Reply #33: You can use dielectric coatings or fittings to bar the current [View All]

[AZCat]

A dielectric is any substance that is highly resistant to the flow of electric current. In plumbing, dielectric unions are used to change piping from iron to copper (and vice-versa). They contain plastic parts that prevent the two metals from touching. You can also use a metal that isn't "friendly" to either of the two metals. I think brass works for iron and copper.

This problem has been around ever since metal became common in construction. There was a period in the 1800's where lots of metal structures were failing and it took a while to understand the various causes, but they figured it out quite a while ago. Long enough that I think it would have been taken into consideration in the WTC construction.