Alloy 110 Copper bus bar corrosion

[biggeorgetechnical]

We have been using alloy 110 copper for a ground bus bar in some of our equipment. In this case, the bus bar is drilled and tapped, and all the ground wiring in the cabinet lands at the bus bar. We currently have 24 wires, each with a separate AMP ring lug. This ties all the assorted ground circuitry to a single point. Anyway, this leads to my question:

One of my co-workers chose to change the alloy 110 copper by having it Electroless Nickel Plated. What benefit would this bring?

I would like to ask some of the experts to help me understand what benefits would be realized by this change.

Thanks,

George

 

[EdStainless]

Is the buss corroding?
Only at the lugs, or all over?
Are the luggs corroding?

I don't like tapping buss, I prefer through bolted connections. We always used brass or bronze hardware, no steel allowed.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[kenvlach]

"One of my co-workers chose to change the alloy 110 copper by having it Electroless Nickel Plated. What benefit would this bring?"

1. Provide employment to the EN plater.
2. Protect threaded holes from wear (off course, the holes must be tapped oversize to allow for the plating).
3. Provide heat. The electrical conductivity of EN is about 8% that of Cu, so passing a little current through will create ohmic heating to prevent condensation.
4. Protect against some types of corrosion.
Example: If you regularly wash or submerse the electrical panel in saltwater, any Cu-containing runoff will corrode nearby aluminum. The EN plating will stop this.

George, you really haven't given us much info except that by posting in this forum, corrosion must be an issue. What is the environment?

Plus, I would worry about UL & NEC issues with a low-conductivity plating on the copper. Also, no mention of plated bus bar in ASTM B187.

P.S. I've EN-plated Cu & Al bus bar & also steel pipe for use as cathodes & electrodes over electrocleaning, plating & anodizing tanks. But, in each case, there was a specific corrosion problem or need to avoid copper contamination of a solution below.

 

[biggeorgetechnical]

Hi kenvlach,

The environment of the equipment is electrical test equipment. I had not been advised there was corrosion going on inside the equipment. These units are not rated in any way for wash-down or submersion in salt water. They are High Voltage impulse and DC High potential sources, with microprocessor controls. They range in size from small suitcase size, to refrigerator size.

All are powered by single phase 115Vac or 230Vac 50/60Hz


I asked my co-worker what the benefit was and here is his response: "Pacifies the copper surface - reduces corrosion of the copper especially at the ring lugs."

Regardsing the NEC issue with plated bus bar, any advice would be happily accepted.

George

 

[kenvlach]

Is this environmental testing, with the electrical inside a condensing humidity?

I was rather facetious with "wash-down or submersion in salt water." But, sometimes nasty environments like food processing plants, small ships, etc., can be corrosive toward copper -- get blueish corrosion.

Nickel plating for electrical purposes is mostly performed to provide good contact or solderability to aluminum, stainless steel, titanium, etc. It would also minimize the galvanic corrosion of aluminum or steel vs. copper if moisture is present.

Surely you know a lot more about electrical codes than do I. Codes are rather strict about allowed materials -- any alteration to equipment may need qualification testing. Have only seen silver- and tin-plated bus bar. A quick search found
"ANSI C37.20 alternatively permits a temperature rise of 65°C above a maximum ambient of 40°C, provided that silver-plated (or acceptable alternative) bolted terminations are used. If not, a temperature rise of 30°C is allowed."
-- As nickel is relatively low conductivity, and forms a resistive oxide over time & if heated, I would not consider it an acceptable alternative, except in special circumstances. E.g., the tips of aluminum lightning rods are nickel-plated.

Is any corrosion occurring? Aren't the connecting lugs made of copper or similar (brass or high-copper bronze? As mentioned above, passive usually means oxidized = trouble for electrical connections, where 'nobility' of the metals is preferable.

 

[EdStainless]

Are you sure that there is steel hardware being used? This is a no-no.
We used to tin (well actually lead) coat bus for some protection.
Ken is right, You will be screwing up the electrical conductivity and you may inadvertantly cause corrosion of other Cu parts because the EN is too noble.

Unless you are having corrosion now that is leading to failures LEAVE IT ALONE.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[stevenal]

If these are ground connections, they only carry current during fault conditions. Any heating effect will only occur then, and only last until overcurrent protection operates. If corrsion is an issue, tin plating is what you want, not nickle. If this is inside a piece of equipment, NEC only applies to the extent that it should be listed. Probably needs to be relisted if it is changed.

 

[biggeorgetechnical]

EdStainless,

What would the no-no be for stainless steel, with 110 copper hardware be?

George

 

[EdStainless]

Very different coef of expansion and electrochemical behavior. Stainless also has poor thermal and electrical conductivity. We always used SiBronze hardware.
If it is working I guess it is fine. The risk is that with moisture you will get preferential corrosion of the Cu which will weaken the contact.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm