armoured cable to log cabin

[willardx]

Hi all,
I am thinking about a cabin at the end of the garden. Its a long garden! I'll be lookin at about 100m of armoured cable. I already have a 30 amp spur point on the outside of the house ready to go. Any ideas about cost for cable and the sparky to wire it in, and whether its ok to run cable down hedge or trenching requirements? Any info gladly received. Ta.

 

[flameport]

As a quick estimate, 2 core 25mm² SWA minimum, 100m of which will cost £500+ and will arrive on a spool too heavy for one person to move on their own.
Slung in a hedge is not acceptable, so you will need 100m of trench digging out, which could easily cost as much as the cable to put in it.

What exactly is a '30 amp spur point', and what items will be used in this cabin?
If not already built, locate the cabin much nearer to the house.

 

[willardx]

Thanks for the reply.
30 amp spur point ! its what an amateur calls the thing i got the sparky to put on the back wall of the house when we had to do a full rewire. It was originally for a planned sauna down the end of the garden, and has its own bit on the consumer unit etc. The sparky said its 30 amp which i guess was the power to run a sauna.
I don't really want to locate the cabin closer.
The cabin' s power draw will be a pc, possibly very small fridge, lights, and possibly a very small oil fired radiated (500w) so not loads.
I can dig a trench myself so that's no problem.
The 100m is along fence lines so a direct trench should take it down to 80m.
So im thinking :
Does the cable need to be 25mm?
Any idea on price to wire up if i do trench and the consumer modifications are already done?
Any other considerations?

 

[Jackrae]

Using TLC calculator and a 2kW load estimate, 4mm^2 seems adequate
https://www.tlc-direct.co.uk/Techni...30&length=100&submit=Calculate+Min+Cable+Size

 

[Taylortwocities]

I would not go smaller than 10mm² cable. Given that length, and to future proof it.

 

[oldbutnotdead]

As above- digging 100m of trench is not a trivial undertaking, the cost of the cable will become a bit insignificant. While you've got the trench open, sling a couple of runs of ducting in as well (for data, CCTV, alarm, anything else that might come along).

PS I bought the SWA for my garage from this lot https://www.electriccable.co.uk- best price I could find (for your job you'd get an ever better deal, £4.36/m net)

 

[ericmark]

I looked at 6mm² as an example using a 16A MCB for supply which seems reasonable and the maximum length to maintain the 6.9 volt drop for lighting is 66 meters. Drop to 13A then 88 meters, at 10A we hit the 107.5 meters.

It would seem as if 6mm² would likely fit the bill but one has to understand the limitations. Although the regulations say 6.9 volt drop is maximum for lighting non dimmable LED lights can often run from 85 to 265 volt so one can get around the volt drop problem for lights, the 11.5 volt drop for sockets and like will allow a 16A supply. At 20A drops to 86 meters.

So even with a 20A MCB I personally would not worry about volt drop using 6mm² as long as no wire wound ballast fluorescent lamp is used. I would say LED lighting is the way to go. I have noticed at home my volts have always been around the 245 volt mark, but now have dropped to 230 volts some times even lower, I will guess some one with solar panels has complained about the high voltage. I point this out as although today all may work next year the volts may drop.

Big point is if the electrician will sign off the work. So really this is not the place to ask the question, ask your electrician.

 

[Iggifer]

PS I bought the SWA for my garage from this lot https://www.electriccable.co.uk- best price I could find (for your job you'd get an ever better deal, £4.36/m net)

That price would be correct if he wanted 3 core SWA, which he most definitely does not over that distance. 2-core is only £3.38/m+VAT

 

[flameport]

Does the cable need to be 25mm?
Any idea on price to wire up if i do trench and the consumer modifications are already done?
Any other considerations?

Cable can be smaller if you don't want a 30A load at the end of it.
Price depends on many things, but in any event you must get someone involved from the start - installing cables and then asking someone to just connect the ends will not usually get the result you wanted.

 

[ban-all-sheds]

I am thinking about a cabin at the end of the garden.

Bear in mind that even if in all respects it's a Schedule 2 Class 6 exempt building it is not exempt from Part P, or the notification requirements for electrical work, so if you don't use a registered electrician you will need to apply for Building Regulations approval before you start.

 

[ban-all-sheds]

While you've got the trench open, sling a couple of runs of ducting in as well (for data, CCTV, alarm, anything else that might come along).

100+m is a bit of a step for your average wifi link.

 

[Adam_151]

Its also borderline for the stated maximum for ethernet IIRC? (Though I expect that if the OP used good quality cable then the connection would be usable, but maybe not able to connect at the faster speeds)

It would get expensive if one had to start going down the fibre route!

 

[ban-all-sheds]

6A will do 10Gb over 100m. So should be OK for a bit more at 1Gb.

And there are lots of extenders available.

 

[willardx]

Cheers all, some really handy bits and pieces there.
I obv need to speak to the sparky but always good to have a bit of a clue before hand. I was gonna sort web connection with one of those powerline extender things. Hopefully it will be ok. Thanks again. 10mm 2 core seems the overall best call on cable.

 

[Iggifer]

Think you'll struggle with powerline over that distance. Also think you'd struggle to find anyone here who would approve of poweline adapters.