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Frequently Asked Questions

 

As cable experts we get asked questions covering everything from general electrical information to more specific queries about cable construction, specific electrical wires for applications, and the cable industry as a whole. As part of the technical support services we offer our customers we're always pleased to help and some of the more frequently asked questions, as well as some general technical information is explained below.

 

Cable knowledge from the cable experts

A sound technical understanding of cables and their applications is important for a number of roles and responsibilities across the industries. Just as we make sure our staff benefit from cable training from our experts, we believe that our customers should have access to this insight too. We offer a range of CPD-certified cable training courses delivered by our cable experts, including introductions to cable manufacturing, cable testing and standards, medium voltage cables, fire performance cables and their standards, and Network Rail approved cables. Tailored cable training programmes are also available to meet specific applications and cable ranges. 

If you would like to know more, then contact us and learn about cables from the experts. 

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General Electrical Questions

Q

What is electricity?

A

Electricity is a form of energy associated with electric charge. This charge can be either a static charge or a dynamic charge...

Q

How do electrical cables work?

A

Electric cables work by providing a low resistance path for the current to flow through. Electric cables consist of a metal wire or core offering good conductivity such as copper or aluminium...

Q

What is the difference between AC and DC?

A

Electrical current flows from a point of positive charge to a point of negative charge whilst essentially the electrons flow in the opposite direction...

Q

Which countries routinely use IEC cables?

A

When the International Electrotechnical Commission (IEC) member countries and affiliate members are added together...

Q

Who are the leading international standard setting bodies for electrical cables?

A

The most widely recognised International standards bodies are the IEC, the ISO, and CENELEC. IEC is the International Electrotechnical Commission, ISO International Organisation for Standardisation...

Q

What is ampacity?

A

This is a term for the maximum current carrying capacity, in amps, of a particular device. The current carrying capacity is normally associated with electric cable...

Q

What is voltage drop?

A

A voltage drop in an electrical circuit normally occurs when a current passes through the cable. It is related to the resistance or impedance to current flow...

Q

What is an ohm?

A

An Ohm is the SI unit for electrical resistance and is symbolised by the Greek letter Ω. The Ohm is related to the current and voltage...

Q

What is electrical conductivity and conductor resistance?

A

Electrical conductivity and conductor resistivity are essentially the opposite of each other: Electrical conductivity is the ability of a material to conduct an electrical current...

Q

What is an ampere?

A

An ampere, or amp as it is more commonly referred to as, is the standard unit of current. It is determined as the amount of current which flows when a potential difference of one volt is applied across a resistance of 1 ohm...

Q

What is voltage rating?

A

The voltage rating of a cable is the highest voltage that may be continuously applied to a cable construction in compliance with the relevant cable standard or specification...

Q

What is a volt?

A

The volt (symbolized V) is the Standard International (SI) unit of electromotive force or the potential difference required to carry 1 ampere of current through a resistance of 1 Ohm...

Q

What is capacitance?

A

Two conductors which are separated by a distance can store an electric charge between them. A cable or harness with two or more wires can also store a charge and this can affect the way the cable performs...

Q

What is fault current?

A

The fault current is the electrical current which flows through a circuit during an electrical fault condition. A fault condition occurs when one or more electrical conductors short to each other or to ground...

Q

What is dielectric strength?

A

The Dielectric strength of a material is a measure of the electrical strength of an insulator. It is defined as the maximum voltage required to produce a dielectric breakdown...

Q

What is inductance?

A

When a current flows through a conductor it produces a magnetic field around the conductor. If this induced magnetic field changes with a changing current it produces an electromotive force...

Q

What is impedance?

A

Impedance is measured in Ohms and represents the total resistance that the cable presents to the electrical current passing through it. Impedance is associated with AC circuits...

Q

What is attenuation in cables?

A

Attenuation is generally associated with data cables and refers to any reduction in signal loss, calculated as a ratio of the power input signal to output signal...

Q

What are electrical phases?

A

The mains supply to most homes is a single phase alternating current (AC) supply. Unlike the current supply from a battery which is a direct current (DC) supply...

Q

What is electromagnetic interference?

A

Electromagnetic interference is abbreviated as EMI. EMI is the disturbance which is unintentionally generated by an external source that effects the electrical circuit by electromagnetic induction...

Q

How is electrical energy generated from solar power?

A

Sunlight is converted into electrical energy by photovoltaic (PV) cells. The PV cells consist of layers of semi conductive material designed to be either n type (negative) or p type (positive)...

Q

How is electrical energy generated from wind power?

A

Electrical energy is generated from wind in the way most electrical energy is generated, via an electrical generator which converts mechanical energy into electrical energy...

Q

How is electricity carried over long distance and what is the electricity loss?

A

As current passes through a wire it encounters resistance to the current flow, this causes some of the electrical energy to be converted into heat energy which is dissipated to the surrounding area. Read more about the effect of this, AC power and High Voltage DC...

