be much simpler. It’s called not worrying at all and trusting the maintenance service that is in charge of your electrical installation:

  • Unlimited repairs in your installation: in case of an urgent matter, the technician will be at your home within 3 hours of your call.
  • The travel time and the first 3 hours of labour are free.
  • Includes one repair of a white-range home appliance and two handyman services per year (changing plugs, installing lights, etc.).