SWA long 140M run please help!!

[FCC5206]

Evening all
I have been asked what size cable will be required for a long run. I know there are heaps of threads on here from people too lazy to do their homework but I have and am still lost so sorry if this has been covered i just cant find the answer.
The run is to power a stable block which the customer has told me needs power equivalent to a 2 bed house!!
The length of the run is 140 meters!
Taking into consideration max demand and diversity after doing my voltdrop calcs i come up with a 2 core 95mm2 to achieve the required 5% drop!! I know this is absurd and was wondering if anyone could point me in the right direction

Thanks

Chris

 

[trev]

You can take minimum cable size for fuse a short distance, connect it to upsized cable for the long run, then downsize it back for final connection to load. 140m is a long way; hope it's being trenched, and not ducted!!

Daft way of doing it imho mate. More calcs to do, at least with one cable you only have to do your VD once.

 

[telectrix]

from OP'spost of what the client seems to require regarding loading. i'd definitely go for a new supply.

 

[trev]

Completely agree Tel

 

[jeremy]

I'd rather do 2 calculations than try and terminate 95mm or 2x 50mm in an existing enclosure! but each to their own; we haven't seen what he's thinking of connecting to yet!

 

[Rockingit]

I'm in the new supply camp, too. If it's being put in to future-proof for a possible change of use then it's a no-brainer as far as I'm concerned. 140m of SWA at probably around £10/m, plus all the messing about and odds n sods, get's you quite far towards paying for a new supply.

 

[Engineer54]

Once you get the supply availability and stable requirment side sorted out, start thinking in terms of parallel SWA cables to take that supply to the distant stable block...

 

[Rockingit]

E54..... length/current on parallel runs I understand, but how do you calculate for VD?

 

[Engineer54]

E54..... length/current on parallel runs I understand, but how do you calculate for VD?

Just as a rule of thumb, If using two cables it's roughly Half the cables stated figures of one cable, and double the Current Carrying Capacity...

 

[Knobhead]

Parallel feeds makes sense to me. Less hassle to pull in and make off.

As for a new DNO feed to the block, I wonder what size cable the DNO would put in? I’d lay a safe bet it won’t be 95mm!

 

[tigerpaul]

I actually put a feed into a stable block years ago. The supply required was equal to a normal domestic property requirements.
Why so large? You may ask..
Because it was never intended to be used as a stable. They built it with the intention of converting to residential property after tue minimum 5 years had passed.

 

[i=p/u]

as i say tell them , what you suggest as an electrician, let them decide, you can only future proof if the pay for it, but at present 25m cable to run a few heaters

 

[Engineer54]

when you do get your definite max demand figures, don't forget that it could still be cheaper to run it with parallel supplies, ie 4 core SWA. Also the larger size doesn't need to go all the way from source to load. You can take minimum cable size for fuse a short distance, connect it to upsized cable for the long run, then downsize it back for final connection to load. 140m is a long way; hope it's being trenched, and not ducted!!

That is a totally idiotic suggestion, apart from anything else, how much do you think your going to save on cable costs then?? lol!!

 

[Engineer54]

I'd rather do 2 calculations than try and terminate 95mm or 2x 50mm in an existing enclosure! but each to their own; we haven't seen what he's thinking of connecting to yet!

Why would you expect to use 2 X 50mm cables for a supply requiring a 95mm cable?? Do you understand the principles of parallel cabling??

 

[captainkev]

suprised nobody mentioned solar panels, no digging or pulling big cables!!!

 

[Jonny66]

and no power with a huge bill:wink5: