Dissimilar metals

[ICE]

Copper and aluminum can't be in contact. The aluminum will degrade and it doesn't take that long to happen. The racking companies are reluctant to include that information in the installation instructions. I know that because I was tasked with approving the installation instructions prior to approving the racking for use in LA County.

The racking companies include the information but bury it and then it is a recommendation. The best place to include a note to keep copper away from the aluminum would be with the picture.


But that would be too prominent so it is a few pages later in a group of notes.


I have never understood the phobia about mentioning copper in contact with aluminum. It happens often... like almost every time.






Both of the pictures are wrong installations for more reasons that just the dissimilar metals.

 

[steveray]

Stainless and aluminum are bad together too...

 

[Paul Sweet]

It's OK for water to run over aluminum then onto copper, but water running over copper then onto aluminum will degrade the aluminum. If there is just a small area of copper relative to the aluminum (such as the bare end of an insulated conductor at a terminal) the degradation will be so slow it doesn't matter.

I expect the manufacturers make a big deal about it as a CYA measure.

 

[ICE]

I expect the manufacturers make a big deal about it as a CYA measure.

The manufacturers try their best to ignore it. I had to force them to include it in the installation instructions at all and then it is buried. Try to find it in any manufacturer's installation instructions. The one I posted is on page 45 of 50 and on a list of "recommendations". It is part of the requirements in the Standard UL2703.

I was a member of the panel that created UL2703. It was an eyeopener. I learned to not trust installation instructions and to be leery of NRTL Listings.