Help in re-wiring a long 350m outdoor run

[bobfleming70]

We need to rewire a long outdoor run from a house to a workshop approx 230m away through many trees, and to a further shed another 120m on from that (total run 350m).

In the house is a fairly modern fusebox/circuit breaker. The previous owner simply laid down non-armoured normal 3-core internal mains cable (because it was cheap, probably) along the ground from the house to the workshop, then from there on to the second.

That was some years ago, but badgers have gnawed it over the years and now has at least 5 joints along it, most under buckets. When it rains, or power tools are turned on for example, the breaker in the house repeatedly trips. If we're in the workshop we have to trudge up to the house every time to reset it. It's driving us mad.

We're looking at replacing it with a single run of proper SWA cable. Is 3-core 1.5mm OK or should it be thicker because of the voltage drop? Any thing else we should be doing (like extra RCDs in the workshop/shed?)

All advice gratefully received,
many thanks

 

[IJWS15]

For this I really would call an electrician.

 

[riveralt]

Try working it out here

http://www.tlc-direct.co.uk/Technic...30&length=350&submit=Calculate+Min+Cable+Size

for 350m with a 3kw rating clipped direct that would be a minimum of 16mm2 SWA 3 core XLPE.

 

[holmslaw]

..

 

[sparkwright]

Probably cheaper to move the workshop.

 

[sparkybird]

 

[aptsys]

Probably cheaper to move the workshop.

Or possibly even get a new connection from the DNO

 

[ban-all-sheds]

for 350m with a 3kw rating clipped direct that would be a minimum of 16mm2 SWA 3 core XLPE.

For a 3kw load (13Amps) you need something like 3c16mm SWA.

You think so?

With VD at 2.8mV/A/m, and (presumably) lighting in the workshop?

Try 35mm² - be able to go up to 16A with that.

Edit - great minds think alike

No, they don't.

 

[ban-all-sheds]

Try working it out here

http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

Bob - when you do, make sure you select lighting circuit, if you have lighting, and do not select 3-core cable or it will do 3-phase calculations, and give you incorrect answers.

 

[bernardgreen]

Would the regs allow the use of a step up transformer to send power over the 350 metre at say 460 volts to reduce the current by half and then step down at the far end ?.

I think the answer is no but if you don't ask then you don't get.

 

[ban-all-sheds]

You can go up to 1000V before you leave the realm of LV....

 

[martinxxxxxx]

Shoot the badgers

 

[securespark]

You wanna dig a 350m trench???

 

[holmslaw]

..

 

[Lectrician]

Lets see your calcs then Holms....