Earthing for Shed - disconnect house earth?

[ban-all-sheds]

OH, and the MCB that feeds the socket is rated at 20A, which I feel ought to be 32A if it has a ring main in the house.

Maybe it's not a ring - had you thought about that?

If it's not then there was absolutely nothing wrong with a branch running to the shed.

You were making design decisions without even finding out the type of circuit you were going to use to supply the shed?

If there is a spare space fora new MCB, would rather run new radial dedicated for the shed,

And how would you test that?

Come to that, how will you test any of the work you plan to do? Do you know what tests to do - what sequence to do them in and at what point you would energise the circuit(s), and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?

but still need to know whether to terminate the earth at the outside of building and use rod for shed, or continue house earth to the shed?

That was answered 10 minutes after your original post.

Not only are you woefully underestimating the amount of things you need to learn you can't even be bothered to read the answer to the 1 single question you thought was all you needed.

 

[Rusty2]

Thanks - guess what this means is back to calling in the guys who did it in the first place and getting them to check everything over!

By the way, although accept all you say about needing to know more - re CU issue - at the time I was considering this, I thought the feed was a dedicated radial with the socket on route - not a spur form another ringmain, so hopefully not quite as daft as may have appeared, but accept still not proficient!

Thanks for advice and support!

 

[Robbie2]

Hi guys - I have been following discussion and now have concerns over my own shed set-up, which I thought was all pucker!

When I moved in the place had been extended and the house rewired - about 3 years ago.

I thought the outside electrics all looked really well done but having read the discussion am wondering if I should ahve it checked- this is because:
1. I have 2 sheds, with one feeding off the other, the set up is as follows;

House CU - radial to outside wall - external socket used outside to give power for garden but also to connect SWA for sehd 1

This then goes to shed 1 and ends in a small CU with an RCD trip, a 6amp and 16amp MCB for that shed.

On thew outsdie of the shed there is a weatehrproof junction box with splits the SWA so it can go to the other shed, and this is set up in side like the other.

As far as aware this was all done by professionals - have looked at the earthing and it seems that the wire protecting the SWA have been connected to house earth at outside socket, but not to the CU's in sheds. The earhts for both sheds are connected via 3rd cable in the SWA and the second shed has an earth cable running to a rod by it's side.

As say, it all looked pucker to me, but would you agree or should I get this looked at.

Thanks for any help you can provide!

 

[Robbie2]

Just noticed, Rusty2 is also in Suffolk - could the same people have worked on both properties?? I wonder.......

 

[ban-all-sheds]

Hi guys - I have been following discussion and now have concerns over my own shed set-up, which I thought was all pucker!

Pucker:

Pukka:

http://www.thefreedictionary.com/pukka

 

[ban-all-sheds]

at the time I was considering this, I thought the feed was a dedicated radial with the socket on route - not a spur form another ringmain

Err - if you thought it was a radial why did you think it wasn't right when you found it was on a 20A MCB, and felt it ought to be 32A?

 

[ban-all-sheds]

House CU - radial to outside wall - external socket used outside to give power for garden but also to connect SWA for sehd 1

Is the earth core of the SWA connected to anything in that socket? Or is it 2 core cable?

This then goes to shed 1 and ends in a small CU with an RCD trip, a 6amp and 16amp MCB for that shed.

Is it a plastic CU?

And it gets its earth via one core of the SWA running to Shed #2?

On thew outsdie of the shed there is a weatehrproof junction box with splits the SWA so it can go to the other shed, and this is set up in side like the other.

Is the armour connectivity maintained?

As far as aware this was all done by professionals - have looked at the earthing and it seems that the wire protecting the SWA have been connected to house earth at outside socket, but not to the CU's in sheds.

Be aware that there could be a potential difference between the earth in the sheds and the SWA gland in the external JB.

The earhts for both sheds are connected via 3rd cable in the SWA and the second shed has an earth cable running to a rod by it's side.

What size(s) are those cables?

As say, it all looked pucker to me, but would you agree or should I get this looked at.

Do you have any Electrical Installation Certificates?

Is your supply TN-C-S, TN-S or TT?

Are there any extraneous-conductive-parts in either shed?

 

[Robbie2]

Thank you ban-all-sheds for your help, these are the answers, I think:

3 core SWA - not connected to the house earth, just sheds and rod. It has been left unconnected at the external socket where it starts.

Cu s in both sheds are plastic -MK ones

Yes, the earth wire in SWA is joined between the 2 sheds and that then leads from shed 2 to the rod via what looks like 10mm earth cable

Armour - yes, all joints are connecting the armour together, which is also connected at the house end via the external socket

I'm no expert but the SWA looks as if the cables are slightly larger than normal 2.5mm ringmain cables inside, so guessing they are 3.0mm - could this be right?

Certificates - I have one for the extension and re-wiring work done, but neither one specifically mentions the shed, although I must admit there are a lot of figures which are above my understanding, so perhaps it does mention it in a way I don't undersdtand!

Thank you again for help - I am just concerned as to whether I have a safe set up or need to stop using it.

 

[Robbie2]

Just read the articles you gave links for - thank you again - the house part of earthing I will have to check out tonight and get back to you, but know the sheds have the earth rod which seems to be calle TT (is that right?)

I have read other article and don't think there are any extraneous conductors in either shed - just a few hand tools and garden equipment and chairs, no pipes or the such or the larger electrical equipment or heating (I should be so lucky).

Thanks.

 

[ban-all-sheds]

I'm no expert but the SWA looks as if the cables are slightly larger than normal 2.5mm ringmain cables inside, so guessing they are 3.0mm - could this be right?

No - next size up from 2.5mm² is 4mm².

But I wasn't thinking earlier - the supply size for the sheds is the size of the SWA, so using a core for the main earth conductor will be OK. If the size of the cable from the house is the same as the one between the sheds.