Q

What is the definition of low voltage, medium voltage, high voltage and extra high voltage?

A

Definitions vary somewhat but a general guide to the voltage categories are as follows...

Q

What is the history of electrical cables?

A

The earliest use of recognisable electric cable was probably the early commercialised Telegraph lines such as that strung between Washington, D.C, to Baltimore, Maryland in 1844...

Q

What are cable ratings?

A

Cable ratings determine the parameters within which the cable can be safety used. The most typical cable ratings are Temperature, Voltage and Current...

Q

What are the Ethernet Standards?

A

Ethernet LAN technology defines the number of conductors that are required for a connection, the performance thresholds that can be expected, and provides the framework for data transmission...

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Cable Construction Questions

Q

What are the various electrical cable types and what dictates their construction?

A

There are a multitude of different types of electrical cable used for the power distribution, supply, control, signal, or data transmission across various industrial...

Q

What are the respective benefits of using copper vs aluminium conductors?

A

Copper and aluminium are used as the electrical conductors in electric cables due to their low resistance and excellent conductivity. These metals are both ductile and ...

Q

What are the benefits of PVC insulated cables?

A

PVC (Polyvinyl chloride) is widely used in electrical cable construction for insulation, bedding and sheathing. It was the 1950s when PVC...

Q

What are the benefits of XLPE insulated cables?

A

XLPE or Cross-linked polyethylene is a thermoset insulation material. Crosslinking polymers is a process which changes the molecular structure ...

Q

What are the benefits of Rubber insulated cables?

A

Rubber has been used as cable insulation and sheathing material long before other insulation such as PVC and PE can to be commonly applied...

Q

What are the benefits of MDPE insulated cables?

A

MDPE stands for medium density polyethylene. This material is used principally as a sheathing material on larger size cables...

Q

What are the benefits of Silicone insulated cables?

A

Silicone rubber insulated cables have outstanding thermal range with some suitable for temperatures as low as -90°C and as high as 200 °C...

Q

What are the benefits of PUR cables?

A

PUR or Polyurethane has been used for cable sheathing since the 1960’s and is a thermoplastic material with superior physical properties...

Q

What are the benefits of EPR insulated cables?

A

Ethylene Propylene Rubber is a generic term for a wide range of polymers based on copolymers of ethylene and propylene...

Q

What are the benefits of PE insulated cables?

A

Polyethylene is a semi-crystalline polymer available in a wide variety of versions with differing chemical structures, molecular weights and densities

Q

What are the benefits of PCP insulated cables?

A

PCP or Polychloroprene and was one of the first commercially available synthetic rubbers and is an exceptionally tough and flexible sheathing material with resistance to tears, abrasions...

Q

What are the benefits of CSPE sheathed cables?

A

CSPE stands for Chlorosulfonated polyethylene – it is a thermoset, cross-linked insulation and sheathing....

Q

What are annealed conductors?

A

When metal is cold worked or formed it becomes work hardened or strain hardened. Copper conductors go through a considerable amount of work...

Q

What is the difference between thermoplastic and thermoset insulation in electrical cables?

A

The plastic / polymers used in cable insulations are either thermoplastic or thermoset. Thermoplastic material is softened by heating and can be shaped...

Q

What is the operating temperature for electrical cable?

A

The operating temperature of an electrical cable normally refers to the minimum and maximum temperature that the cable can safely operate at for a sustained period of time...

Q

Why do certain cables have braiding?

A

Cables are braided for one of two reasons, either to electrostatically screen the cable or to provide mechanical strength to the cable. Applying a braid of metallic wires in the cable’s construction to achieve electrostatic screening...

Q

What are FTP (foiled twisted pairs) cables?

A

The term FTP stands for foil twisted pairs. FTP networking cables often support Ethernet LAN. The cables are designed and constructed with a twisted pair or multiple twisted pairs of cores...

Q

What are drain wires in electrical cables?

A

Drain wires are used in cables in conjunction with a metallic shield to ensure effective grounding. The drain wire serves to complete an electrical circuit from the shield...

Q

What makes electrical cables suitable for outdoor use?

A

A wide range of cables are suitable for outdoor use if they are protected from direct sunlight or other external influences. Read more about the methods and material types used for outdoor cables...

Q

How are cables jointed?

A

The conductors may be joined by either welding, crimping, soldering or mechanical connectors. The jointing insulation and shroud applied must be compatible with the cable materials....

Q

How are cables terminated?

A

Using the proper termination method is essential for maintaining the electrical and mechanical integrity of the cable. Read more about the solder, crimps, pins, and many more...

Q

What are longitudinally and laterally water resistant cables?

A

Laterally water tight ensures that water can’t penetrate into the cores of the cable, whereas the longitudinally one is designed with a barrier to longitudinal spread of moisture along the cable length...

Q

What are hydrocarbon resistant cables?

A

Hydrocarbons are organic compounds that are made of hydrogen and carbon atoms. They are found particularly in crude oil and natural gas...

