ECN Forum Forums General Topics of the Trade General Discussion Area Sodium cables

One of the oddest electrical technologies of the past is the sodium cable. As the name indicates, it's an insulated power cable with metallic sodium as a conductor, in place of the usual copper or aluminum. Apparently it was "the next big thing" for a while in the 1960s, but as far as I know, it never caught on - though it probably "caught fire" a few times!

On pages 24-26 of this presentation, there's information about sodium cables and a cutaway photo of
one:
http://www.ewh.ieee.org/soc/pes/icc/subcommittees/subcom_e/E4/2005/8Hans.pdf

The entire presentation is quite interesting; check out the "Blues Brothers" on page 19.

Alber

Interesting stuff!

How would you make a reliable electrical connection to a sodium conductor? Sodium is so soft that it makes the "cold flow" problems of aluminum look like nothing. I can't see how any kind of crimp or mechanical lug is going to stay tight.

Then there's the whole "reacts explosively with water" thing...

Yes, terminations must have been a major problem. The only thing I've seen in that regard is a reference to threaded connectors; I suppose they used some kind of lug that was screwed onto the exposed conductor. But it must have been difficult to come up with a design that could be screwed on tightly enough to make a good connection while not breaking the conductor.

It's really incredible that such a technology could actually have been approved and deployed by utilities. Apparently its only advantage was cost savings; surprisingly (to me) sodium was cheaper than copper and aluminum.

When I first heard of sodium cables, I thought they would be used for some exotic super-duper extra-high-voltage cryogenic superconducting transmission system, but in fact the application was ordinary secondary-voltage underground residential distribution.

When I brought up the topic on another list, a former lineman said one of the problems was that when water got into the cable due to jacket damage, the conductor would corrode for a long distance from the point of entry. His crew ended up replacing a lot of the stuff.