This week's question is simple.

Is your/client(s) facilities interior wiring mostly copper of aluminium.

Copper
Aluminum
It depends/quite a mix
I don't get involved in this area

Outdoor/overhead equipment is almost exclusively aluminum or ACSR (aluminum coated/steel reinforced). Indoor equipment is almost exclusively copper. And then we get into silver or tin plating on bus bars, and of course arguments for/against aluminum vs. copper windings in transformers and I've worked with both.

And if this is leading up to the obvious...the scant documentation showing definite differences in the way that aluminum responds compared to copper in terms of incident energy, that doesn't even begin to touch on the fact that the enclosure itself or many lugs might be something other than copper and thus might have a difference response. This is akin to trying to answer questions about equipment configuration within an enclosure since it is known that mostly the equipment absorbs some of the radiant energy and reduces incident energy well below that predicted based on laboratory tests of effectively "open" equipment, with or without "barriers".

Outdoor overhead conductor is ACSR and often AA as well. For MV cable applications aluminum has an excellent history as long as the correct connectors are used.

Hi All!

Actually the question was a lot simpler than it appears. I probably should have prefaced it with some introductory information. It wasn't really about arc flash but more about - does anyone use aluminum wiring inside? Of course many older buildings still have it.

This is really based on the 1977 Beverly Hills Supper Club fire just south of Cincinnati, Ohio where the suspected cause was attributed to faulty aluminum wiring. I was a Sophomore in college at the time about 2 hours up the interstate but vaguely remember it. I know home inspections seem to flag aluminum wiring (older homes) as well.

Here is one of many links about the event: http://www.nytimes.com/1985/07/16/us/wiring-was-at-fault-in-supper-club-fire-jury-finds-in-retrial.html

As always, some good comments - always appreciated!

- Jim

I think you'd have a hard time finding #10 and 12 aluminum romex style that was used in the receptacle and lighting circuits where the problems occurred.
I dealt with a mobile home that had the stuff. Pretty good charring on the heavier loaded receptacles such as those used for vacuuming and hair drying.