Frequently Asked Questions
Electricity is a versatile form of energy used to power anything from huge data centers and critical systems to many of our everyday electrical appliances. It can be generated and transferred very easily. Electricity, or electrical energy, can be created and converted from energy generated from other forms including thermal energy from burning fuels, wind energy harnessed by turbines, nuclear energy, and solar energy. This energy can either be used as it is generated or it can be stored in batteries or fuel cells.
Electricity is associated with electric charge which can be either a static charge or a dynamic charge. Although static charge electrical energy has its uses, it is the dynamic charge or flow of electric current which is most useful.
So what is electricity made of? At its simplest, all matter is made up of atoms, which are themselves made up of three particles: neutrons, protons and electrons. Neutrons have no charge; positively charged protons which are bound around the neutrons in the atomic nucleus; and negatively charged electrons which orbit the nucleus. The flow of electricity is associated with the loosely bound electrons flowing from one atom to the next. The more loosely bound the electrons in a material’s atomic structure are, the better the material is at conducting electricity. Metals are good electrical conductors whilst poor conductors or insulators such as plastics have tightly bound electrons in their atomic structure and don’t allow electric current to flow easily.
Electrical cables work by providing a low resistance path for the current to flow through. Electrical cables consist of a core of metal wire offering good conductivity such as copper or aluminium, along with other material layers including insulation, tapes, screens, armouring for mechanical protection, and sheathing. These additional layers are designed principally to allow the metal core to continue to conduct electrical current safely in the environment it is installed in.
A good conductor is made of a material whose atomic structure has loosely bound electrons in its outer shell which can move across the atomic matrix of the material (see our FAQ on ‘what is electricity’ for more information on atoms) This movement of electrons is known as the current flow. On the contrary, good insulators have tightly bound electrons which make it difficult for this current flow.
Electrical current flows from a point of positive charge to a point of negative charge whilst essentially the electrons flow in the opposite direction.
AC stands for an alternating current. Essentially the polarity of the supply is changing with time and as it does the current flows in one direction and then the other. Mains power generation is typically AC – most generators are based on an alternator which creates an alternating current as the wire stator turns within a magnetic field. AC power transmission is also preferred for high voltage mains transmission because it is relatively easy to step down the voltages for various applications with transformers. The frequency of this alternating direction for mains supply in the UK is 50Hz, or 50 cycles per second.
DC stands for direct current. Here the current flow is in the one direction only and does not alternate. This is typical of the sort of current produced by a battery. Power generated by photovoltaic panels is DC and would need to be converted with a power inverter to be used for standard mains applications. DC power, once generated, is very useful in speed control motors etc.
When the International Electrotechnical Commission (IEC) member countries and affiliate members are added together, the IEC family covers more than 97% of the world’s population. The members are the national committees of the respective country, responsible for setting national standards and guidelines.
The IEC controls the publication of 212 standards associated with electric cables which come under the remit of the Technical Committee 20 of IEC. Of course, these countries do not exclusively use only IEC cable standards and have their own National types; however they do recognize many of the IEC standards and work towards the ongoing harmonization of standards and test methods etc.
Full affiliate members of the IEC include:
Algeria, Argentina, Australia, Austria, Belarus, Belgium, Brazil, Bulgaria, Canada, Chile, China, Columbia, Croatia, Czech Republic, Denmark, Egypt, Finland, France, Germany, Greece, Hungary, India, Indonesia, Iran, Iraq, Ireland, Israel, Italy, Japan, Korea Republic of (South Korea), Libya, Luxembourg, Malaysia, Mexico, Netherlands, New Zealand, Norway, Oman, Pakistan, Philippines, Poland, Portugal, Qatar, Romania, Russian Federation, Saudi Arabia, Serbia, Singapore, Slovakia, Slovenia, South Africa, Spain, Sweden, Switzerland, Thailand, Turkey, Ukraine, United Arab Emirates, United Kingdom, United States of America.
There are an additional 22 associate members:
Albania, Bahrain, Bosnia & Herzegovina, Cuba, Cyprus, Democratic People’s Republic of Korea (North Korea), Estonia, Georgia, Iceland, Jordan, Kazakhstan, Kenya, Latvia, Lithuania, Malta, Moldova, Montenegro, Morocco, Nigeria, Sri Lanka, The Former Yugoslav Republic of Macedonia, Tunisia and Vietnam. Additionally, there are 83 affiliate members.
IEC standards cover the whole spectrum from low voltage, medium voltage and high voltage power cables and cable accessories in various material types and for a wide range of applications including but not limited to fiber optic cables, mineral insulated cables, heating cables, ground lighting cables for aeronautics, data cables, power control and instrumentation cables for shipboard and offshore applications.
The most widely recognized International standards bodies are the IEC, the ISO, and CENELEC.
IEC is the International Electrotechnical Commission
ISO is the International Organization for Standardization
CENELEC is the European Committee for Electrotechnical Standardization.
This is a term for the maximum current carrying capacity, in amps, of a particular device. The current carrying capacity is normally associated with electrical cable and is determined as the maximum amount of current a cable can withstand before it heats beyond the maximum operating temperature. The effect of resistance to current flow is heating and this is dependent upon the size of the conductor, the insulation material around the conductor, and the installation environment. The larger the conductor size the lower the resistance to current flow, meaning less heat associated with this resistance. Increasing the conductor size increases the current carrying capacity. Similarly, the higher the temperature resistance of the insulating material, the higher the ampacity or current carrying capacity. A 90°C rated insulation will have a higher current carrying capacity than a 70°C rated insulation.
