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350 meters extension cord

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SimonTHK

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Hello all you smart people :)

So I have 350 meters of distance that I want to provide with 230 volt and probably not more than 1 amp usage. Atleast 1 amp can be enough. I am just gonna use a regular extension cord for this.
Can anyone tell me if there should be any problems with this?
Also If I suddenly was to use the maximum power of 2200watt?
 

kubeek

Well-Known Member
Most Helpful Member
Also the impedance of the loop has to be low enough so that the breaker will be sure to trip in case of a short circuit, which is usually 5x the nominal current (for B type breaker, not sure the same class is used everywhere)
 

ronsimpson

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You probably don't know what wire size. Just a guess; 1 amp will be fine. 2200 watts is 10 amp. If the load is a motor it might not start and it will not run strong.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Hello all you smart people :)

So I have 350 meters of distance that I want to provide with 230 volt and probably not more than 1 amp usage. Atleast 1 amp can be enough. I am just gonna use a regular extension cord for this.
Can anyone tell me if there should be any problems with this?
Also If I suddenly was to use the maximum power of 2200watt?
350m is a hell of a distance - if you're only using 1A you should be OK with normal extension cable - but if you're using 2200W (and it's 3000W maximum in the UK) you're going to need substantially thicker cable, and preferably armoured cable (as it's obviously outside).

I've just checked 1.5mm mains cable, it's resistance is 13.3 ohms per kilometre, so your 700m is 9.3 ohms. Draw 10A through it, and you're dropping 90V !!!!.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
For a little story, way back in the 70's I used to do the PA for a local band, and one of the first gigs we did was for a summer fayre, in a field next to a primary school (my old primary school funnily enough). Anyway, we weren't allowed access to the school, so someone hired a generator to power the band and the beer tent.

All went well until it ran out of petrol, no one had thought to bring any, there was no where local to buy it, and we had all been accessing the beer tent to much to drive (I was walking the couple of miles home) :D

So we broke in the school, and ran a series of extension leads to the field, and connected the band gear and the beer tent to this lead(it was a LOT less than 350m) - all worked 'OK' except as the band played the lights in the beer tent went up and down, a LOT!!! :D

Still nice light show!.
 

Beau Schwabe

Active Member
Suppose you have a 2200 Watt Heater at the end of your 350 meter run.... even with 12 Gauge wire your losing 300 Watts within the wire due to IR drop, so the effective output of your heater would only be 1900 Watts and your wire will run a little warm at just under 1 Watt per meter.

14 Gauge even worse ... more than 450 Watt loss
16 Gauge ... 650 Watt loss

Reference:
http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.html
 

dr pepper

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Most Helpful Member
You'd calculate the impedances & trip times, and compare them with the guidelines or regulations in your country.
 

Beau Schwabe

Active Member
kubeek,

Unless specifically stated, the cross sectional area between solid vs stranded wire will be different.
It doesn't hurt as a good rule of thumb to add a little overhead anyway.
 

gophert

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Most Helpful Member
Let's say you want less than 10% voltage drop for your 700m distance (23 volts) at 10 amps.

That means you need 2.3 ohms or less resistance in your length of wire (700 m total) or 0.00328 ohms per meter.

Looking up ampacity charts, 10-gauge wire is 3.2 ohms per meter.

Use 8-awg wire if you want your 230 v not to drop below the 6% loss specification in the U.K.

Good luck.
 

hyedenny

Active Member
I have 350 meters of distance that I want to provide with 230 volt and probably not more than 1 amp usage.
That's almost a quarter of a mile of extension cords! Rather than spending all that money on extension cords, and still dealing with the significant voltage drop, it would be cheaper to rent a small generator, or maybe even a few batteries and an inverter depending on the time you need to run it.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
To summarise the facts from the other answers:

As Gophers says, you need less than 2.3 Ohms total cable resistance (round trip) to be able to run your 2200 Watt load.

The smallest standard cable that can achieve that at 350m length is 6mm ^2
You _cannot_ buy normal 230V extension cables with that large a cable size; the biggest ones generally use 2.5mm cable, which is far too small for that total length.


This is the size of cable you need; anything smaller will just not work.

You have a choice of rigid armoured:
https://www.superlecdirect.com/p-xl...MIsIPH27W94QIVbpPtCh08pg4PEAQYASABEgJm4PD_BwE

Or flexible armoured:
https://quickbit.co.uk/6mm-3-core-s...MItsvhoLa94QIVipXtCh3LtQtkEAQYAyABEgLL6_D_BwE

No other type is safe to use laid loose over that distance. It should still be supplied via an earth leakage circuit breaker at the source.

If it's going to be left in place, use the first type - SWA. Strictly speaking for a permanent installation it should be buried 18" deep or attached above ground along a fence etc., not just left on the surface.

If you want to be able to coil it up and move it, use the second type - SY.
 

gophert

Well-Known Member
Most Helpful Member
6mm SY is not all that big, 10mm overall diameter.
Still, that is 220+ loops of 1-meter diameter = 700m. I'm guessing that will make a meter tall pile.

Also, it will weigh about 240kg.
 
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