10 November 2020

How do you differentiate between one cable and another?

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.

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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).

How to identify electrical cables by colour

In Spain and most European countries, regulations establish a colour code to facilitate the identification of electrical cables. This system allows for the quick identification of the function of each conductor and reduces the risk of errors during installation or repair.

¿What is each cable for?

You can tell the fuction of each one by its colour:

Green and yellow: earthing.
Blue: neutral.
Brown, grey, black o white: phase.
Striped colours: neutrals.
Coloured: current or charge.

Green and yellow cable (earth): this is the safety wire. Its function is to divert the current to earth in the event of a leak or electrical fault, preventing electric shocks to people and damage to appliances. It must always be present in modern installations.
Blue cable (neutral): closes the electrical circuit by returning the current to the mains. Blue has been used to identify it since 1970, although in older installations it was common to find it in red.
Brown cable (phase): carries the current from the mains to the devices. Although the most common colour is brown, it can also appear in black or grey, depending on the appliance or the installation.
Black cable (phase): like the brown one, this is a phase conductor. In some installations, it may be replaced by a white cable. It is one of the most visible cables in homes and commercial premises.
White cable (neutral in certain installations): it is used as a neutral wire in some systems. On occasion, it is also connected to the transformer to return energy, fulfilling a function similar to that of the blue cable.
Striped cables: these are used to identify different neutral conductors within the same installation. The stripes make it possible to distinguish which neutral cable corresponds to each colour circuit.
Solid colour cables (without stripes): generally, these are phase or load cables. The most frequent is red, used to carry current to devices.

The function of each cable

In summary, cables are distinguished into three important groups, which are:

Phase: supplies the energy necessary for appliances to work.
Neutral: returns the current to the mains, closing the circuit.
Earth: protects people and equipment against possible electrical faults.

Together, these three cables guarantee that electricity circulates in a controlled and safe manner. Without them, the risk of short circuits, fires or electric shocks would be much higher.

“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.

Signs that cables may be incorrectly identified

Although regulations establish standard colours, errors may exist in older installations or those that have been manipulated incorrectly. Some warning signs are:

Colours that do not correspond: for example, a red cable used as a neutral.
Absence of an earth cable: very common in older properties.
Improvised splices: cables joined with insulating tape without respecting colours or functions.
Frequent tripping of the RCD (trip switch): this may indicate that the cables are incorrectly connected.
Burning smell or overheating: a symptom that the installation is not functioning correctly.

If you detect any of these situations, it is highly recommended that you contact an authorised electrician to check the installation.

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:

Repairs in your installation: If there is an emergency, the technician will be at your home within 3 hours of your call.
Travel and the first 3 hours of labour are free of charge.
Repairs to your domestic appliances (washing machines, dryers, refrigerators, freezers, cooker hoods, dishwashers, ceramic hobs, electric cookers and electric ovens), locksmith service, plumbing and window repairs.
Electricity bill payment protection insurance.

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