Bus Bars: AL vs. CU

Status
Not open for further replies.
C

cvirgil467

Senior Member
Location
NewYork
This topic has probally been beaten to death already, but here goes:

Anyone know the pros and cons of using aluminum bus bar in switchboards, panelboards and transformers? My initial reaction was no way. But i cannot find a good reason not to.

Any links to articles would be helpful

Thanks.
C
 
While everyone loves copper, aluminum is less costly.
I have worked around switchgear and bus-duct for the last 30 years.
I have never seen a reason not to use aluminum buss.

I can't remember a time when I have seen an aluminum buss fail.
Maybe it's my alzheimer's though. :D
 
I would GUESS that they both pass the same UL testing and standards. Copper is probably the better product, but if I'm paying the bill, aluminum is just fine.
 
I suppose there are horses for courses. I came across this forum when I was looking for figures for aluminium busbar ratings.
This because I was bidding for a project that requires Al bars to be used.
It's an upgrade to add to an existing rectifier system which currently uses Al bars. In the event, I went to site and physically measured the existing (live) bars - with a plastic ruler I might add....and lived to tell the tale.
One of the constraints is that there is a 100ft span with no intermediate supports and Ali conductors for the same current are about half the weight of copper.
That's one of the main reasons why it is commonly used for overhead transmission lines.

That said, I can't think of any panel board or motor control center where we have used aluminum. Maybe just because customers prefer copper?

I have been told recently that Cuponal is the way to go.
It was probably by a sales rep who was obviously being absolutely objective....
 
30+ years in the business, The MCC and switchboards and I-Line panelboards have been probably 75% aluminum. Just about the only time I have used copper for these has been on government projects (taxpayer money).
 
Aluminum is actually a better conductor than copper. The bad rep that aluminum carries came from all of the AL wiring used in residences where subsequent work was done without regard to dissimilar metals issues. Also, wires tended to evpand and contract at different rates than the terminal devices, so any sloppiness on the part of the installer would tend to make things worse.

For bus bars though, these issues just don't hold water.
 
Jraef said:
Aluminum is actually a better conductor than copper.
Click to expand...
Not sure where you got that from nor in what context you intended it....
Electrical conductivity of copper is about 1.5 times that of aluminium and thermal conductivity about double.
On both those counts, copper would be considered to be the better conductor.
 
jim dungar said:
30+ years in the business, The MCC and switchboards and I-Line panelboards have been probably 75% aluminum. Just about the only time I have used copper for these has been on government projects (taxpayer money).
Click to expand...
Interesting, that. It just seems not to common practice, at least in UK.
The only place I have seen aluminium bar used is for projects like the rectifiers I mentioned above. These are usually pretty high current with long runs to the load so there are significant financial savings to be made by using aluminium.
 
Sorry, I was thinking of wire conductors and that aluminum is used because it has a lower resistive density, meaning it can carry more current per pound than copper. That makes it a better conductor for overhead cables, but would be relatively irrelevant in bus bar applications.
 
Jraef said:
Aluminum is actually a better conductor than copper. The bad rep that aluminum carries came from all of the AL wiring used in residences where subsequent work was done without regard to dissimilar metals issues. Also, wires tended to evpand and contract at different rates than the terminal devices, so any sloppiness on the part of the installer would tend to make things worse.

For bus bars though, these issues just don't hold water.
Click to expand...

Actually the bolted connections are more difficult to design to allow for the greater physical expansion than copper. The stab-on connectors for MCC's are also more difficult to design and present greater potential for thermal failure. Copper oxide forms a protective layer that prevents further deterioration.
Investigating aluminum wires as a suitable alternative for general wiring applications AND taking voltage drop into consideration for long runs, it remains a less than clear-cut decision.

Aluminum pricing is doubled in the past 5 years and was up at 300% at some times during that period. Copper is trending down lately and now it is about double as 5 years ago, so the ratio is same as with aluminum. The max. was at 400%.
 
Status
Not open for further replies.
Top