Do you need an earth rod for an outbuilding?

[Josh95]

Do i need an earth rod if i am running a supply to a shed/outbuilding ?

The incoming supply to the house is tnc-s

 

[Rpa07]

All due respect josh, this is one if not the most talked about subject and the answer is definitely in previous posts. All good information. Search the forum with the search button and then use the similar threads underneath the page as you scroll down.
See you in a couple of weeks! (that's how many there are)
You will find the answer but people will also pipe up. Cheers, Rob

 

[The Ghost]

Search for Exporting PME on this forum and it gives you the various alternatives for supply to garage. TT system is one option and to me makes the most sense but there are other ways.

 

[Pat H]

Of course the top hit if you search "Exporting PME" will be this Topic

 

[Last plumber]

Read the ' garage earth ' thread, that's still ongoing kind of !
If you spoke to 50 sparks, 25 will tell you one thing and the other 25 will tell you the another.
Then they'll argue amongst themselves a while whilst you have a brew.

 

[Taylortwocities]

Josh, there is an excellent article, that was published in the IET's Wiring Matters magazine that covers this, and other, issues relating to outbuildings power.
electrical installations outdoors: a supply to a detached outbuilding

Note; it was written a few years ago (16th edition) but the principles are the same.

 

[bigspark17]

So much more info required josh!

 

[Pat H]

Don't forget Josh there often isn't a right answer. The regulations often don't prescribe exact methods. They detail what you must do and what you mustn't do. But it also states that you can use alternative solutions as long as they provide equivalent or better safety to the suggested solutions.
As long as you aren't breaching a regulation (or doing so without a supported method to demonstrate your approach is safer, better etc) then the finer detail is just about choice and preference.
The best you can do is gather all the views. Check the regs yourself and come to your own solution. It won't be the solution everyone would chose but as long as its compliant and safe you are ok.

 

[tony mc]

Exporting Pme - http://www.electriciansforums.co.uk/threads/exporting-pme.113254/

 

[Josh95]

seems like a bit of a grey area.

 

[The Ghost]

Well essentially normally DNO's dont like extending PME to garages, outhouses. That is why A TT system is used. For instance if you asked your DNO would they guarantee their PME in your garage at say 20m away see what they say. Might be a good starting point for how you are gonna go about it?

 

[Pat H]

But surely some large houses will have runs greater than 20 mtrs? I know of some houses fed from one single phase supply with very long runs internally.
And for a garage using heavy SWA with its earth (larger than T&E CPC) surely you'd have as good if not better than a large house would have.

 

[bigspark17]

Read the ' garage earth ' thread, that's still ongoing kind of !
If you spoke to 50 sparks, 25 will tell you one thing and the other 25 will tell you the another.
Then they'll argue amongst themselves a while whilst you have a brew.

And maybe 5 would understand why their doing it which way!

 

[bigspark17]

seems like a bit of a grey area.

Not really a grey area atall, why dont you give us more info and tell us how you intend to do it and youll may get more advice.

 

[westward10]

And the band played on.

 

[Josh95]

Fed from a spur on an existing ring in the house with a 2.5mm 3 core swa running to the shed (about 10m away from the house). Im going to put a small consumer unit inside the shed with an rcd in with a 6a mcb for a few light & a 16a mcb to feed 2 double sockets.

The house is tnc-s.

Josh

 

[westward10]

So you will have a 16A for the sockets and a 13A at the FCU.

 

[Josh95]

Fed from a spur on an existing ring in the house with a 2.5mm 3 core swa running to the shed (about 10m away from the house). Im going to put a small consumer unit inside the shed with an rcd in with a 6a mcb for a few light & a 16a mcb to feed 2 double sockets.

The house is tnc-s.

Josh

 

[Josh95]

Fed from a spur on an existing ring inside the house with a 2.5mm 3core swa running to the shed (10m from the house). A small garage consumer unit in the shed with an rcd, a 6a mcb for 3 lights & a 16a mcb to feed 2 double sockets.

The house is tnc-s

Josh

 

[Josh95]

Fed from a spur on an existing ring inside the house with a 2.5mm 3core swa running to the shed (10m from the house). A small garage consumer unit in the shed with an rcd, a 6a mcb for 3 lights & a 16a mcb to feed 2 double sockets.

The house is tnc-s

Josh

 

[Josh95]

10A for the sockets then!

 

[Wilko]

Hi Josh, I'm thinking this design may be affected by reg 434.2 and 434.2.1(i) which seems to limit length of an un-fused spur to 3m.
I would add a new radial to CU. Cheers.

 

[Josh95]

Its not un-fused.

 

[Taylortwocities]

Fed from a spur on an existing ring inside the house

So there's a a 13A FCU from the ring final that the SWA connects to?

 

[westward10]

So it seems, probably doesn't need a CU just fit socket/s straight to it with a FCU for the lights.

 

[bigspark17]

Are there any extranneous conductive parts in the shed.? What type of shed isit?

 

[Taylortwocities]

That depends on if the circuit in the house is RCD protected. If not then a mini 'garage' CU may be preferable. But we do not know enough to guess. As posted several days ago.....:

So much more info required josh!

 

[Josh95]

Its not rcd protected in the house thats the reason for the cu in the shed.
No extraneous conductive parts & the shed is made of wood.

 

[Pat H]

If the ring in the house isn't RCD protected then I'd make the FCU an RCD unit so that the SWA is RCD protected as so is the shed.

TFP10WL TIMEGUARD, CONNECTION UNIT, RCD, FUSED, WHITE | Farnell element14 - http://uk.farnell.com/timeguard/tfp10wl/connection-unit-rcd-fused-white/dp/1642925?

A small CU in the summer house with a 10A for the sockets and a 6A for lights would then be ok.

That then opens the question of: Should the shed CU be metal...?

If remote from the house and not part of the habitation then possibly no but as its wood its flammable.

 

[Josh95]

Would an earth rod be needed ?

 

[Taylortwocities]

So there's a a 13A FCU from the ring final that the SWA connects to?

 

[Josh95]

Yes thats correct.

 

[Taylortwocities]

Ok, I would put garage RCD protected CU in shed. 16A radial for sockets. 6A for lights.
Export earth from house.

 

[Last plumber]

And maybe 5 would understand why their doing it which way!

Yes big spark. You're 100% right.
The trouble is, all electricians give a very convincing argument for either method.
So it's finding out which half of the discussion, those 5 belong to.
Especially when this is this first time I have had to think through this particular issue.
I wasn't trying to insult anyone.

 

[westward10]

Ok, I would put garage RCD protected CU in shed. 16A radial for sockets. 6A for lights.
Export earth from house.

10A on skts as the FCU will have max 13A fuse.

 

[ETO]

Have you put a low price in then realised to do it proper will be more expensive?

 

[happy chap]

Its not rcd protected in the house thats the reason for the cu in the shed.
No extraneous conductive parts & the shed is made of wood.

 

[happy chap]

Josh Josh Josh i have looked at your thread and have joined to reply to how unhelpful and belittling the support some people give. but others are there to help.

 

[Trevor g]

I'm not sure .I've always put Rod in but saw an article and it said it could create problems

 

[DPG]

I'm not sure .I've always put Rod in but saw an article and it said it could create problems

Welcome to the forum! Worth bearing in mind this thread is around 7 years old though.