Understanding Electrical Wire and Cable sizes and uses in Nigeria

Electric Wires and Cables

When you have a building project in Nigeria, electricians and contractors quote for and tell you a lot of jargon u must understand, hence understanding Electrical Wire and Cable sizes and uses in Nigeria is essential so that you can make the right decisions and not be in total darkness for want of information and education. This article tells a lot about the types of electrical wire and cable always used in Nigeria.

Electrical Wire and cable and their uses by voltage source

An electric cable is measured in volts and, depending on these, they are categorized into one group or another:

  • Low voltage cables (up to 750 V): in a variety of applications, and with thermoplastic and thermoset coatings. They are designed and built according to harmonized standards.
  • Low Voltage cables (up to 1,000 V): (also called (0,6/1 kV) The cables in this section are used for industrial power installations in various fields (general industry, public installations, infrastructures, etc.). They are designed according to international standards (UNE, IEC, BS, UL).
  • Medium Voltage cables: from 1 kV to 36 kV. They are used to distribute electricity from electrical substations to transformer stations.
  • High Voltage cables: from 36 kV. They are used to transport electricity from the generating plants to the electrical substations.

For the purpose of this article, we will stick with the low voltage cables of up to 750V.

Types of electric cables and where they are used 

Low voltage cables

Cables for electric panels

These are flexible cables that are used for wiring electric cabinets. These electric cables are especially suitable for domestic use, for installation in public places, and for internal wiring of electrical cabinets, switch boxes, and small electrical appliances.

Power cables

Power cables or Energy cables are for industrial facilities and public places. It is common to find power cables in applications for power transmission in all types of low voltage connections, for industrial use, and for variable frequency drive (VFD).

Armored cables

Cables with aluminum or steel reinforcement for installations with risk of mechanical aggression. It is also common to find armored cables in places where rodents are present, as well as in installations on premises with a risk of fire and explosion (ATEX). The Atex cables are used only in places that are prone to explosive gases like mines, oilfields, and refineries where flammable gas may exist

Rubber cables

The use of extra flexible rubber cables is very varied. We can find rubber cables in fixed industrial installations as well as in mobile services. Welding cables should have a rubber sheath, which allows high currents to be transmitted between the welding generator and the electrode.

Halogen-free cables

High-Security Halogen Free (LSZH) Cables with low smoke and corrosive gas emission in case of fire are suitable for use in wiring of electrical panels and public places, installations of all kinds in public places, individual derivations, emergency circuits, public distribution networks, and also for mobile service.

Fire resistant cables

These cables are specially designed to transmit electrical energy in the extreme conditions that occur during a prolonged fire, guaranteeing supply to emergency equipment such as signaling, smoke extractors, acoustic alarms, water pumps, etc. Their use is recommended in emergency circuits in places with public concurrence.

Control cables

Control cables for fixed or mobile installations should be extremely flexible, as they are mainly designed for small household appliances, for the interconnection of machine parts used for manufacturing, for signaling and control systems, for the connection of motors or frequency converters, for signal transmission where the voltage induced by an external electromagnetic field may affect the transmitted signal or for power supply connections to avoid generating electromagnetic fields.

Instrumentation cables

These are flexible and shielded cables for the transmission of signals between equipment in industrial installations. Especially suitable for optimum data transmission in environments with a high level of electromagnetic interference.

Solar cables

These cables are particularly suitable for connecting photovoltaic panels, and from the panels to the DC to AC inverter. Thanks to the design of their materials and their cover, which is especially resistant to solar radiation and extreme temperatures, they can be installed outdoors with full guarantees.

Special cables

There is a wide variety of electric cables for special installations such as: temporary light garland installations at trade fairs; connections for overhead cranes, hoists, and lifts; applications in submerged pumps and drinking water areas such as aquariums, purification systems, drinking water fountains or in swimming pools for lighting, purification and cleaning systems.

Aluminum cables

Aluminum cables for power transmission are suitable for fixed installation indoors, outdoors, and/or underground.

Types of electric conductors

ELectric wire cables also known as conductors have different types and each type is appropriate for its application.

  • Bare wire conductor: single wire in a solid state, not flexible, and without coating.
  • Aluminum electrical conductors: in some cases, aluminum conductors are also used, despite the fact that this metal is 60% worse conductor than copper.
  • Copper electrical conductors: the most commonly used material.
  • Flexible copper wire conductor: it is a set of fine wires covered by an insulating material. They are flexible and malleable.
  • Single-core cable: a cable with a single conductor.
  • Multi-core cable: a cable that has several conductors.

Measurement criteria of electrical wire and cables

There are two sizing criteria for copper conductors:

  • In the AWG-American Wire Gauge, conductors are defined by specifying the number of wires and the diameter of each wire.
  • In European sizing (mm2), the conductors are defined by specifying the maximum resistance of the conductor (Ω/km). Solid or flexible conductors are defined by specifying the minimum number of wires or the maximum diameter of the wires that form it. In addition, the actual geometrical sections are somewhat smaller than those indicated as nominal.

Nigeria uses the European sizing in mm, so when you hear the electrician say 3mm or 10mm just know they are referring to the thickness of the wires. also as you read further you will understand that the thicker the wire the more current it consumes, a 25mm2 cross-sectional area wire must consume more current than the 16 mm2 wire. Remember that your electrical billings take account of the amount of current consumed in your facility

Electric cable measurements

CROSS-SECTION in mm2(AWG)CURRENT CONSUMPTIONUSED
25 mm24Very highCentral air conditioning and industrial equipment..
16 mm26High airConditioners, electric stoves and electric power connections.
10 mm28Medium highRefrigerators and dryers.
6 mm210MediumMicrowave and blenders
4 mm212MediumLighting
2.5 mm214UnderLamps
1.5 mm216Very lowThermostats, bells or security systems.

Types of colors in electrical cables and their meaning

The colors of the electrical cables are governed by the International Electrical Commission Standard IEC 60446. For the identification of the conductors, the following colors are allowed: black, brown, red, orange, yellow, green, blue, violet, gray, white, pink, and turquoise.

  • Neutral conductor: blue. It is recommended not to use more blue conductors to avoid confusion.
  • Phase conductor: black, grey, or brown.
  • Protective or earthing conductor: two colors, yellow and green. The use of yellow or green single-colored cables is only permitted in places where, for safety reasons, there is no possibility of confusion with the earthing system.

Nomenclature of electrical cables according to standards

Finally, we will go through some of the nomenclatures of electrical cables according to their standards, each cable has a standard designation. This designation is composed of a set of letters and numbers, each with a specific meaning. This designation refers to a series of product characteristics (materials, nominal tensions, etc.) that facilitate the selection of the most suitable cable for your needs, avoiding possible errors in the supply of one cable by another.

When a cable does not clearly indicate these data, it may be a defective cable, which does not comply with safety regulations or guarantee the cable’s life and proper operation.

Designation according to the type of insulation

nomenclatureCable type
RCrosslinked polyethylene (XLPE)
XCross-linked polyethylene (XLPE)
Z1Halogen-free thermoplastic polyolefin
ZHalogen-free thermosetting elastomer
VPolyvinyl chloride (PVC)
SThe halogen-free thermosetting silicone compound
DEthylene-propylene elastomer (EPR)

There is a lot of information on electrical wire and cables that you must learn about, however, this article will not go deep into all that is necessary to know about cables hence we have restricted it to the only cable used within facilities that require only low voltage.

Contact us to buy from our partner online store if you have a need for electrical cable and wire or electrical material and accessories supplies in Nigeria.

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