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#139350 - 11/02/03 09:45 AM Cheapest possible cable?
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
I keep on with my little project concerning very low cost power distribution.

I think some simple overhead cable is the best distribution to each house. Bare wires seem rather unsafe and are exposed to theft of electricity.

The cheapeast type of cable I can think if would be something similar to an American zip-cord with alumin(i)um conductors. Has anyone seen something like #14 or 2.5 mm2 Al for outdoor use? I can't find anything on the net.

(Someone is likely to bring up the possible fire hazard: I think that can be avoided by using stranded wires, suitable terminations and a trained workforce. The wiring inside the house will still have to be Cu, of course.)

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#139351 - 11/03/03 05:10 PM Re: Cheapest possible cable?
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Can't help you with the specific cable type, but just wanted to let you know that many houses here in the US are served by overhead Al wiring to the meter, where it is then changed over to Cu.

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#139352 - 11/04/03 03:34 AM Re: Cheapest possible cable?
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
I don't recall ever seeing an aluminum version of the sort of cable you're talking about.

Why only #14 / 2.5 mm? Are you thinking about a service limited to 15A or so?

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#139353 - 11/04/03 04:39 AM Re: Cheapest possible cable?
David UK Offline
Member

Registered: 10/03/02
Posts: 134
Loc: Inverness, Scotland
Would Al cable of such a small c.s.a. not be mechanically weak, and prone to break very easily in an o/h line situation.
In the UK the minimum size permitted for Al conductors is 16mm.

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#139354 - 11/04/03 06:21 AM Re: Cheapest possible cable?
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
ThinkGood,

that was what gave me the idea. If it's used in America, it's probably the cheapest way of doing things. (Don't get me wrong: Americans are good at finding cheap solutions)

Paul,

 Quote:

Why only #14 / 2.5 mm? Are you thinking about a service limited to 15A or so?


More like 1A and 2.5A services. Of course, you'd market them as 200W and 500W services. Sounds better.

David UK,

am afraid it might. But a copper conductor would be even thinner.

How do phone wires work?

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#139355 - 11/04/03 10:19 AM Re: Cheapest possible cable?
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Ah.... You're linking this up with those current-limiting devices from another thread, right?

Just as a matter of interest, does anyone have any idea what the cost differential would be between Cu and Al for cables this small? Would it be high enough to make the use of aluminum worthwhile?

By the way, phone lines are generally tinned copper, around #22 or #24, or metric equivalents.

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#139356 - 11/04/03 10:29 AM Re: Cheapest possible cable?
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
...current-limiting devices....

Yup. I just read about 20W services somewhere in south east Asia. Yes, twenty watts! Enough to run one short flourescent tube.

The difference in cost between copper and aluminium is probably small and with copper I could go one size smaller. However I wonder what happens to it mechanically when the wind gets hold of the cable. A steel cable would be great from a mechanical perspective, but it's that voltage drop thing... I suppose I have to suspend the cable with a steel wire.

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#139357 - 11/04/03 10:39 AM Re: Cheapest possible cable?
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
I managed to find some Russian type building cable, APPV:

2*2,5 Aluminium € 70/kilometre ex works Lithuania.


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#139358 - 11/04/03 12:57 PM Re: Cheapest possible cable?
Texas_Ranger Offline
Member

Registered: 12/17/01
Posts: 2343
Loc: Vienna, Austria
Hey, that's what our NYIF looks like, only it's light grey! And of course copper.
Wouldn't the voltage drop be a problem anyway with such thin wires? How long do you plan on making those runs?
Steel wire definitely isn't a good idea. I read somewhere about a trolley bus service in Vienna (1940ies), they fed 750V into the wire and on the other end they had about 300... with only 1 bus... the service never opened to the public.

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#139359 - 11/04/03 01:22 PM Re: Cheapest possible cable?
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
NYIF ? I'll have to look that one up.

Voltage drop is a nasty thing. Pretty soon you end up with a huge cable.

Let's say I want to make a 150 m run from the transformer and have a 2.5A service. I admit that's not entirely realistic, but it's a starting point. What would the voltage drop be?

Vdrop = 2 x length x amps x resistivity / CSA = 2 x 150 x 2.5 x 0.03/2.5 = 9 V

Acceptable, but I think the lights will dim a bit when you turn on the TV...

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