long, long run.....

[FAA Greenie]

Hi Guys,

Quick one for you all. A client i am currently working for has asked me to quote him for supplying a wooden workshop he is planning on building in his (very large) garden. The problem is he plans on placing it 200 meters away. He only wants enough capacity to operate light stuff such as drills and a kettle etc so i have allowed for 2.5Kw (kettle plus a bit of extra). Obviously the limiting factor here is voltage drop and my calculations say i need a 10mm 3 core SWA which alone comes in at near enough £900. If he can come down to 150M i reckon 6mm or 4mm at 100M. Am i missing any tricks to get this price down? (I'm happy to export the earth etc, he is on a TNC-S system), but would it be any cheaper to use two core SWA and sink a good thick Earth rod in? He lives at the bottom of a valley and the ground is always nice and damp apparently. Any thoughts or similar installs?

 

[SMB]

Thanks IQ.

 

[FAA Greenie]

Thanks for your replies gents. Glad it didn't turn into a huge debate that this subject often does!! Yeah, i agree, pure economics is pointing to the TT but if he is happy to pay the extra i would rather keep a guaranteed, year round earth for the guy. He has no plans for any other services up there, ie water so the arrangements will be pretty easy to keep within the requirements for equipotential etc. Just be such a shame to run 10mm cable up there and put a 10A mcb on the end of it!!

 

[VoltzElectrical]

Yes but the adiabatic does not apply to TN-C-S earthing/bonding calculations.

I am not disagreeing with you, I would like to read it in full. Can you tell me where it says this please. I just read chapter 54 and couldn't really find it. I have a few more questions too, but in due course.

CXheers

 

[IQ Electrical]

I'm 'out and about' at the moment but I think 544.1.1 is the regulation, I'll check when I get back to the office.

It refers to table 54.8 'where PME conditions apply' and references the suppliers neutral conductor CSA.

Remember that on PME systems, the earthing conductor also serves as a main protective bonding conductor and must be sized accordingly.

 

[VoltzElectrical]

I read the table before i originally posted, and noted the 'where pme' conditions apply. having re-read it, i understand it that the bonding conductor to gas/ water etc.. in pme installations is sized according the the size of the neutral.

And where not pme, then it is sized in relation to the size of the earthing conductor.

 

[VoltzElectrical]

is that correct IQ?

 

[VoltzElectrical]

sorry to be a pain, fella,

could you confirm or deny my understanding on this please.

 

[needasparks]

That is painful when you have to shell out so much on cable, I had to run 25mm to run some electric gates but then his drive was 1/4 mile long.

 

[VoltzElectrical]

how much was THAT!??