CABLE

CABLE

Electrical Cables

What is electrical cable?

• Electrical cable is a wire that is made up of 2 or more wires running side by side and bonded, twisted or braided together to form a single assembly.

• The end of wire cable is connected to 2 devices.

Example of bonded wire cable

Example of twisted wire cable

Example of braided wire cable

Purposes of wire cable

• To transfer electrical signals from one device to the other.

• It is used extensively in electronic devices for power and signal circuits.

Examples : Undersea cables is used for long distance communication

Example : Power cable to transmit bulk of electrical power whether in AC or DC

Example : Electrical cables that is used in building wiring for lighting, power system and control circuits

Multiple Select

Which is TRUE about the purpose of electrical wire cable?

• To transmit electrical energy from one end to the other.

• To propagate the electrical signal from the emitter to the receiver.

• As a pathway to transfer electrical energy

• As a medium for electrical distribution system.

Multiple Select

Is the electrical distribution and electrical transmission system are the same?

• Yes

• No

Parts of wire cable

• Wire cable can be categorized in of 3 different parts which are Conductor, Insulator and Sheathing (Inner and Outer).

• This 3 parts played different roles and important for the safety usage of the wire cable itself.

Multiple Choice

Which item is not the main parts of a wire cable?

• Insulator

• Sheathing

• Conductor

• Resistor

Figure 1 : Parts of wire cable

Multiple Choice

From Figure 1: Name part C

• Insulation

• Conductor

• Sheathing

• Inner sheath

Multiple Choice

From Figure 1: Name part D

• Insulator

• Inner Sheath

• Outer sheath

• Armoring

Cable Conductor

• It mainly used to carry electrical power from one device to the other.

• Is made up of highly conductive material such as copper.

• It can be categorized into classes based on the number of strands in it.

• Higher the class, more number of strands in conductor involved

• Class 1: Solid , Class 2: Stranded (7 or 19 strands), Class 5: Flexible (Due to multi-stranded) and Class 6 : Extra flexible (For dynamic used such as cords or welding)

Multiple Choice

Is Class 1 type of conductor is more fragile than Class 5 type?

• Yes

• No

Multiple Select

Beside Copper, choose the material can be used as a conductor

• Rubber

• Silver

• Aluminium

• Glass

Cable insulation

• To prevent the electrical current from leaking out of the cable.

• Mainly made up of high insulation material such as Poly Vinyl Chloride (PVC), Cross Linked Poly Ethylene (XLPE) or Rubber (Various type of rubber)

• Material used mostly based on its ambient operating temperature to enable in resisting high temperature.

Cable sheath

• To bundle the conductors together if there are multiple wires inside a cable.

• The cavity inside the sheath can also be filled with lubrication oil or insulation to protect the conductors.

• It can be divided in 2 category which are inner sheath (bedding) and outer sheath.

Multiple Choice

What is the main function of cable insulator?

• To transmit electrical voltage from one point to another.

• To resist the electrical voltage flow through the wire cable.

• To prevent the electrical voltage from leaking out of the cable.

• To provide support for the wire cable.

Multiple Choice

What is the suitable material used for some part of the wire cable?

• Conductor - Rubber

• Insulator - PVC

• Sheathing - Copper

Multiple Select

Which sentence is true about Inner sheath ?

• Carry power from one end to the other

• Mostly used in multi-core cable

• Provide bedding to armour or braid

• Mainly made up of PVC or Rubber

Multiple Select

Which sentence is true about outer sheath?

• Made up of PVC or Rubber

• Outermost cover of the cable.

• Provide from external resistance such as mechanical, weather, chemical and electrical.

• Provide bedding to armour or braid

Reaction of cables to a fire

• Cables are backbone of electrical power and communication system.

• It is important to test its reaction towards the fire in order to determine their contribution might affect the fire growth or safe evacuation.

• BASEC is a specific party who is appointed to develop more reliable and consistent test in this field.

The test of the wire cable toward a fire is based on its 3 main technical group

1. Reaction to fire

• The test is conducted in order to see how does the cable react when it is exposed to fire.

• They are usually performed on a non-energized cable with a gas burner applied to the cable for a fixed period of time

• Measurement criteria are usually based around linear spread of burning, or the emission of gases or smoke from the cable

2.Fire resistance (Circuit Integrity)

• Circuit integrity tests are generally performed on an energized cable at maximum operating voltage using a ribbon burner.

• Measurement criteria are usually based on how long the cable can continue to operate for a specific time period without failure.

3.Material Properties

• It is carried out on a small length of cable or piece of material

• Measurement criteria are usually based on physical properties or chemical measurements

• Tests include smoke emission (3 m cube test, IEC 60134), corrosive and acidic gas emission or halogen content (tube furnace tests, IEC 60754), carried out on a small length of cable or piece of material

Multiple Select

What is 3 main technical group to test wire cable interaction towards fire?

• Smoke emission

• Reaction to fire

• Material properties

• Fire resistance

Multiple Choice

What is BASEC stand for?

• British appliance service for cable

• British approval service for cable

• British authorization service for cable

• British approval system for cable

Multiple Choice

From the answer below, which is related to the reaction to fire group?

• To determine the emission of hazardous smoke during burning.

• To measure the efficiency of operating wire cable during burning.

• To measure the propagation of fire along the cable.

Multiple Select

Why cable sockets need to be securely attached and locked on to the terminal?

• To avoid wire cable from being loose and lead to short circuit.

• To prevent arcing and overheating surround the wire cable which lead to a fire.

• To avoid from direct contact to the user which may lead to electrocution.

End of slides

Thank you.