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topic 38265, p2

Why must Copper Bus Bar be Tin Plated?



1       2



A discussion started in 2005 & continuing through 2017

February 5, 2014

Q. Sir,

What is the effect of tin plating on the copper. Remember the skin effect current is passing through the outer surface of conductor. We have tin plating on the copper, now copper is the conductor. Tin has different resistance and copper has different resistance. Now my question is: tin will affect the total resistance of the copper bar because of tin plated on the copper? In this case copper resistance is affected or not.

Please give detailed answer.

Regards,
Jack

Jalal Maryland
Student - Duabi, UAE


February 2014

A. Hello Jack. Very high frequency currents do tend to travel on the "skin" of a conductor rather than through it's core. But the study of that phenomenon is an electrical engineering discipline which is a subject of greater depth than can be handled here, off-topic for this metal finishing site, and probably not what you were asking anyway :-)
I only mention it to not mislead people who may have found this page because of the search term "skin effect", which we are using in a different way than they might.

We are talking here about bus bars, and they are used for DC current or low frequency AC current, where the current flows through the bar, not on its skin. The resistance of a bus bar, and thus its current carrying capacity, are related to its resistivity as follows: Resistance = resistivity X length ÷ cross-sectional Area.

Since 99.9%+ percent of the cross sectional area of the bus bar is copper, the bus bar's current carrying capacity is not measurably increased or reduced by plating the bar with another material.

38265 bus bars

However, getting the current into and out of the bar requires that the contact faces be conductive rather than resistive, and silver or tin plating will do a better job than copper for the reasons already discussed on this page, offering a less oxidized skin. Remember that when you are calculating the resistance across the joint rather than along the length of the bar, per "Resistance = resistivity X length ÷ cross-sectional Area", now "A" is the cross sectional area of the joint and "length" is the thickness of the plating. So this piece of the Resistance is extremely minor because "length", the thickness of the plating, is next to nothing. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



February 12, 2014

Q. Ted,
If installing a tin or silver plated copper bus bar as a "bay" frame ground for terminating EQP grounds within the bay, is there a need to utilize No-Ox-Id between the EQP 6 AWG ground lead and the mounting surface position of the buss bar? If not, is it because the plating of the bus bar coupled with the fact that Telco sites are controlled environments negate the need to utilize No-Ox-Id?

Thanks

Antoino Randolph
- Trabuco Canyon California US


February 2014

A. Hi Antoino. I have a good deal of experience in electroplating shop environments, and a small amount as an amateur electrician. But I am not qualified to comment on codes or best practices in your field. All I can say is that, if you are not in a cleanroom environment (which might discourage use of compounds), and there is no other reason to specifically discourage joint compounds, it would seem that electrical joint compound is always a good idea.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



May 20, 2014

Q. Hello,

If you are using tin plated copper bus, is there any advantage to silver plating the connection point?

Thanks.

Paul Sauder
- Regina, SK, Canada


May 2014

A. Hi Paul. I doubt it, and I've never personally heard of it.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



Must we de-rate copper bus bar if we tin plate it?

August 19, 2014

Q. Hi,
We have 658HP VFD drive(415V/3ph/50Hz) & installed in factory where the surrounding is corrosive due to which the copper bus bar & DC bus plates are getting blacked. We are planning to do tinning to all copper bus bars & DC bus plates. So want to know whether to consider any de-rating of copper when tinning or other way is copper bus bar current capacity de-rate due to tinning?

Sayed Hassan
- Mumbai India


September 2014

A. Hi Sayed. I would not anticipate any need for de-rating based on my understanding of the situation. However, there still may be codes or "best practices" that I would not be aware of since large horsepower variable frequency drive installations are not my field.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


September 17, 2014

Q. I would like to know, is there any requirement for the copper bars in a busbars to be plated with Tin along the entire length as the bars are insulated with Epoxy, which is electrostatically deposited on to bare bars.