The installation environment and the temperature of this environment affects the ability to dissipate heat away from the cable and so also affects the current carrying capacity. Cable used in air or ground at lower temperature will have a higher current carrying capacity than cable in air or soil at higher ambient temperatures.
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 with passive elements in the circuits including cables, contacts and connectors affecting the level of voltage drop. The longer the circuit or length of cables the greater the voltage loss. The impact of a voltage drop can cause problems such as motors running slowly, heaters not heating to full potential, lights being dimmed. To compensate for voltage drop larger cross-sectional sized cables may be used which offer less resistance / impedance to current flow.
Voltage drop can be calculated from the formula:
Vd =mV/A/m x I x Ib ÷ 1000
mV/A/m = the voltage drop per metre per amp
I = the length of the circuit conductor
Ib = the design current
The allowable voltage drop for low voltage installations supplied directly from a public low voltage distribution system is 3% for lighting and 5% for other uses.
An Ohm is the SI unit for electrical resistance and is symbolized by the Greek letter Ω.
The Ohm is related to the current and voltage in a system: a current of 1 amp through 1 ohm of electrical resistance produces a voltage of 1 volt across it.
The formula for this is I=V/R where:
I = the current through the conductor
V = the voltage measured across the conductor
R = the resistance of the conductor
Materials with a low resistance make good conductors – examples include copper and aluminium – whereas materials with very high resistance which make good insulators, such as Polyvinyl Chloride (PVC) and Polyethylene (PE).
Conductors are typically measured in Ohms (Ω) whereas insulators are measured typically measured in Mega Ohms MΩ.
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.
Conductor resistance is the inherent resistance to current flow in a conductor.
The more electrically conductive a material is, the less resistance it offers to current flow. The more resistant the conductor is to current flow, the less conductive it is.
Due to its excellent electrical properties as well as ready availability, copper is the metal most frequently used for electrical conductors. In 1913 the International Electrotechnical Commission (IEC) established a standard for copper conductivity, the International Annealed Copper Standard (IACS), based on the resistivity of annealed copper being equal to 100 percent conductivity.
Although the unit of conductivity is the Mho, its reciprocal, the Ohm is more usually used to express both resistance and thus a measure of conductivity – the lower the resistance in Ohms, the more conductive the material.
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.
Current is the measure of the amount of electrical charge moving through a specified point in a unit of time. An ampere of current is flowing when a charge of 1 coulomb passes a point in a second.
The symbol for an ampere is A.
We manufacture the following types of cables:
- LT Cables of voltage grades; 250/440, 300/500, 450/750, 600/1000
- Volts and up to 1900/3300 volts
- Flexible and special cables both in Shielded and Unshielded form
- Aluminum Overhead Conductor (AAC)
- Aluminum Conductor Steel
- Reinforced Aluminum Conductor Steel (ACSR)
- Overhead Bare Copper Conductor (OHBCC)
- Tinned Copper Conductor
- All our cables are manufactured with PVC, PE, LSZH (low smoke zero halogen) and XLPE (cross link polythene)
General wiring cables and 2 Core, 3 Core, 3.5 Core and 4 Core, Copper Conductor/PVC insulation/PVC sheathed 600/1000V are available in ready stock.
Typically it takes one to two weeks (depending upon the type of cable, stock position and quantity required).
Fast Cables has an edge over others due to several factors. Fast Cables offers the following:
- Products manufactured under ISO 9001 Quality Management Systems and Procedures
- 100% conductivity and insulation according to BSS and IEC Standards
- Trouble free operation during electrical operations
- National and International Certifications
- Direct supply and services to customers
- Focus on quality and reliability
- Customer Orientation
All our products are under warranty in accordance with the 17th Edition of IEEE Wiring Regulation for any manufacturing fault. Manufacturing of our product is in accordance with BSS and IEC Standards and Quality Management System. Product life may be more than 15 years.
We sit amongst the top few leading companies in the cable industry of Pakistan, with a reasonable share in export market as well.
We require 100% payment before delivery is made following inspection and testing at Fast Cables’ premises.
All our cables are Fire Retardant. The PVC used for installation and sheath has self-extinguishing properties. This helps in stopping the propagation of fire.
However, we can manufacture 100% Fire Resistant (FR) cables, meant for highly specific areas, on customer demand as per the recognized international standards.
There is no connection between the purity and the hardness/softness of the copper. Copper having 100% conductivity might be hard due to wire drawing while passing through different dyes, whereas the same copper might go soft while passing through annealing process.
After a type test is successfully performed on a certain cable with a specific conductor cross sectional area and rated voltage, that type approval is valid for same cable type with other conductor cross sectional areas and/or rated voltages satisfying the conditions as per the IEC specifications.
Discharges in a cable are caused by the breakdown of gas contained within the voids in the insulation. These tiny discharges release the electrical charge which can be detected using highly sensitive equipment. The voltage at which the breakdown first occurs is known as the discharge inception voltage and the charge is measured in Pico Coulombs (pC). These discharges can cause cable failure in service, therefore it is essential to detect these during routine tests of each cable.
Specifications for MV polymeric cable require measuring any partial discharge and defining the maximum level of acceptable discharge at particular test voltages. However, any discharge detected should be identified and eliminated even if it is below specification limit.
This is the method used in Australia, UK, Asia and Europe to indicate the voltage rating of a cable. The first number indicates the voltage rating of the insulation to ground and the second number indicates the voltage rating from one insulated conductor to another insulated conductor. Generally the second number is used if a cable is referred to by one voltage.
For example, a 19/33kV cable is often referred as a 33kV cable.
This is the minimum thickness of insulation required on the cables to offer a practical level of resistance to mechanical damage. If such thickness is not used to insulate 240 volts, the covering will be easily damaged.