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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: Mercury/Sodium Filled Speaker Wire
Message-ID: <2022@kitty.UUCP>
Date: Sun, 20-Sep-87 22:07:58 EDT
Article-I.D.: kitty.2022
Posted: Sun Sep 20 22:07:58 1987
Date-Received: Mon, 21-Sep-87 03:57:54 EDT
References: <3816@watdcsu.waterloo.edu> <3939@cit-vax.Caltech.Edu> <7578@felix.UUCP>
Distribution: rec
Organization: Recognition Research Corp., Clarence, NY
Lines: 54
Summary: Sodium as an electrical power conductor...

In article <7578@felix.UUCP>, dennisg@felix.UUCP (Dennis Griesser) writes:
> In response to mercury-filled speaker cables, Larry Lippman <1997@kitty.UUCP>
> warned about the toxic hazard presented by mercury.  Then he said...
> 
> >	Now, for a more practicable idea, consider the use of SODIUM-filled
> >cables, which have been available to the electric power industry for a number
> >of years.  Sizes go up to at least 500,000 circular mils, and I know for a
> >fact that the cable is available with an insulation rating of 15 kV for
> >direct-burial applications.
> 
> Sodium-filled cable really does exist.  Many years ago, my father worked in
> Union Carbide's NaCon division where they were being developed.
> 
> What Larry failed to mention, and should have since he was reminding us about
> the dangers of mercury, is that sodium reacts vigorously with water.  The
> insulation needs to be quite water-tight, and terminating the ends must be
> interesting.

	I was being facetious, so I didn't mention it!

	Sodium has approximately 40 percent of the conductivity of copper,
so it's not that bad a conductor.  Sodium has about 1/3 the density of
aluminum and about 1/10 the density of copper.  Sodium-filled cable is
extremely lightweight when compared to that of copper or even aluminum.
	Sodium is a byproduct of chlorine production, is quite plentiful,
and costs less per pound than aluminum.
	The use of sodium for underground high-voltage cables (4,160 volts
and above) awaited the development of a practicable cable manufacturing
process, and of a practicable and safe connection method.
	Sodium-filled cables for underground high-voltage distribution have
been used for at least 20 years.  The cable terminations have a "corkscrew"
which digs into the sodium filling inside the cable; this termination has
a plastic sheath which fits over the end of the cable and seals it with a
cement.  A conventional terminal lug protrudes from the cable termination
for connection to distribution apparatus.
	Besides being of low cost and light weight, sodium-filled cables
have the advantages of fault limitation and easy fault localization.
Unlike conventional cables which might have a fault (say, an insulation
defect or injury) with slowly increasing leakage to ground, the slightest
leakage in a sodium-filled cable causes rapid destruction of only a small
portion of the cable.  Following such a fault, the formation of sodium
hydroxide at the exposed ends of the cable seals the remainder of the
cable from moisture penetration beyond a few feet.
	Speaking as both an EE and chemist, I feel that sodium-filled
cable is an effective means of providing low-cost underground electric
power transmission for voltages between 4.16 and 34.5 kV.  However,
sodium-filled cable has been severely under-utilized.  I don't know why
this is, other than there appears to be some unfounded apprehension about
its use.

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
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