Bibin Joy
- Dubai, UAE


September 2014

A. Hi Bibin. I can't answer that question and I doubt that anyone can because you seem to be asking about job requirements or specification requirements rather than a technology question. But certainly I would expect an epoxy coating to deliver even better corrosion resistance than tin plating. Best of luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


September 27, 2014

A. Tin will actually slightly increase the conductivity of the buss bar because you are adding metal.
Conversely, powder coat is an insulator and will not let the buss bar dissipate The heat to the atmosphere as well.erature As the temp goes up, so does the resistance which will generate more heat. So, your operation will probably be less efficient.

James Watts
- Navarre, Florida



Conductivity of bus bar is too low

September 28, 2014

Q. Please, I need help regarding bus bar manufacture.
We are producing copper bus bar (OFE COPPER BUS BAR) but sometimes it comes with low electrical conductivity. WHAT CAN MAKE THIS CONDUCTIVITY LOW?

ahmed ismail farag
- RIYADH,ASIA,SAUDI ARABIA


September 2014

A. Hi Ahmed. Our focus is finishing and I know little about copper smelting. But the conductivity of copper declines drastically with even a very small amount of contamination because any impurity interrupts the travel of the free electrons. Are you absolutely sure the copper is electrolytically pure?

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



Can we use galvanized hardware to join copper bus bars

November 10, 2014

Q. Can we use galvanized steel to assemble the panel copper bus bars?

khaled abo talib
- riyadh, kingdom of saudia arabia


April 3, 2015

Q. An electroplating plant has bus-bars which carry up to 1000 A at 6 V dc. The surroundings are very wet with water and electrolyte. Should the bus bars be insulated and if so, why?

nurul syazmeen
- - melaka, malaysia


April 2015

A. Hi Nurul. No, the bus bars should not be insulated. But the bus bars are not the problem; the problem is that the surroundings are very wet, and you should examine carefully any assumptions about what conditions are unavoidable. Please see my article "Plating Shops for the New Millennium". Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



April 26, 2015

Q. Please, regarding manufacturing of tin plated copper bus bar: anyone can guide me to specification for electroplating of tin on copper?
Which specification can I follow? What is the minimum AND maximum tin thickness ON COPPER BUS BAR?

ahmed ismail
- riyadh-SAUDI ARABIA



July 31, 2015

Q. Sir,
I want your help.
At present we are facing problem of High temperature in our 6.6/11 KV Bus Bar Joint, CT Connection joints temperature is up to 120 °C
I want to know what best solution to avoid this is.

Thanks

Shekhar Mundhada
- Jamnagar, India


August 2015

A. Hi Shekhar. We have posted your inquiry and hopefully someone will help. My experience is in metal finishing, not switchgear design, although it sounds like the conductors are probably too small for the current they are carrying.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



August 21, 2015

Q. I am working on a lighting project that uses a 10 AWG equivalent round copper busbar for low voltage track lighting. The voltage is 12V AC or DC, and the maximum current through the system is 20 Amps.

The sections of the track are joined with spring-loaded blades that slide against the copper busbar, much like the typical track lighting interconnects you would see at Home Depot.

My questions are:

1. Do you think I need to plate the copper busbar to ensure connection reliability, or would bare copper by acceptable due to the low voltage and relatively low current?

2. If plating is necessary, would nickel plating perform reliably compared to tin plating? Our contract manufacturer already nickel plates many parts for aesthetic purposes, but they don't do tin plating. So nickel plating would be familiar to them, but I don't know if nickel plating has any significant disadvantages over tin plating.

Thanks!

Chris Ruhland
- Chicago, Illinois, USA


August 2015

A. Hi Chris. Again, I don't portray myself as an expert in such subjects by any means ... but I don't see any need to plate the copper. Make sure, of course, that you are using electrolytic grade copper as even a small amount of impurities has a devastating effect on electrical conductivity.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



December 1, 2015

Q. Whether tinned copper bus bars are required in a medium of SF6 gas. Whether the current carrying capacity gets de-rated in SF6 gas medium?

