An interesting query!

There is a British Standard for lamp standards (EN 40??) so the strength should be the same.

I wonder whether it is a corrosion concern? If the hanging baskets are on a steel bracket, then it would tend to set up an electrolytic cell in which the lamp post would be the anode and would corrode in preference to the steel.

If its a dissimilar metal thing, surely a rubber strip between the 2 metals would suffice.

Hang the baskets up!

If it is dissimilar metals it is relatively easy to arrange galvanic isolation, as others have suggested.

It might be fatigue concern - some people are overly phobic about aluminium and fatigue, and there have been streetlight failures due to fatigue (though I only know of steel or iron ones). However, if it's a newer housing area, presumably with relatively recent posts, the manufacturer should be able to quantify fatigue performance. Some people think that regarding fatigue steel=good and aluminium=bad, but neither one of those is necessarily so.

[Fatigue: Low grade steels exhibit a fatigue plateau - below a certain stress range steel won't fatigue ever. Aluminium does not plateau, it always fatigues to some degree regardless of the smallness of the stress range. This makes some people think fatigue in aluminium is automatically a bigger problem than it is in steel. However, higher performance steels don't necessarily exhibit the plateau, various manufacturing processes or detailing eliminate the plateau, and if properly considered the fact that fatigue damage occurs is just not a problem - there's no practical difference between never fatigue, and fatiguing at a rate that will fail in 10,000 years.]

It’s all ‘good stuff and the problems associated with dissimilar metal corrosion/’galvanic action’ is not insurmountable.

Imwaldra, rather than both you and us continuing to speculate, I would suggest that your best approach would be for you to speak with the appropriate person at the LA involved to try and establish the reasoning behind the ‘ban’ and then try to find a mutually agreeable proposal to overcome it. With the best will in the world, until you have an idea of the reasoning behind the ban, you are unlikely to find the answer here.

let us know how you get on.

Thanks for your comments. Before posting my query, I had thought about galvanic corrosion and decided that a short section of insulating material should solve that. I also did a web search and came up with nothing - hence the reason for posting, asking if anyone knew of guidance.

As the combined wisdom of Forum users has come up with none, I will now contact the Council - I just wanted to be thoroughly prepared before I did so.

On the other hand it should be possible to design a suitable bracket from a polymer and design it so that the metal fixings for that could not be connected by a conducting path (moisture etc) to the lamp standard.

Jane

In the fifties many ships were built of steel with aluminium superstructures to save weight high in the structure. One such ship I sailed on was Katsina Palm in about 1972, ship was then some 15 years old.

Accordingly there was a dissimilar metals interface around the whole superstructure. Of course, it is never wet at sea .... !!