Which one is better as electric wire? Aluminum or copper?

Aluminum has better conductivity than copper (less resistance)

Copper has better mechanical properties (ie strength, flexibility) so we prefer copper wires.

Aluminum and

copper are

both very

good electrical

conductors.

Aluminum is

less

expensive

and lighter in

weight, and is

preferred in

higher voltage

industrial/

utility

applications.

But in

residential

applications,

copper is

preferred.

The reason

for this has to

do with two

metallurgical

properties of

aluminum.

First,

aluminum

corrodes, and

the corroded

aluminum is an

insulator.

Unfortunately,

aluminum

corrodes very

quickly, and

the corrosion

is not visibly

obvious. As a

result.

corrosion can

be present in

a connection

involving

aluminum

conductors,

and this

corrosion can

lead to

localized

heating in the

connection.

The other

problem is

'cold flow' -

specifically,

that when

aluminum is

placed under

pressure, it

will gradually

conform to

whatever

physical

constraint

caused that

pressure in a

way that leads

to a reduction

in pressure.

When

connections

are made to

aluminum

conductors,

this

characteristic

causes those

connections to

gradually

loosen over

time as the

aluminum

'flows' out of

the joint.

When

aluminum is

used in

industrial or

utility

applications,

special

connectors

are used that

incorporate

springs that

maintain

clamping

pressure on

the connection

in spite of the

tendency of

the aluminum

to 'flow'. In

addition, a

conductive

grease,

basically high-

quality

petroleum-

based grease

containing fine

particles of

zinc is use in

the

connection.

The zinc

particles

pierce through

the surface

corrosion on

the aluminum

to assure that

the connection

is electrically

sound.

Unfortunately,

these

techniques

aren't very

practical in

residential

wiring

applications.

Hence. most

building codes

discourage

the use of

aluminum

wiring in

homes.

Take care