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coopec43 · 27-03-2021, 02:49

I need a couple of bus bars.

I thought they were always copper but these days aluminum is taking over. I have plenty of aluminum (and heavy nylon sheet 10mm) but with aluminum I'd worry about corrosion.

I have plenty of heavy SS flat bar around 6-8mm thick. Is there a reason why I can't use that? (I know SS does not have the conductivity of copper so it will have to be heavier or alternatively have a lower max loading)

Negative Bus Bar 4 Stud Stainless Steel Marine or Automotive 210 Amp - Free Post

Negative Bus Bar 4 Stud Stainless Steel Marine or Automotive 210 Amp - Free Post.

4 STUD BUS BAR

NUMBER OF TERMINALS: 4
3 X 10MM STUDS (65 AMP PER CIRCUIT)
1 X 6MM STUD

TERMINAL MATERIAL: STAINLESS STEEL
BASE MATERIAL: GLASS FILLED NYLON
WEIGHT: 180 GRAMS
COLOUR: BLACK BASE
POWER RATING: 210 AMP

https://www.ebay.com.au/itm/Negative...frcectupt=true

**Wotname** · 27-03-2021, 03:48

Well SS is at least 30 times higher resistance than copper
https://www.thoughtco.com/table-of-e...ctivity-608499

Copper is easy enough to get
https://www.ebay.com.au/itm/1pcs-99-...Cclp%3A2334524

coopec43 · 27-03-2021, 03:58

Quote:

Originally Posted by Wotname

Well SS is at least 30 times higher resistance than copper
https://www.thoughtco.com/table-of-e...ctivity-608499

Copper is easy enough to get
https://www.ebay.com.au/itm/1pcs-99-...Cclp%3A2334524

I looked at the price of copper flat bar on eBay and wondered how much I'd be saving.

But this is a horrendous price as far as I'm concerned and that's what got me thinking of DIY bus bar. I wouldn't need anything like 210A

**Wotname** · 27-03-2021, 04:10

Quote:

Originally Posted by coopec43

I looked at the price of copper flat bar on eBay and wondered how much I'd be saving.

But this is a horrendous price as far as I'm concerned and that's what got me thinking of DIY bus bar. I wouldn't need anything like 210A

I guess it depends on the anticipated loads on the proposed bus bar and whether you can accept the voltage drops in question. If the majority current occurs between lugs clamped under one post, the material of the bar is less important however if the majority current is required to be carried by the bar, you should do the calculations carefully.

coopec43 · 27-03-2021, 04:23

Wotname

This looks reasonably priced and I think 100A is more than I would ever use. Right now I only need it for the Solar panel installation.

https://www.ebay.com.au/itm/Buss-Bar....c101195.m1851

**Wotname** · 27-03-2021, 04:30

How many terminations are anticipated and what is the current load of each?

Spot · 27-03-2021, 04:34

The bar is the conductor and the run is the distance between the washers on the lugs. I don't think you'll have an issue replicating that with 6 or 8mm bar which would have 4-6x the cross sectional area of the one shown in the pic. There is probably a point where intact stainless will outperform corroded copper. For me the downside would be spending all day long making one and not liking how it looks versus buying one for a few dollars.

coopec43 · 27-03-2021, 04:46

Quote:

Originally Posted by Wotname

How many terminations are anticipated and what is the current load of each?

That's a tough one.

The water maker will be 240V 8A and will work off the inverter. How do I earth the inverter? (That's something to think about)

Back to your original question. I have negative and positive bus bars on the house bank so it is only the starting bank (24V) I am thinking about. Of course the starter will work from the battery terminals. Charging the starter bank will have to be via battery terminals.

Now you've got me thinking maybe I should use these?

RaymondR · 27-03-2021, 10:41

I expanded my solar farm 3-4 years ago and the wiring was such a spaghetti like mess I cut a lot of it back and installed aluminium bus bars. Used a corrosion inhibitor paste under the terminals and blind riveted them to the bars. Last corrosion check was a few weeks ago and no corrosion found.

Currently I am attempting to salvage a lithium battery and when I removed the case top found that the alloy cell terminals are connected with copper bars with a corrosion inhibiting paste. Since these things are predicted to last ten or so years copper on alloy with paste appears to be becoming an accepted practice.

seandepagnier · 27-03-2021, 10:51

I have used aluminum but keep in mind that the contact between aluminum and copper is always difficult. This is also because of temperature changes can loosen it up with different temperature expansion coefficients.

better use copper or brass

**Wotname** · 27-03-2021, 14:37

FWIW, tinned coper terminals attached to aluminium airframes are problematic but commonly done with mitigating techniques - bimetal sacrificial washers (cu/al washers) either side of the terminal and coating with a waterproof varnish etc.

smac999 · 27-03-2021, 16:29

aluminum bus bas? they may look like alum but they are normally tin covered copper.

defiantly don't use SS

Frankly · 27-03-2021, 17:16

Drilling and tapping SS is typically not a fun exercise. Aluminum oxide forms on raw aluminum in hours, you can pretty easily tin copper and silver plating is even better. Just seems like a bad corner to cut, electrical requirements typically grow with time not shrink.

Frankly

CassidyNZ · 27-03-2021, 17:20

Quote:

Originally Posted by smac999

defiantly don't use SS

Please help me understand why not.

Whilst I understand the concept of resistance and resistivity, the difference between copper and any other metal is surely important when it’s through a wire (thin and long). But a bus bar is a short, fat block of metal which negates the importance of resistance/resistivity to a large degree.

The reason I ask is because a decade ago, I made two bus bars from 13mm thick 316 SS with eight 10mm SS studs tapped and screwed into them and tig-welded on the back. These have been the basis of my +ve and -ve sides of my whole electrical system since then. I’ve never experienced a single issue with them. By contrast the ones I removed were copper, corroded, green and must have had huge resistance because my electrics worked (or not) on a totally random cycle.

What should I know that I apparently don’t?

What I do know is that if you connect one of my bus bars to +ve 220v and hold it in one hand then grab the -ve in the other hand, you probably won’t notice the higher resistance