Just checking installation,

[new2this]

Hi all,
Right i just need my workings checked before i do anythng.
I have a shed that needs power. Its roughly 10m away.
Im using a 40 A MCB in the house CU and running 6mm SWA from there to a second CU in shed which will be using a 40A30ma RCD as its isolater.
The CU will have a 32a ring for the sockets and a 6a for the shed lights and garden lights.
Does this sound ok to everyone?
Also for outside lights which will be deck lights and 2 wall lights, will normal 1mm flex be ok, or shall i use SWA.
Thanks for your help, and before you say, get a professional in, I have sat exams for being an electrician, but as im sure you will agree sitting exams and actually getting experience are 2 different things.
Thanks again for any help you provide.

 

[alland1979]

for the decking lights I would use ARCTIC cable mate, its for outside use. instead of a 32a ring why not run a 4mm radial or a 2.5mm radial fed by a 20 mcb.

 

[ajelec10]

Radials all day long!!!
Dont like the rcd as main isolater although it is only doing the garage circuits

 

[kung]

In my garage ive just used a 20A mcb on non rcd side as not a final circuit so no rcd needed as submain/dist circuit so took off rcd side sats fault discrim ! and fitted a garage 63A rcd CU with 6A for lights and replaced 32A for 16A mcb for power ring or radial your choice id wire in radial but if ring if your on assessment from NIC they like to see r1/r2/rn testing as well as R1/R2 ect ! only joking ! Also what earthing system is it ? if PME/TNCS exported earth is ok for some applications if not spike it to convert to tt and make sure no cpc/earth is mixed so if using braid off swa you need to isolate it to advoid this happening !. Very important if any metal struc etc is in contact with earth ! I always TT outside buildings anyway that way your covered then just loop test and away you go job done esp as the DNO want to convert all earthing systems to PME/TNCS ! so does this mean we can prosicute if someone gets killed using PME/TNCS when they drop a neutral ? involuntary manslaughter mabe ?
Regards
Kung.

Anyone elses thoughts ?

 

[flukey]

its ok to export pme if there are no extraneous conductive parts in the out building ie gas/water pipes or structural steel framework

 

[Guest123]

Hi.

A PME system can be exported provided that the either of the following 2 conditions are met

1. There are no extraneous conductive parts within the outbuilding i.e steel frame, water service, gas service etc.

2. If there are conductive parts, then the equipotential zone needs to be extended to the outbuilding via main equipotential bonding conductors sized accordingly i.e a minimum of 10mm2 for each service back to the MET within the house, unless the sub-main is greater than 10mm2 itself.


Personally if there are conductive parts within the outbuilding then I always TT regardless of sub-main size.

 

[Wotsit]

Asked the dno about exporting pme a while ago, they said that they would rather pme was exported than not as this makes a much safer system. This was also elecsa's view.

 

[kung]

Yep my garage is steel frame with concrete blocks attached even if wooden id still tt regardless as someone could put in metal supports etc in futcher without any electrical knowledge and rodents could chew through cpc then no earth ! as it leves house and rats can chew through metal/concrete basically anything ! tt is and always will be safest bar none regardless what dno say.
Regards
Kung.

 

[flukey]

Yep my garage is steel frame with concrete blocks attached !

thought we were discussing the op`s shed

 

[kung]

thought we were discussing the op`s shed

So how do u know theres no metal frame installed ?

 

[flukey]

So how do u know theres no metal frame installed ?

how do you know there is

my reply covers all angles, yours says pme cant be exported

 

[kung]

how do you know there is

my reply covers all angles, yours says pme cant be exported

There lies the answer in the question nobody knows exept the op ! i wouldnt export tncs also this depends on the run.
plus tt = cheaper/better as i said what happens if the dno lose a neutral ?

 

[flukey]

There lies the answer in the question nobody knows exept the op ! i wouldnt export tncs also this depends on the run.

personal prefernce answer again then

i would export pme if no extraneous parts as its a far better system

 

[kung]

personal prefernce answer again then

i would export pme if no extraneous parts as its a far better system

Yep my mistake shouldnt have said its a no no ! its exeptable in some circumstances !
Regards
Kung.