Manas Bhattacharjee
- New Delhi, India


38265-2
December 2015

A. Hi Manas. I know nothing of SF6 switchgear, but certainly any joints would seem to benefit from tin plating irrespective of what medium the joint is in, because you will not be manufacturing the copper and assembling the joint within an SF6 environment, but out in the open.

Please try to detail your actual situation rather than casting the proposition in the abstract with sentence fragments :-)
There would seem to be no air cooling within a pressurized SF6 environment, so presumably you must de-rate accordingly. Good luck!

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



December 22, 2015

Q. Dear All

I had a question, what grade of copper is being used and which will be the best?

Grade:
- ETP Grade - IS 613, BS 2871C-101 or
- DHP Grade - IS 2501-DHP, BS 2871C-106.

What is the main difference between both grades.
Which will be used in Bus ducts system and Panel boards ?
Please provide me with details.

Regards

Jaffer Saleem
bus bar manufacturer - Riyad, Saudi Arabia



Discoloration of tin plated bus before it's even used

January 18, 2016

Q. Why black colour marks are formed on the tin coated busbars of the new panel board which not yet charged?

Raviraj Channalli
automation - Bangalore, Karnataka, India



January 20, 2016

Q. I am struck in this situation, hope someone will extend a helping hand

A copper cable to be connected(either crimped/ soldered/ pressure/screw fitted) to stainless steel bus bar and the bus bar is to be connected to the power supply of 12 V DC.

38265-3a  38265-3b

Now I have the following queries:

1. Can a connection be possible from copper wire to Stainless steel bus bar ? If yes, what are the factors need to be considered ? Can copper wire be connected to copper coated stainless steel bus bar ?

2. What type of connection between copper wire and steel is feasible( crimping,clamping , screw etc).

3. In my case, coating of stainless steel with any metal will make the connection feasible? if possible also the electric transfer efficiency of the connection in various cases?

Thanks in advance...

Abhilash Mondrathi
- Coimbatore , Tamil Nadu, India


January 21, 2016

A. Good day Abhilash.

I think you should consider the current carrying capability of stainless vs. copper buss bar. The "electric transfer efficiency" of stainless is much lower than that of copper.
Connections can be clamped or bolted with the use of an oxide grease. They can also be clamped or bolted and soldered.
Hope this was helpful.

Regards,

Eric Bogner, Lab. Tech
Aerotek Mfg. Ltd. - Whitby, Ontario, Canada


January 22, 2016

Q. Coating the stainless steel bus bar with copper can solve the issue and establish an efficient power connection in my case?

Or plating of the bus bar with any metal will be helpful in my case?

Abhilash Mondrathi [returning]
- Coimbatore, Tamil Nadu, India


"No-Ox-Id" Compound

January 2016

A. Hi Abhilesh. I think that Eric was suggesting that stainless steel is not a very good bus bar substrate material -- it's current carrying capacity is only about 10% of the current carrying capacity of copper bus bar. But if you will be using stainless steel anyway, yes, it must be plated.

Copper plating should be sufficient for a 12 V power supply situation if the connection is tightly bolted, and a compound is used. But copper plating the bus bar, and then silver plating all of the contact surfaces would be better. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



January 24, 2016

Q. Hi,

Two questions,
1. Is is advisable to place a bimetallic washer in between a tinned copper and tinned aluminum termination of an electrical joint?
2. We always find some white powder over the tinned copper lugs. It is actually a Cu-Al joint? What and why is that white powder present there?

Please answer as I didn't find any answers so far.

Rahul kumar
- Chennai, tamil nadu,India



February 6, 2016

Q. Hello Sir,

We are using the copper bus bars with Tin plating (8 to 10 microns thickness). Some of the bus bars are Silver plated. These silver plated bus bars are oxidized (light black shades). So which type of solvent can be used for cleaning the black shades? Can you please suggest the solvent?

RC murthy.
- Hyderabad, Telangana, India.


