WIRE

A wire is a single rod of metal which can be used for electric power transmission(e.g:- in power line and in Domestic wiring),for signals transmission(e.g:-in telecommunication) and to bear mechanical loads(e.g:-In case of a elevator wire)
or
A wire is a single conductor. It may be with solid(Class 1), Stranded(Class 2), or flexible(class 5) conductor.

What materials are used to make wires?

For electric power transmission we use mainly two types of conductor for wire formation
1-Copper(Cu)
2-Aluminum(Al)

Copper(Cu)

It has high conductivity, high tensile strength and high cost as compare to Aluminum. Most of the signal cable are copper cable due to its good conductivity

Aluminum(Al)

It has low conductivity, low tensile strength and low cost. Aluminum is mostly use in the form of cable for power transmission due to its low cost.

physical forms of conductor

physical forms of conductor in the wire may be a solid conductor(i.e a single solid conducting wire) or it may be strand conductor(or multi-strand)
Strand meaning :-A single piece of cotton, hair, thread.
Therefore multi-strand wire are those wire in which there are multiple wire of very small diameter are present.

According to the flexibility of the wire conductors we can divided it into 4 classes

Class 1: Solid conductor

Class 2: Class 2 are stranded conductors and Class 2 is used in cases where the installation is fixed.

Class 5: Class 5 having more strand's of thinner dia than class 2 and it is used where more flexibility is desirable. Class 5 is better conductor comparison to Class  2. 

Class 6: Extra flexible conductor Mostly used for cords and welding, etc.
So we can say that class 1 and class 2 are cables used for fixed installations, Whereas class 5 and class 6 are used where we need flexibility.
Normally our FR wire is belong to class 5.

More number of strands in a cable increase its flexibility, heat dissipation property of the cable by increasing the surface area of overall conductor in the contact of  surrounding environment. So more number of strands helps to maintain operating temperature.

Insulation

When we use wire for carrying the electric current we mostly provide an insulation the wire and there are different types of insulation which is use for a wire

PVC(Polyvinyl chloride)

PVC is mostly used for insulation of the cable because of its ease to use and widely available. It provide a better insulation but it easily catch fire and give a large amount of smoke, therefore PVC quality is improve and we get different version of PVC such as FR, FRLS, HFFR, etc.

What is the difference between FR and FRLS wires?

FLAME RETARDANT (FR)

Compared with normal PVC wire FR wire do not catch fire easily, But these wire emit smoke. As we know that in case of a fire accident a major cause of death is smoke so our scientist try our best to remove the smoke from wire therefore we have different types of wire for low smoke e.g FRLSH and FRZH

FLAME RETARDANT LOW SMOKE (FRLSH)

As compare to fire property FRLS is just like FR, But it emit low amount of smoke as compare to the FR.

Oxygen index of Normal PVC cable is about 25% while FRLS Industrial Cable have oxygen index of more than 29%(minimum)

 

FLAME RETARDANT ZERO HALOGEN (FRZH) / LOW SMOKE ZERO HALOGEN (LSZH) / HALOGEN FREE FLAME RETARDANT (HFFR)

It is better than FRLSH because here we get zero halogen from the smoke of LSZH as halogen is a toxic gas.

Wire gauge

Wire gauge is also a way of measurement of wire diameter.
AWG(American Wire Gauge), As the value of AWG is increase the diameter of wire is decrease. AWG comes in range of 0 to 40 normally.
10AWG=2.588mm
28AWG=0.321mm