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Use Of Aluminium In Underground Telephone Cables.

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oldmisery | 17:54 Sat 08th Dec 2012 | Science
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Is there any truth that aluminium was used as an alternative to copper to transmit domestic telephone messages ?

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.I'd be interested to know the answer:
Al is not that good a conductor - unlike Cu Ag Au


PP

OH who is ex BT says yes, in local distribution networks.
Yes it has been, it was cheaper and OK for voice... it's crap for broadband though.
Much of Milton Keynes telephone network was laid with aluminium. Chuck is correct, outside of voice, it's a problem
Aluminium is a good conductor. In fact by mass it is about twice as good as copper having 59 percent of the conductivity by volume but only 30 percent of the density.

It is used extensively for overhead power transmission for this reason as well as lower cost. It larger diameter also is beneficial for the reduction in corona discharge at high voltages.

However the tensile strength of aluminium is lower than copper. Large multistranded aluminium overhead cables are wound with a steel core to provide the strength.

The other disadvantage of the larger diameter for the same conductivity is the cost of insulation.
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Many thanks for the illuminating replies , it was intimated, after a poor reported speed on my fibre optic broadband installation, that there were error codes appearing on my line (possibly from interference internally/externally) resulting in a far lower expected speed to level out my broadband. A higher speeed could be attained only with far greater fluctuations so was unadvisable and pegged at 14mps. Also there was the likelihood of the distribution network containing aluminium increasing the chances of interference.
I heard (within the last coupe of years) that copper cable was being replaced by aluminium because of all the metal theft going on. Aluminium is worth much less than copper, and so is not so attractive to metal thieves - was the explanation.
During the 80s a mixture of copper and aluminium was used in electric cables because of the high cost of aluminium .

Other factors against aluminium are, it oxidises easily which causes difficulty when making conections, it can not be soldered easily , it is brittle
and because of the skin effect of AC any oxidation of exposed areas causes problems. Thats why it is useless for broadband transmission.

However because of its light weight it is sheathed and used for overhead power lines. If it wasn't used all the pylons would have to be much closer together. Another advantage, compared to copper it is much cheaper and
abundant throughout the world.

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