question

Peter Buijs - NL avatar image
Peter Buijs - NL asked

Tinned copper

In environments with high humidity e.g. on a sailing vessel at sea we see a lot of corrosion at connections with metals with dissimilar potential.

In the presentation of the Victron fuse holders there is mentioned tinned copper bars with stainlesssteel (hope it is A4) bolts and nuts (rings)

These are materials with quite a different potential, isn't better to use tinned brass nuts bolts and rings.

fuses
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Hi @Peter Buijs - NL

Where in the documentation are these materials mentioned?

As far as I know, Victron mainly uses plated (nickel?) brass for fasteners.

the cheaper ' Six-way fuse holder for Mega-fuse with busbar (250A) CIP050060000 uses zinc plate steel (8.8) fasteners.

in a marine environment I'd use a little bit of grease on all electrical connections to keep out moisture and oxygen.

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Peter Buijs - NL commented ·

Hi @Peter Buijs - NL

Ah...the busbars...didn't think of that.

I've checked the 250A busbar I have in stock, it's 304 bolts.

As long as u use some grease, you won't have any problems.

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1 Answer
Alexandra avatar image
Alexandra answered ·

@Peter Buijs - NL

https://captaincorrosion.com/galvanic-corrosion-simulator-engineering-edition/

Its a bit of a tough one to answer there. Yes there a difference, but is does depend on what grade stainless is used as to how high the dissimilar potential goes. The calculator above shows some grades have significantly lower potential differences.

The thing is though what also needs to be considered are the items being connected to the bus bars, what composition are those cable terminals or fuses depending on what you are using there?

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Alexandra avatar image Alexandra ♦ commented ·

I cannot comment on what grade stainless is used exactly

screenshot-20210423-225432.jpg

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Alexandra avatar image Alexandra ♦ commented ·

I imagine there was some research done on which ones were worse.

screenshot-20210423-230124.jpg

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Peter Buijs - NL avatar image Peter Buijs - NL commented ·

What I meant to say is:

A tinned copper bar with tinned yellow brass bolt, nuts and rings

maybe is a better idea than using stainless steel A4 (316) or A2 (304) bolts, nuts and rings.

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Alexandra avatar image Alexandra ♦ Peter Buijs - NL commented ·

@Peter Buijs - NL I hear what you are saying. I played some more with the simulator i linked there are some better combinations science wise on paper.

https://www.solarsailor.com/best-marine-busbar/ the tinned copper with stainless seems to be the standard where ever you look though.

There are other factors like industry standards, conductivity, cost of manufacture, end cost to user. Cost to the environment. So sometimes just a bit of electrical grease and some good old fashioned maintenance is really the way to go.

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