ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Cheapest possible cable?

20 watts?! Just about enough to run my miniature soldering iron, so long as I didn't have the fluorescent magnifier lamp on at the same time!

wa2ise said:
What would be the point of having them anyway, it would take months to clock up a kW of usage at 20W.

When nuclear power started here in the 1950s there was talk that one day it would be so cheap that we could dispense with meters.

I don't think this is quite what they had in mind!

Paul and Trumpy,

I too thought a 20W could never lead to any serious power consumption. But then I calculated it: Assuming ten hours of use per day, you will have used up a kilowatthour in five days. Sure, that still isn't much, but in a year it amounts to about 70 kWh.

Trumpy,

a 230/460V system seems to be the cheapest option. I don't think I need any overcurrent protection apart from the service limiter. I suppose you could put a limit in the reset function: If it trips three times within a certain period of time, it stays tripped until manually reset.

wa2ise,

the setup you descripe is not uncommon, although a diesel would be a more common power source than a hydroelectric dam. It works if sized by the locals. Foreign engineers and electricians (brought in by aid agencies) tend to oversize the systems.


[This message has been edited by C-H (edited 11-17-2003).]

C-H,
Sorry,
I didn't xplain my last comment well enough.
What I meant was Short-Circuit protection, in case there is an insulation breakdown, somewhere in the system and the phase contacts the neutral conductor.
Will the service limiter, provide this function?.
Also with using 230/400V LV supply, you need to have wiring that is insulated to full working voltage, is Zip-cord rated that high (in voltage terms)?.
[Message edited to add last bit]

[This message has been edited by Trumpy (edited 11-17-2003).]

C-H mentioned 230/460V above. I think he is envisaging a 3-wire single-phase system rather than 3-phase.

Yes it is. I've used it for several cheapskate wiring projects that were supposed to look old (Basically a long piece of zip cord with a round ungrounded plug and an old brass light socket). Here in Austria they now print "42V max" on it, but I think there are several countries that still list zip cord for 220V.
Many old radios still have zip cord, as it is usually in pristine condition no one bothers to replace it.

Trumpy,

regarding the protection of the cables: As I understand it, it will respond to short circuits as well. It's likely it can only handle a fairly limited current. A circuit breaker or fuse after the transformer could be used to catch really bad faults.

On the cable thing: If I take Trumpy's advice on burying the cable, zip-cord might no longer be a very good (safe) choice. I know there is a cable called UF in the US which is used as underground cable. Maybe something like that, but with only one insulated conductor and one bare conductor for neutral/earth? If you need both legs (460V), you'd use two insulated conductors. Input from those familiar with this type of cable is welcome!

[This message has been edited by C-H (edited 11-19-2003).]

What is zip cord? Is that the "Loudspeaker cable" with only one one coating?

Zip cord is like loudspeaker cable but, particularly in the USA, was available in a heavier version that was commonly used to carry 110V AC to light appliences.
As far as I know is still in common use in the USA for lamps etc.

In Europe double-insulated cord has been standard for some time, however some old appliences may still have zip cord (or even twisted-pair), particularly old lamps and radios.

An American Zip cord extension lead: