How far is too far - extension to accommodation unit

[Grian]

When my house was built I was connected to an existing transformer approximately 80m to my north. I feel they mentioned this was as far as they would lay cable before requiring a new transformer - I remember being hugely relieved they didn't! I always planned to have a holiday accommodation 'hut' in the garden and to this end the electrician connected about 40m of heavy duty cable to the house, ready for when it was built. I've found a much better spot for the hut, but it is another 80m beyond the house, and wonder if it is going to be possible to extend electricity that far? I think there is capacity in the transformer for this.

 

This is the diagram from my connection quote showing what is in place.

 

 

In case it is relevant, the hut is for 2 occupants, it would have a normal cooker (ceramic not induction), a shower, a panel heater... 

 

A new transformer would be prohibitive so the alternative would be to go off-grid, but it is in a sheltered spot shaded from the south so solar would be difficult - unless I could run a very long cable from the adjacent hillside.

 

My poor effort at photoshopping the hut onto the site below. Thank you in advance and apologies if I have left out key info, I suspect if it isn't included then I don't know it.

 

Edited February 3 by Grian
new info

[joth]

So first, so long as the standing voltage at your property is acceptable even when you're drawing max load, then the length of cable running into your house has little bearing on the length you can run from your house onto an outbuilding.

 

The power loss (voltage drop) along a long cable run is proportional to the current being drawn. Using large diameter cable will reduce the effect. There's  voltage drop calculators that can give a ballpark idea. This one says 10mm2 swa will have 8V drop when delivering 6kW over 80m, which should be fine.

 

If there's still issues, if you can shift the high power loads off of electric to bottled gas then the remaining loads (lighting and a phone charger) will be no problem at all.

 

Edited February 3 by joth

[Adrian Walker]

You will get a small voltage drop, but nothing to be worried about.  Max load for both is/might be more of an issue.

[Grian]

Brilliant! Thank you so much for this advice.

 

Roads dept have said today that they aren't concerned about the new entrance so that is two massive steps forward. I don't care if it is Monday, this calls for half a cider!