Electrical – Why would you use copper electrical conduit

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This is not "home" improvement per se, but it fits the spirit of this stack exchange. While waiting for my train I was peeking into a ceiling that had all of its slats removed for some kind of installation. I noticed there was a lot of new electrical conduit being laid which was made of copper. This struck me as really odd because this stuff is usually laid as aluminum or some kind of steel; copper is really expensive, it's not rust proof, nor is it electrically or thermally insulating, so I'm not understanding the choice in a more expensive material. The only answer I can possibly come up with it's better for its environment (moisture, against concrete; something re: anodization)

Here's an extremely professional photograph of the aforementioned:

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Why would this be done?

Best Answer

I'm guessing it's plumbing, not conduit. Unless you actually see wires running through the tubing, I'm not convinced it's conduit. In the US only certain types of conduit are listed for use, and I'm sure they are similar in Canada. Copper is not among those listed, so it's not likely it would be approved by an inspector.

In a comment you mentioned that the pipe was connected using "nuts", and therefore could not be used for water. However, I disagree. A union is a fairly common fitting in plumbing. In fact, you'll probably find some if you look at the plumbing for the water heater in your house.

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Update:

After further searching National Electrical Code, I found this...

National Electrical Code 2014

Article 344 Rigid Metal Conduit: Type RMC

II. Installation

344.10 Uses Permitted.
(A) Atmospheric Conditions and Occupancies.
(2) Red Brass RMC. Red brass RMC shall be permitted to be installed for direct burial and swimming pool applications.

(B) Corrosive Environments.
(1) Galvanized Steel, Stainless Steel, and Red Brass RMC, Elbows, Couplings, and Fittings. Galvanized steel, stainless steel, and red brass RMC elbows, couplings, and fittings shall be permitted to be installed in concrete, in direct contact with the earth, or in areas subject to severe corrosive influences where protected by corrosion protection and judged suitable for the condition.

(C) Cinder Fill. Galvanized steel, stainless steel, and red brass RMC shall be permitted to be installed in or under cinder fill where subject to permanent moisture where protected on all sides by a layer of noncinder concrete not less than 50 mm (2 in.) thick; where the conduit is not less than 450 mm (18 in.) under the fill; or where protected by corrosion protection and judged suitable for the condition.

Which means it's possible the conduit is not copper, but red brass. According to wikipedia, red brass may be 85% copper, 5% tin, 5% lead, and 5% zinc.

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