February 2016

A. Hi Murthy. You're the second person to ask that this week, and my answer until I hear otherwise is that I don't know why everyday silver polish (used for flatware) could not do this job. If you google "MSDS silver polish" you will see lists of important ingredients. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



February 11, 2016

Q. Hi,

I have question about oxygen free copper, specifically about C10100 (Cu-OFE) and C10300 (Cu-PHC) ? Do they need to coated/plated (tin,nickel ...) to prevent oxidation? some sources state they don't.

Ivan Barbaric
- Zagreb, Grad Zagreb, Croatia


February 2016

A. Hi Ivan. High purity copper is quite corrosion resistant, and I'm quite familiar with applications where bus bar is not tinned. But it seems that it would depend both on the specific application and any standard codes that apply. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


38265extA

38265extB
February 18, 2016

A. This post is in response to the many questions regarding bus bars and which type of plating is best for the application.

I have worked for several large electrical equipment manufacturers over the years and there is no simple answer to which type of plating is best; however, there are only two which are exclusively accepted for electrical distribution: tin and silver.

Electrical equipment is installed indoors and outdoors and subject to moisture, salts, and reactive atmospheres; so, many years have been devoted to failure and cost analysis, and a lot of trial & error. Each has its merits and shortcomings and so knowing the environment in which the equipment is to be installed is of paramount importance.

I would suggest reading Data Bulletin 0100DB0401 "Electrical Equipment and Components in Adverse/Corrosive
Environments" published by Square D =>
It is a comprehensive examination regarding choice of plating materials and would likely answer many of your readers questions.

Another document worth mentioning is Data Bulletin 0108DB0602, "Thermal Aging Study of Tin Plating on Aluminum" =>

Most of your major manufacturers have tomes of white papers and publications regarding electrical equipment design and failure analysis and offer a wealth of information at the click of a button.

Regards,

Scott S [last name deleted for privacy by Editor]
Large Manufacturer - Austin, Texas


February 20, 2016

A shop dating back to WWII that I worked at put a sheet of aluminum foil between the copper layers of bolted joints.
It seemed to work quite well and was certainly low cost.

James Watts
- Navarre, Florida


February 2016

thumbs up signThanks Scott!

Very interesting, James, but I don't understand what that is supposed to do or how it's supposed to do it :-)

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



July 23, 2016

Q. Please, what does it take to De-oxidise Bus bars and what are the steps to do it?

Charles Emmanuel Ngozi
- Lagos Nigeria


July 2016

A. Hi Charles. Although "De-oxidize bus bars" means "remove oxidation from bus bars", it may not be possible for anyone to answer that question except the customer who requested it :-(

It MIGHT mean lightly sand the joint area and apply anti-oxidation compound, but it might not. We'd need to see it in context.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


Black-green deposit on automotive copper terminals

September 27, 2016

Q. We are facing a problem in car head light switch. There is blackish green deposition on the copper terminals (only the terminals connected to battery ground, the rest are OK). During EDX analysis of copper we observed the deposition of potassium and sulfur. Can there elements come from battery or is this related to environment or something other. Please help.

Dheerendra Singh
Automotive (car) switches manufacturer - Gurgaon , Haryana , India


September 29, 2016

A. That sounds like a reaction with pollutants in the air, likely SO2. "Blackish green" sounds like a mixture of CuS and other Cu compounds.

How's your local air quality? Perhaps you could install some kind of air filter.

dave wichern
Dave Wichern
Consultant - The Bronx, New York


October 9, 2016

Q. Thank you Mr. Dave
I also think same this is like CuS, but this deposition is only on three terminal rest are OK, we have received almost 50 defective parts all have same pattern only three terminals which are connected to the battery ground have the deposition , if the cause is polluted air it should be on entire all Cu terminals.

Dheerendra Singh [returning]
Automotive (car) switches manufacturer - Gurgaon , Haryana , India


December 19, 2016

Q. Good Morning all!

Dear sir,

I have a doubt which type of insulation we have to provide in tinned copper busbar cutting edges whether we have to do tin coating again?

