Outside Electrics?

[Jbgood]

Hi i just after advice please

I'm thinking about adding electrics outside to the Shed, garage and decking area. Now i'm going to get a proper sparky in to relate with Part P.

Now the CU is at the front door, so will need to come from that to the outside. I have 2 spare blocks in the Cu left.

*Run 6.0mm T/E cable from the CU to the outside shed.
*From there install a RCD CU - which whould you say would be the best, i really want the garage and shed on seperate runs.
* Install 3 double sockets and 1 strip light in the shed.
* then the run from the shed to the garage is about 10m or so, what cable size should i use here? Swa?
* install 2 double sockets and 1 strip light in garage.
* From garage (deck on the side wall) install 3 outside lights, 1 outside switch, also i would like to switch the lights from the outside. (powered inside from garage).

I think that's in, now the shed will run a freezer and a tumble dryer, and as the freezer will be on all the time i want a system that if there is a problem with the garage electrice when i'm away it will only trip the garage electrics. So the freezer wont switch off, also if for the same reason the shed i want that not to interfere with the house electrics, as we have timed lights , freezer, alarm etc.

Now is there a way i can do this, because if somethings trips in our house our whole power goes off, i really dont want this happing.

Thanks for any help offered, i just want the information at hand so know how to tell the sparky aswell as knowing it myself.

 

[Steve]

Do you know if your freezer will work in temperatures below 10 degrees? Some wont.

That aside, you seem to have the right idea.

Use a 40A MCB at the house, no RCD yet.

Use a 5 or 6 way CU at the shed, with a 40 or 63A incomer
Run the following circuits from that

1. shed sockets - 30mA RCBO 20A radial in 4mm² cable (if you can get such a combined RCBO!)

2. outlet for freezer - 16A radial, no RCD, 2.5mm² cable. If its a large freezer, consider a Type C breaker, but your earth impedance must be low anough for this. The actual connection for the freezer shouldn't be a 3-pin plug, it should be either permenantly wired using an FCU or use a 15A round-pin socket and plug. This way, you cant plug any outdoor equipment into a non-RCD outlet.

3. radial for garage sockets - 32A MCB in shed CU, and run 6mm² SWA to garage, then use a small enclosure for an RCD and run a standard 32A ring in the garage, using FCU spurs for lights and outside lights etc in garage.

4. shed lights - 6A MCB, 1.0mm²

Thats how i'd do it, so the freezer is not protected by any RCDs. I'm sure others will do it differently.

Have you thought about exporting the house earth? This will affect the RCD arrangements - If you install a local earth rod (which needs testing etc) you need everything on an RCD (which can be the incomer on the shed CU and a time-delay type, reducing nuisance trips). If you import a TNCS or PME earth, you can do it as I have described, but some sparks have issues with exporting PME earths, as they can be different to true earth, thus having a potential between the shed wiring earth and the real earth.

And Part P - what exactly do you mean by "relate with part p"? many sparks wont sign off other people's work (and legally they shouldn't). Get the spark involved first, before you start anything. Or use LABC to sign off the work.

Long post!!! Phew!

 

[ban-all-sheds]

*Run 6.0mm T/E cable from the CU to the outside shed.

No - SWA.

*From there install a RCD CU - which whould you say would be the best, i really want the garage and shed on seperate runs.

2 runs of SWA, then.

Now is there a way i can do this, because if somethings trips in our house our whole power goes off,

Then when this happens you'll lose the supplies to the shed and garage....

i really dont want this happing.

Then you either need to replace your house CU, or supply the outbuildings via switchfuses straight from the meter tails.

Thanks for any help offered, i just want the information at hand so know how to tell the sparky aswell as knowing it myself.

You need to tell him what you want to achieve, not how to do it...

 

[Jbgood]

Why would i need to get SWA instead of 6.0mm as this will be in the house, only asking as the price is far much more?

Also what CU would you recommend i ask for in the shed?

And when i say the shed and garage on seperate runs i mean from the CU in the shed.

 

[Jbgood]

Thanks Crafty, just read your post in full, very helpful.