Q

What are intrinsically safe cables?

A

Intrinsic safety is a protection technique for the safe operation of electrical/electronic equipment in hazardous areas where any ignition source needs to be eliminated...

Q

What are the BS5308 Pair Colour Codes?

A

Multicore pairs in cables manufactured BS5308 Part 1 cables or PAS5308 Part 1 are unscreened and identified by insulation colour in the following sequence...

Q

What is the DIN 47100 Core Colour Chart?

A

DIN47100 is a German DIN standard for the identification of individual cores by colour-coding for telecommunications cables...

Q

What are Earth Bonding Cable Size Selections?

A

The Earthing conductor and main protective bonding conductor sizes (copper equivalent) for TN-S and TN-C-S supplies are determined as follows...

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Cable Industry Questions

Q

How is the minimum bending radius determined for cables?

A

The minimum bending radius is a measure of the smallest radius a cable can be bent around without damaging the cable...

Q

What is the conversion between AWG and the metric system?

A

AWG or American Wire Gauge is a US standard measure for the diameter of electrical conductors. It is based on the number of dies originally required to draw the copper down to the required dimension...

Q

What are cable assemblies?

A

Cable assemblies are groups of cables which are arranged into a single unit for a particular purpose. Cable assemblies are also referred to as cable harnesses or wiring looms...

Q

What are backbone cables?

A

As the term suggests with its anatomical name, the backbone forms the major core of network from which other elements can then branch off from...

Q

What is bandwidth in cables?

A

Bandwidth for cables refers to the range of frequencies used for the transfer of information through data cables. The broader the bandwidth the more data that can be carried...

Q

What is cable lay?

A

Cable Lay refers to the lay length or length of twist or to the method and type of lay of electric cores or cables, sometimes known as cabling...

Q

What are earthing or bonding arrangements?

A

Earthing is a safety measure to prevent electric shock, whereas bonding is a term used for connecting together all the metallic parts that are not supposed to be carrying electric current ...

Q

What is the life expectancy of electrical cables?

A

There are many different environmental and operational conditions which are likely to influence the longevity of electrical cables in service. Read more about these factors and the experts' estimation on cables' life expectancy...

Q

How are cable sizes selected?

A

Cable size selection is based on 3 main factors: Current carrying capacity, Voltage regulation, Short circuit rating. Read more about the cable sizes and what determinate them...

Q

What are standard cable drums weights and dimensions?

A

Cable drums come in many different sizes and weights depending somewhat on the materials they are made of. Read more about drum sizes, materials and weights...

Q

How should electrical cable drums be handled / shipped?

A

Electric cable drums can be heavy and difficult to handle manually. A proper risk assessment should be done before handling drums. Discover the correct methods for handling, lifting and shipping cable drums...

Q

How are electrical cables tested for compliance?

A

Electric cables are tested for compliance against parameters which have been designed to determine their particular suitability. Read more about these tests and what they require...

Q

What are electrical cable routine tests?

A

Routine tests are tests which are conducted on each batch of cable and required to confirm ongoing conformity. Routine tests may differ from one cable type to the next...

Q

What are electrical cable type tests?

A

Type tests are predominately destructive tests, conducted to determine if the cable construction and materials are compliant with standard specifications. Type tests are only required to be done once and are generally not repeated...

Q

What is a spark test ?

A

A spark test is an inline voltage test used either during cable manufacturing or during a rewinding processes...

Q

What are the main causes of electrical cable failure?

A

There are many reasons why a cable may fail in service. Often this cable fault can have serious consequences for example causing a fire...

Q

How to protect electrical cables against mechanical and environmental damage?

A

Electric cables are installed in various environments and it is often necessary to provide protection to the cables to prevent mechanical and environmental damage...

Q

How should I select cable glands?

A

There are several different types of cable gland and choosing the right one for the application is very important. In choosing the right gland consideration needs to be given to the following...

Q

What are fire performance tests?

A

Fire performance tests for cables verify that the cable will continue to maintain electrical continuity or functionality for a defined period of time in a simulated fire condition...

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About Eland Cables

About Eland Cables

Established in 1975, Eland Cables is a supplier of power, data, instrumentation and control cables and cable accessories to the world's most demanding industries and to some of its most prestigious projects. Our reputation is built on an unswerving focus on quality, technical expertise and customer service.

Quality

Our focus on quality has resulted in our in-house specialist cable testing facility securing the ISO 17025 accreditation. This certifies the competence, impartiality and performance capability of our laboratory and its evaluations. In turn, it means peace of mind for our customers with regard to the quality of the cables they source from us.

Expert tecHnical support

Our highly-qualified technical team is on hand to provide technical support with all aspects of cable selection, technical specification, regulatory requirements, and bespoke cable design and manufacture.

Complete Cable Solutions

We are a key contributor to projects in over 100 countries every year, adding value through comprehensive technical support, reliable logistics, innovative solutions, and a customer-centric approach.

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