Help, multiple circuits external supply 7 core SWA

[typical.me]

Hi guys, wonder if you could help,
I have been asked to supply power and lighting to a cabin/summerhouse 35 metres from house C.U.
Customer has already installed 7 core 2.5mm SWA underground (he says he "acquired it" from a friend at YEDL)
All calculations are fine for a load max of 2Kw (volt drop approx 5.9v)
My problem is, because it is 7core, the guy wants to include within it, a seperate lighting cct for tree illumination, controlled at the house end when the cabin is isolated.
Just like to know your thoughts regarding safe isolation at house end for anyone in the future working on either circuit, i.e. how you would supply both circuits.
1) from 2 seperate spare ways in c.u. suitably protected
2) create a distribution circuit, either 25mm tails & henley block or 6mm from c.u, to a 2 way "garage" cu and then feed from there within the swa (adaptor box if nescessary)
Also, sorry to be a pain, your thoughts on protection at cabin end.
System is TN-S
No extraneous conductive parts at cabin end
Sorry for long post
Thanx
Mick

 

[malcolmsanford]

Reg 521.7 Two or more circuits are allowed in the same cable provided requirements of section 528 is met. So that would mean other srvices and you are ok with that as far as I can see.

As your only working with a 2.5mm and that is quite a run for that size cable, if there were spare ways in the exising CU I would use them. Depending on what type of board it was I would go for RCBO's on a non protected side.

If you have just a split board with no non protected side then perhaps a new 2 way board would be better as you don't want the chance of nuicience tripping. Then RCBO.

I would terminate into an adapatable box first and use a little piece of din rail with klippons. Terminate all 7 cores that way.

TN-S then Earth OK. No bonding issues with no services in the Cabin. Again terminate into an adaptable box. As the socket will give you full isolation and function switching that will be ok. You may though think about fitting a double pole switch for the light if you having a switch in the Cabin.

 

[Tester Steve]

Check the voltage drop for the lighting circuit.

Steve.

 

[typical.me]

Check the voltage drop for the lighting circuit.

Steve.

Hi Steve, thanx for post,
was more concerned about safe isolation at house end, forgot to mention load on lighting.
No more than 1Kw tops absolute max!! Couple/ three 100watt halogens, couple of elv circuits, and room for expansion, so 1000/230= 4.35amps max
18mv/am x 4.35a x 35metres = 2.7% just within 3% limit.
What are yor thoughts on light switching control at house end?
Cheers
Mick

 

[Tester Steve]

Hi Steve, thanx for post,
was more concerned about safe isolation at house end, forgot to mention load on lighting.
No more than 1Kw tops absolute max!! Couple/ three 100watt halogens, couple of elv circuits, and room for expansion, so 1000/230= 4.35amps max
18mv/am x 4.35a x 35metres = 2.7% just within 3% limit.
What are yor thoughts on light switching control at house end?
Cheers
Mick

Cant see a problem as long as the switch can take the load.

Steve.

 

[Marvo]

Are you going to run a separate earth wire or are you going to use the armor of the cable as an earth?