Please give a suggestion.

Regards

Sriram R.
electrical Industries - Muscat, seeb, oman


December 2016

A. Hi Sriram. It is possible that a given customer spec or industry standard requires replating of the ends. If you find no such spec, I guess my feeling would be that if only the contact ends of the bar are tin plated, there would not seem to be any reasonable need for plating the cut ends; but if the whole bar is tin covered end-to-end, and you have now exposed copper by cutting it, aesthetics or the possibility of galvanic corrosion might necessitate plating of the ends depending on the circumstances.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


December 20, 2016

Q. Dear sir,

Thanks for the reply.
Sometimes it may not be possible to re-Tin busbar edges. I think there is no tin sprays are available in the market. Whether zinc coating is advisable for the edges?

Regards,

Sriram R. [returning]
electrical Industries - Muscat, seeb, oman


December 2016

A. Hi again. Sorry, but zinc plating of the cut ends sounds to me like a terrible idea.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


January 1, 2017

A. Dheerendra,
An undercharged battery can cause this. I would suggest a protective coating for the Cu.
Sriram,
The thing to do, in my humble opinion, is to cut the bus bars and then tin them. The bus bars should be completely coated.

blake kneedler
Blake Kneedler
Feather Hollow Eng.
Stockton, California



December 27, 2016

Q. Are there any methods available for tin plating over aluminium bars by spray plating method??

dhanus mohan
- Coimbatore,Tamilnadu,India



February 20, 2017

? Why would you need tin plating if there is the use of a suitable oxide-inhibiting compound between the joints to stop oxidation? Yes, the exposed copper will discolor; however, that won't limit its ability to conduct 600 A or greater.

keith Gosh
N/A - Boulder, Colorado USA



June 15, 2017

Q. If said Tinning will not increasing Ampere rating, some cases using Uniniven cables for higher current applications please clarify

HARSHA KUMAR
Powertech Industires - Ajman UAE


June 2017

? Hi cousin Harsha. Google comes up empty for "Uniniven" -- perhaps it's a typo.
This thread now contains more than 80 entries; to further 'clarify' the claim that tinning improves the reliability of an electrical joint but does not necessarily increase its ampacity, we would need you to take a couple of paragraphs to carefully detail your situation so we can present a detailed defense of what has been claimed. Otherwise, I don't know how to 'clarify' something which I've already repeatedly tried to make clear, when I don't even understand your posting :-(
Thanks for your understanding.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



November 9, 2017

Q. Dear Sir,

As you said low frequency current will not pass on outer surface of the conductor rather its core. My question is we are making tin coating on the copper conductor, while making the joints(as you explained in drawing) surface of two tin material is touching if this is the case current is flowing on the surface of the conductor. kindly brief me if I am wrong (resistance of tin and copper is different, tin will affect current carrying capacity of copper) .

Regards,

Jack

Jalal Mohamed
- Dubai, UAE


November 2017

A. Hello Jack. Please imagine for a moment that you were trying to connect copper bus bars to carry current, but someone had inadvertently painted those bus bars, so they had a layer of paint on them which was interfering with a proper connection. You would need to remove that paint in order to make a good connection.

All metals except precious metals like gold & platinum react with the oxygen in the air to "paint themselves" with non-conductive oxide (tarnish) surfaces. Depending on which metal we're speaking of, this naturally forming oxide can be thick, highly insulative, and always a serious problem; aluminum is an example of that, and it can never be used as a contact surface. Sometimes the naturally forming oxide/tarnish is quite thin and not a problem for most circuits; for example, nickel is a fine contact surface almost all the time because it's oxide/tarnish is very thin; but extremely low power & low voltage digital circuits must be gold plated so there is absolutely no oxide (tarnish). One reason that copper is plated with tin is because the oxide/tarnish which forms on tin is not as insulative and problematical as the oxide/tarnish which forms on copper. So it is not the case that the current flows only on the tin surface, but that it can easily flow into and through the copper core.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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