Copper and aluminium reaction

[GreekIslandLover]

Hi all,

Got asked a question by a freind, and am looking for what you guys think.

He's putting something or other (12v - all the info given) outside in the garden and I gather it's aluminium cables somewhere along the line. I know there is a chemical reaction between the two metals, and his concern is that this will cause poor connections somewhere down the line. He's been on the web (groan) and found a product in the USA you smear on the terminations to stop this reaction and he was wondering what we do here. "Use copper cables and brass" was my answer.

So, on the very limited info above, is the chemical reaction really a problem? Should he be investigating products to import from the USA for a few garden lights (making an assumption based on garden and 12v)? Should he not worry? Should he skip it, and buy something with copper cables instead?

Have asked for more info on precisely what he's up to, but would appreciate your thoughts on the scant info I currently know.

 

[The Godfather]

Here's something I found on the net (excerpt).

Another issue is the joining of aluminum wire to copper wire. As aluminum and copper are dissimilar metals, galvanic corrosion can occur in the presence of an electrolyte and these connections can become unstable over time. Special connectors have been designed for the purpose of joining aluminum to copper wire, such as the Marrette No. 63 and No. 65 and the Ideal Twister No. 65. These twist-on wire connectors use a special antioxidant paste to prevent corrosion of the connection. Lug type connectors similar to those used for larger gauge aluminum-aluminum and aluminum-copper connections are now available for branch circuit size wiring. These would appear to make a more reliable connection on the aluminum wire with its higher coefficient of expansion than wire nut type connectors. These may have the same problem with enclosure space as the Copalum system (described under "Upgrading aluminum-wired homes"). It should be noted that a listed connector should always be used for connecting aluminum to copper wire.

Although aluminum wire smaller than 8AWG is not used in new house wiring, lots of aluminum wires are used all over North America. The larger sizes offer excellent options for terminations, since the most common termination in larger sizes is a dual-rated lug made of an aluminum alloy. Properly terminated aluminum wiring should be regarded as safe, since long-term installations have proven its reliability. Aluminum wire is often used in residential applications for service entrance and large branch circuit loads such as ranges and air-conditioning units.

The Godfather

 

[steptoe]

the reaction only occurs where oxygen is present, and IMO it would be very insignifigant in this case, tho, if you/he is very concerned then may I suggest some silicon grease as used on sat TV connections. (see link in relevant section).

I have used this/similar on many occasions with success.

an alternative I have also used is copaslip(copper grease) simply because I have it readily available in my garage.