Single Core Cables

1. Selection Of Number Of Cable Cores With Emphasis On Sizing
Parameters
The selection of number of cable cores basically depends on the type of
system where it is going to be installed.
Generally we have two types of systems:
A perfectly balanced system and
A system with some degree of unbalance (or Unbalanced System).
Generally cable sizing includes below parameters:
Cable installation conditions and the load it will carry
Continuous current rating of the cable
Voltage drop and short circuit considerations
Earth fault loop impedance
Lecture Notes by Dr.R.M.Larik 1

2. Why do we use copper tape on
underground cables? .
• Copper screen on the underground cables are for folowing reasons
• To relieve electrostatic stresses from the insulaton of the core.
• To earth the leakage fault currents or the capacitive currents
preventing damage to the insulation.
Lecture Notes by Dr.R.M.Larik 2

3. What is the difference between single core and multicore
cables?
• Cables are used literally everywhere, from Factories to parking lots, streets to malls for
transmitting electricity or telecommunication signals. All electrical gadgets, machines and
computers have one thing in common i.e. cables. Cable construction varies according to the
application and the condition it might be used in. All cables generally have a core or a conductor,
an insulation material, a jacket and armour.
• Single core cables and multi core cables have different construction and application area. Single
core cables as the name suggests have a single conductor usually made up of copper or
aluminium and insulation around it. Even though it has a single conductor its gauge and thickness
can differ. Larger the diameter of the cable lesser the flexibility achieved from it. Now, conductor
in these wires can be a solid or stranded in construction. Solid single core cables have a good level
of rigidity and toughness to it but are less flexible than stranded construction. Single core cables
can sometimes be chosen for particular applications due to it being less costly and are rugged in
construction. Single core cables can be chosen at times when duct size is small or where a longer
cable is required between joints.
Single Core Cable
Lecture Notes by Dr.R.M.Larik 3

4. Single Phase Power cables
• Two core and earth cable: This cable connects the consumer unit (fuse box) to the
power outlet sockets and carries the electricity to appliances which are plugged in to the circuit.
The cable has three cores, a live core, a neutral core and the earth core. The live and neutral cores
are insulated and carry the current to and from the outlet socket. The earth or earth continuity
conductor (ECC) is not insulated, except for the outer sheath, and provides a path for the current
to flow to ground should a fault develop.
•
Lecture Notes by Dr.R.M.Larik 4

5. USES OF SINGLE CORE CABLE
A single core wire is a cylindrical strand of metal. In single core wire
there is only a single core of metal is present, mostly copper or
aluminium
• Used for Domestic purpose
Single core wires or cables are widely used Domestic purpose. They are mainly used in electrical
appliances, these wires can take a good load that is why they are more preferred in domestic
uses.
• Can handle high temperature
Single core cables are very high ambient wires; these cables are a good conductor of electricity as
well as heat. These cannot melt or burn easily.
Lecture Notes by Dr.R.M.Larik 5

6. • Multi core cables on the other hand have more cores in it as compared to other wires of the same
type. Multi core cables have its cores grouped together in a single cable where these multiple
cores carry out its own defined purpose. Multi core cables can be used for power transmission or
data transmission. Due to multiple cores grouped in a single cable these multi core cables split at
the end of so as to be connected to their respective functions. Multi core cables can have a heavy
duty jackets to protect it against the environmental elements and other harmful factors but this
adds to the overall weight of the wire considerably.
• Multi core cables being versatile in nature find application in various fields like automobiles and
industrial facilities. These cables prove to be of tremendous help in places where space is limited.
Multi Core Cable
Lecture Notes by Dr.R.M.Larik 6

7. • Multi core cables
Multi core cables are cables, which contains more than one core in
the cable. These are flexible cables which are widely used for electric
purpose, these cables are professionally made with good quality.
• Used for industrial purpose
Multi wires or cables are widely used for industrial purpose. These
cables are the good conductor of electricity and can take loads and
benefits in industrial sectors. It can take heavy load and can support
heavy industrial machines.
• Use in Entertainment sector
Multi core cables are widely used in the entertainment sectors like
theaters, concert venues and many others. People use multi core
cable and combine their power, AV and data to avoid any tangled
cable.
Lecture Notes by Dr.R.M.Larik 7

8. 3-Core Cables
These cables are used generally for a perfect balanced 3-phase system. When the currents on the
3-live wires of a 3-phase system are equal and at an exact 120° phase angle, then the system is said
to be balanced. The 3-phase loads are identical in all respects with no need of a neutral conductor.
3.5-Core Cables
A 3-phase system may have a neutral wire. This wire allows the 3-phase system to be used at higher
voltages while it will still support lower voltage single phase loads.
It is not likely in such cases that the loads will be identical, so the neutral will carry the out-of-
balance current of the system. The greater the degree of imbalance, the larger the neutral current.
When there is some degree of unbalance and the amount of fault current is very small, then 3.5
core cables are used. In these types of cables, a neutral of reduced cross section as compared to the
3-main conductors is used, which is used to carry the small amount of unbalanced currents
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9. 3.5 Core Cable Construction
Lecture Notes by Dr.R.M.Larik 9

10. 4-Core Cables
• When there is severe out-of-balance conditions, the amount of fault current will raise to a very high
level. Generally in the case of linear loads, the neutral only carries the current due to imbalance
between the phases. The non-linear loads such as switch-mode power supplies, computers, office
equipment, lamp ballasts and transformers on low loads produce third order harmonic currents
(Definition of Harmonics and Their Origin) which are in the phase of all the supply phases.
• These currents do not cancel at the star point of a three-phase system as do normal frequency
currents, but add up, so that the neutral carries very heavy third harmonic currents.
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11. 5 and 6-Core Cables
Some conditions may arrive when the amount of fault (neutral) current becomes very large than
the phase currents. When the load concerned to this type of situation is fed through a multi-core
cable, it is necessary to use a 5-Core or 6-Core Cable. In this condition, two (or three) conductors
can be used in parallel formation to carry the high amount of generated unbalanced currents.
Lecture Notes by Dr.R.M.Larik 11