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

Austrian designation for zip cord is YZWL (Zwillingsleitung).
US designations are SPT-1, SPT-2 and SPT-3. I think SPT-1 equals our YZWL, SPT-2 is already much heavier but still only one layer of insulation, SPT-3 is AFAIK only used for air conditioner cords. I think SPT-1 is still pretty common for cheap appliance cords. Extension cords are usually SPT-2. I have some old US zip cords, and the sheathing seems to be way tougher than our YZWL. Probably different plastic.

Zip cords used to be common on small appliances here up until the 1960s/early 1970s. I have plenty of old radios, phonographs, lamps etc. as well as some test equipment which uses it.

There was also a 3-wire version used occasionally where a ground was required.

In the U.K., the 2-wire zip cord is also sometimes called "Figure 8", for the shape you see if looking directly at the cut end of the cord.

Time to revive this thread.

I think I'll switch to Russian AVVG, an 660V outdoor cable, which has an outer sheat. You don't want the thing to fail and have to dig it up...

The voltage drop keeps bugging me. I talked to a Swedish engineer working in Tanzania. He figured on a 25% voltage drop. (sic!) "The light bulbs give off a rather reddish light"

If I go for 10%, I would still extend the the maximum distance for a 2.5A service on 2.5 mm2 Al to 400 metres.

Here's my latest idea: Use two wire 460V to the house. If the consumer only needs lighting, two 230V bulbs in series could be used.

If he/she wants to use appliances too, 460-230V autotransformers will be sold by the utility. Reasoning: Someone who has the money for appliances will also have money for a transformer.

The transformer would be similar in appearance and size to the British 230-110V construction site transformers, which seem fairly rugged and inexpensive. This approach offers an inexpensive 1 kW service for distances up to 800 m. Of course, a larger conductor will increase capacity or extend the range. E.g. 6 mm2 extends the range to 2 km.

paul:

2 wire clearish yellow twisted pair was quite common on old lights etc here in Ireland.

What was that?

C-H,
Power cables generally have 2 ratings.
The first is the voltage between cores.
The second is the voltage between the conducting cores to earth.
Over here, the cables have a 600V/1000V rating, respectively.
This is for LV reticulation within a Domestic installation, with 2C+E or 3C wiring.
Using this sort of wire in a Distribution system would be frowned upon!.
Use Neutral-Screened or Armoured for Direct Burial.
All stuff we use for Distribution is 1000V/1000V or if you want to be really silly, 33kV/33kV Alu.
Also, all of our U/G stuff is run in 150mm (6") Orange Conduit, regardless of the size of the inside wires, up to a maximum size of conduit of 400mm diameter, for really large feeders.

Mike,


Yes. Just like the Austalian/NZ cables, European cables are rated 300/500V, 450/750V or 600/1000V. Flexes are 300/500 or 300/300. These ratings are not universal: Americans have their own and apparently the Russian do too. This really is rated 660V, which I take to mean 380/660V.


Huh? That's not the case in other places.

It is of course preferable to use armoured/ neutral screened as it's safer and makes it more difficult to tamper with the cable. This has to be weighed against the increased cost.

You can use conduit, but it is a practical consideration, not a safety consideration unless the manufacturer states that the cable needs to be protected from mechanical damage. Some cables have to be in conduit, others don't.

C-H

I really don't see the point in giving people a limit of only 25 watts per house where all you can use is a refrigerator bulb in one room.

I'd say give each house a 10 or 15 amp supply - that should be enough for say....1,200 to 1,800 watts (if my math is correct by using 120 volts).

That should be enough for one 60-watt lightbulb in each room (assume one main family room, one kitchen area and a sleeping room or two plus a bathroom), plus the odd electric fan, transistor-radio or small TV and eventually as the economic situation improves...a small electric refrigerator.

Sven,

calculate the wire size needed for your 15A supply to keep the voltage drop to a reasonable level. Then calculate the price of this cable. Then look up the income level in developing countries.

But, yes, at only 25W a photovoltaic system is a cheaper option.

If regular 230V light fittings are used, would it be such a good idea to do this, bearing in mind that when a bulb is removed the holder will have 460V between its terminals?

In fact, would it be a good idea to introduce such high voltages at all in homes in a developing country, even if it is still only 230V to ground?

Sort of like a translucent browny-yellow insulation, through which you could see the conductors?

Twisted pair of that type was fairly common on table lamps and such like here in the 1940s/early 1950s.