Shed Supply

[RED_B]

Evening all.
I'll start by apologise for asking what is probably a common question for you guys here.

I work in electronics so bare with me.

I would like power in my shed; just going to be ring circuit in there, a couple of strip lights and a couple of outside lights too.
I plan on doing as much of it as I can myself. It's about 30m run from my fuse board. After asking a few sparks I know they said I would need a 6mm 2 core cable that would then go into an adaptable box and join on with a 6mm twin and earth cable into my metal 2 way consumer unit. Along with a 10mm earth from an earth rod.

Basically what I am not sure about is, instead of running 30m of SWA, can I run a 6mm Twin and earth from my fuse board, through the house and then join on to an SWA in the same way as at the shed end? The earth in the twin and earth joining on to a banjo so I can still have a 2 core on the outside part?

Next thing I wasn't sure about is; my fuse board was recently changed but obviously need a seperate breaker for the shed but apparently it is best to not have it on RCD? Can it just go straight next to the main switch and not on RCD?

Thanks and sorry my post drags on.

 

[RED_B]

Oh and would a 32Amp breaker be okay?

 

[Wilko]

Hi Red, welcome to the forum.
The design of shed electrics is simple enough but it still needs to be got right in detail. A few thoughts : SWA can be joined to the twin and earth, 32A is plenty for a shed, bonding may not be required (if there is no gas or water in the shed) and you need to understand your house earthing arrangements and decide whether you treat the shed as TNS or TT. Here is a link to an IET info doc on shed supply for your night time reading. There will be a test
http://electrical.------.org/wiring-matters/16/elect-inst-outdoors.cfm?type=pdf

 

[RED_B]

Thanks for the reply Wilko.

There is no gas or water in the shed and the earthing for the house is a PME..(I remember the spark who changed my fuse board over attempting to explain what that is to me)

 

[DPG]

I'd be interested to know why these sparks all said to use an earth rod. Also, it doesn't seem like you have the knowledge to be able to design this safely. No offence intended at all, but best to be safe. Maybe whoever you get in to do the job will let you route the armoured cable to save a little bit? Daz

 

[RED_B]

I'd be interested to know why these sparks all said to use an earth rod. Also, it doesn't seem like you have the knowledge to be able to design this safely. No offence intended at all, but best to be safe. Maybe whoever you get in to do the job will let you route the armoured cable to save a little bit? Daz

To keep it from tripping anything in the house if there is a problem in there from what I can gather.
I'm not sure how I've said anything that is unsafe? I've relayed a few bits I have been told and asking a couple of extra questions on how to go about things and Wilko so far has been of help.

If any of what I have said is unsafe then please let me know. It's something I would like to do myself and feel I can do it well once I am confident that the way I have said about doing it is a good way of doing it. I will be having an electrician test it all for me at the end of it.

 

[westward10]

Oh and would a 32Amp breaker be okay?

Only thing with 32A at source is that you won't want a 32A ring final in shed as you lose discrimination between devices. Probably only need a 20A radial for the sockets.

 

[Midwest]

OP, as this will be a new circuit, you will need to notify the local building control. If you electrician is in a government approved scheme, he/she can do this for you. If not, you will have to get prior approval from your lbc. For you electrician to do 3rd party testing, he will almost probably have to be registered with Stroma, as I think they are the only current scheme that approve 3rd party testing.

I understand the enthusiasm to do some diy work yourself, and save some money, but carrying out electrical work requires training, knowledge, expertise and the correct tools. Most dyers do not possess all those attributes.

 

[bigspark17]

What material is the shed? Wood or metal.?

 

[DPG]

To keep it from tripping anything in the house if there is a problem in there from what I can gather.
I'm not sure how I've said anything that is unsafe? I've relayed a few bits I have been told and asking a couple of extra questions on how to go about things and Wilko so far has been of help.

If any of what I have said is unsafe then please let me know. It's something I would like to do myself and feel I can do it well once I am confident that the way I have said about doing it is a good way of doing it. I will be having an electrician test it all for me at the end of it.

Mmm. I was meaning why use a rod to provide the earth rather than using the system earth. Unless any bonding is needed maybe? Daz

 

[sparksburnout]

Simple statement/question. You have stated that you are coming off your fuse-board, so, presumably a NEW circuit. To keep on the right side of the law, this needs notifying to your local building control. Have you asked how much this will cost? I think it is about £350 round here, maybe a bit less. A registered electrician can do this for you, and may not charge much more for the whole job. Therefore, is there much point going on? Just get one of these guys you have been asking to do the job, properly.

 

[Leesparkykent]

Only thing with 32A at source is that you won't want a 32A ring final in shed as you lose discrimination between devices. Probably only need a 20A radial for the sockets.

Even a 20A wouldn't achieve discrimination. Its a bad design to install a distribution circuit having a 60898 supplying it and final circuits the other end on 60898s. Practically in a domestic situation its near on impossible to achieve discrimination with mcbs in series. IIRC for full discrimination the distribution circuit MCB would have to be in the region of 125A to fully discriminate with a 20A or 32A MCB. Although discrimination might not really be an issue unless they are going to have a fridge freezer or similar in the shed.

 

[westward10]

Even a 20A wouldn't achieve discrimination. Its a bad design to install a distribution circuit having a 60898 supplying it and final circuits the other end on 60898s. Practically in a domestic situation its near on impossible to achieve discrimination with mcbs in series. IIRC for full discrimination the distribution circuit MCB would have to be in the region of 125A to fully discriminate with a 20A or 32A MCB. Although discrimination might not really be an issue unless they are going to have a fridge freezer or similar in the shed.

I agree with fault protection but for overcurrent is what I was really getting at.

 

[Midwest]

Simple statement/question. You have stated that you are coming off your fuse-board, so, presumably a NEW circuit. To keep on the right side of the law, this needs notifying to your local building control. Have you asked how much this will cost? I think it is about £350 round here, maybe a bit less. A registered electrician can do this for you, and may not charge much more for the whole job. Therefore, is there much point going on? Just get one of these guys you have been asking to do the job, properly.

There's a terrible echo in here.

 

[westward10]

There's a terrible echo in here.

Say again