Tin plated copper ground bus

[LMAO]

we mount a tin plated copper ground bus bar in our electrical enclosures for customer connections. The bus bar is tin plated but process requires tin plating to be performed before holes are punched. But what if the bus bar is plated after holes are punched in? Obviously tin is not as conductive as copper (almost 10 times the resistivity); will that make the ground bus not usable? We have received a batch of these and this is the case.

Thanks,

 

[ActionDave]

As far as I know the answer would be, no. Tin plated copper is very common and even at ten times the resistance it's still got to be conductive enough to do the job.

 

[zog]

The plating thickness is so small you would not see a difference. The tin plating prevents copper oxide from forming which has very high resistance.

 

[jim dungar]

The holes are not really part of the conductive path. The surface of the bar, the contact area, is always tinplated regardless of the timing of the hole punching isn't it?

 

[LMAO]

The holes are not really part of the conductive path. The surface of the bar, the contact area, is always tinplated regardless of the timing of the hole punching isn't it?

I understand that tin does not really affect the overall conductivity of bus bar but if bus bar is entirely covered in tin does not that make it difficult for the ground cable lug to make good electrical connection with bus bar? Wouldn't tin act as an insulator?

 

[GoldDigger]

I understand that tin does not really affect the overall conductivity of bus bar but if bus bar is entirely covered in tin does not that make it difficult for the ground cable lug to make good electrical connection with bus bar? Wouldn't tin act as an insulator?

Even if it has a bulk resistivity ten times that of copper, as already stated the resistance of a thin tin layer between the lug and the bus bar will not make any significant difference. Instead the greater contact area (given that tiny irregularities get crushed out) and the more reliable contact (no insulating oxide layer that has to be broken down by a voltage difference) more than make up for the increase.

An insulator has resistivity quadrillions (10¹²) of times greater than a conductor.

From https://www.quora.com/Whats-the-difference-between-a-conductor-and-an-insulator

Examples:

Graphene resitivity = 1.0x10^-8 best conductor

Silver 1.59x10^-8 best common metal but very expensive

Copper 1.686x10^-8 most popular electrical conductor relatively cheap

Alum 2.82x10^-8 half as good as silver

Iron 1x10^-7 you think of it as a conductor, but not used much as a primary conductor in circuits; conducts 1/6th as well as copper

...

Sea water 2x10^-1 if asked most people would say this is a conductor, but its 10 million times less conductive than copper.

Dry Wood 1.3x10^14 you might consider a good insulator a thousand billion billion times less conductive than copper.

Teflon 1x10^23 one of the best insulators, a billion times better than wood.

 

[Bugman1400]

Is this tin plating or silver plating? I've silver plated a ton of bus bars and terminal lugs in the field with a plating kit but, never tin.

 

[petersonra]

Is this tin plating or silver plating? I've silver plated a ton of bus bars and terminal lugs in the field with a plating kit but, never tin.

I don't think you can do them in the field but you can buy them that way

 

[K8MHZ]

Never mind.

 

[ActionDave]

I understand that tin does not really affect the overall conductivity of bus bar but if bus bar is entirely covered in tin does not that make it difficult for the ground cable lug to make good electrical connection with bus bar? Wouldn't tin act as an insulator?

Absolutely not. The wackiest, over the top grounding I have ever done is on cell sites. They have a set of specs that would choke a goat and they use tinned copper for everything. If there were any reason to not use it they wouldn't and the fact that they do use it answers the question for me.

 

[infinity]

I would assume that it was silver plated unless told otherwise.

 

[jim dungar]

Wouldn't tin act as an insulator?

Definitely not.
Almost every panelboard built by Square D, over the past 60 years, has used tinplated bussing or at the least tinplated lugs.

As Golddigger pointed out, tinplating has more advantages than disadvantages.

 

[topgone]

I would assume that it was silver plated unless told otherwise.

Silver plating is good for moving contact surfaces. For fixed bus bars, tin plating will do. A tin plating of 10 microns could be at par with a 1 micron silver plating, cost-wise, I was told.