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ahmed osama
Joined: 18 Jul 2004
Posts: 258
Helped: 1
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 20 Aug 2006 19:04 Copper Wire & Aluminium Wire ??? |
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hi all
in some countries , the code saying that al. wire used in underground cables but the wires inside building must be copper
So i am asking why , what the diff. between the al. & copper wire??
what i know that the al wire have dia. greater than the copper wire at the same current
i want to know what about the safety & aging ..etc??
thx all
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flatulent
Joined: 19 Jul 2002
Posts: 4879
Helped: 295
Location: Middle Earth
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| 20 Aug 2006 19:14 Re: Copper Wire & Aluminium Wire ??? |
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| The problem comes from the hardware inside buildings. They usually have copper contacts with the wiring. The bimetal contacts can cause heat and then fires.
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sigint
Joined: 01 Jan 1970
Posts: 1049
Helped: 14
Location: State of total unemployment
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| 22 Aug 2006 7:31 Re: Copper Wire & Aluminium Wire ??? |
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To expand on Flatulent's comments, aluminum used with compression fittings is not safe, thermal expansion and subsequent contraction leaves voids in the connection that immediately oxidize - over time this repeated occurance creates a high resistance and resultant heat then sometimes fire - aluminum was used in residential housing for a short while with often disasterous results. It is now used in some applications with many precautions, making it too expensive for everyday use in buildings.
SiGiNT
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funster
Joined: 30 Jun 2005
Posts: 235
Helped: 12
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| 09 Sep 2006 15:04 Re: Copper Wire & Aluminium Wire ??? |
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with same diameter, a copper wire has much less resistance than al. wire,
at the same time, copper's melting point is high than al.
so I think that's the reason.
best regards
| ahmed osama wrote: |
hi all
in some countries , the code saying that al. wire used in underground cables but the wires inside building must be copper
So i am asking why , what the diff. between the al. & copper wire??
what i know that the al wire have dia. greater than the copper wire at the same current
i want to know what about the safety & aging ..etc??
thx all |
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aland
Joined: 09 Sep 2006
Posts: 15
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| 09 Sep 2006 15:59 Re: Copper Wire & Aluminium Wire ??? |
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Size for size Cu beats Al any day. But weight for weight Al beats Cu. Thats why aerial conductors are Al -usually with a steel core so that it doesn't stretch under its own weight as its very ductile.
Al problem is that it oxidises very quickly, so joints are a big problem. Even the Al-Cu joint has to be set up correctly if exposed to weather, the Cu wire *must* be placed below the Al *or* Cu salts from corrosion will eat into the Al.
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gizzmo
Joined: 03 Dec 2005
Posts: 8
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| 17 Sep 2006 13:44 Re: Copper Wire & Aluminium Wire ??? |
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| I owned a house that had aluminum wiring. It's possible to mix copper and al on a branch circuit, but you must use gray anti-oxidant paste + Cu-Al marrette connectors to avoid the risk of a house fire. The marrette connectors are very hard to find in the marketplace now, so it is best to avoid aluminum altogether, as it will eventually have to meet copper somewhere !
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